Trial Outcomes & Findings for Heart Rate Variability and Emotion Regulation (NCT NCT03458910)

NCT ID: NCT03458910

Last Updated: 2025-07-23

Results Overview

The strength of resting-state functional connectivity was measured by correlation coefficients. Values represent the correlation of BOLD time-series between mPFC and the right amygdala. Higher values indicate greater connectivity.

• Recruitment status: TERMINATED
• Study phase: NA
• Target enrollment: 193 participants
• Primary outcome timeframe: Time 1 (Baseline), Time 2 (5 weeks)
• Results posted on: 2025-07-23

Participant Flow

Participant milestones

Measure	Younger HRV-increase Group Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.	Older HRV-increase Group Participants in this group were between the ages of 55 and 80. Half of the older participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Older HRV-decrease Group Participants in this group were between the ages of 55 and 80. Half of the older participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Overall Study STARTED	63	58	37	35
Overall Study COMPLETED	56	50	28	28
Overall Study NOT COMPLETED	7	8	9	7

Reasons for withdrawal

Measure	Younger HRV-increase Group Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.	Older HRV-increase Group Participants in this group were between the ages of 55 and 80. Half of the older participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Older HRV-decrease Group Participants in this group were between the ages of 55 and 80. Half of the older participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Overall Study Withdrawal by Subject	7	8	6	4
Overall Study Study halted due to risk of catching COVID-19	0	0	3	3

Baseline Characteristics

Heart Rate Variability and Emotion Regulation

Baseline characteristics by cohort

Measure	Younger HRV-increase Group n=63 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=58 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.	Older HRV-increase Group n=37 Participants Participants in this group were between the ages of 55 and 80. Half of the older participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Older HRV-decrease Group n=35 Participants Participants in this group were between the ages of 55 and 80. Half of the older participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.	Total n=193 Participants Total of all reporting groups
Age, Categorical <=18 years	6 Participants n=5 Participants	4 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants	10 Participants n=21 Participants
Age, Categorical Between 18 and 65 years	57 Participants n=5 Participants	54 Participants n=7 Participants	21 Participants n=5 Participants	14 Participants n=4 Participants	146 Participants n=21 Participants
Age, Categorical >=65 years	0 Participants n=5 Participants	0 Participants n=7 Participants	16 Participants n=5 Participants	21 Participants n=4 Participants	37 Participants n=21 Participants
Age, Continuous	22.71 years STANDARD_DEVIATION 2.47 • n=5 Participants	22.66 years STANDARD_DEVIATION 3.17 • n=7 Participants	65.03 years STANDARD_DEVIATION 8.29 • n=5 Participants	65.66 years STANDARD_DEVIATION 5.88 • n=4 Participants	38.68 years STANDARD_DEVIATION 21.28 • n=21 Participants
Sex: Female, Male Female	31 Participants n=5 Participants	29 Participants n=7 Participants	24 Participants n=5 Participants	21 Participants n=4 Participants	105 Participants n=21 Participants
Sex: Female, Male Male	32 Participants n=5 Participants	29 Participants n=7 Participants	13 Participants n=5 Participants	14 Participants n=4 Participants	88 Participants n=21 Participants
Ethnicity (NIH/OMB) Hispanic or Latino	2 Participants n=5 Participants	5 Participants n=7 Participants	2 Participants n=5 Participants	3 Participants n=4 Participants	12 Participants n=21 Participants
Ethnicity (NIH/OMB) Not Hispanic or Latino	55 Participants n=5 Participants	48 Participants n=7 Participants	35 Participants n=5 Participants	31 Participants n=4 Participants	169 Participants n=21 Participants
Ethnicity (NIH/OMB) Unknown or Not Reported	6 Participants n=5 Participants	5 Participants n=7 Participants	0 Participants n=5 Participants	1 Participants n=4 Participants	12 Participants n=21 Participants
Race (NIH/OMB) American Indian or Alaska Native	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants	0 Participants n=21 Participants
Race (NIH/OMB) Asian	43 Participants n=5 Participants	38 Participants n=7 Participants	5 Participants n=5 Participants	6 Participants n=4 Participants	92 Participants n=21 Participants
Race (NIH/OMB) Native Hawaiian or Other Pacific Islander	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants	0 Participants n=21 Participants
Race (NIH/OMB) Black or African American	4 Participants n=5 Participants	0 Participants n=7 Participants	12 Participants n=5 Participants	2 Participants n=4 Participants	18 Participants n=21 Participants
Race (NIH/OMB) White	9 Participants n=5 Participants	13 Participants n=7 Participants	18 Participants n=5 Participants	25 Participants n=4 Participants	65 Participants n=21 Participants
Race (NIH/OMB) More than one race	2 Participants n=5 Participants	2 Participants n=7 Participants	2 Participants n=5 Participants	1 Participants n=4 Participants	7 Participants n=21 Participants
Race (NIH/OMB) Unknown or Not Reported	5 Participants n=5 Participants	5 Participants n=7 Participants	0 Participants n=5 Participants	1 Participants n=4 Participants	11 Participants n=21 Participants
Region of Enrollment United States	63 Participants n=5 Participants	58 Participants n=7 Participants	37 Participants n=5 Participants	35 Participants n=4 Participants	193 Participants n=21 Participants

PRIMARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

The strength of resting-state functional connectivity was measured by correlation coefficients. Values represent the correlation of BOLD time-series between mPFC and the right amygdala. Higher values indicate greater connectivity.

Outcome measures

Measure	Younger HRV-increase Group n=49 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=47 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
mPFC-right Amygdala Resting-state Functional Connectivity for Younger Adults (ANOVA) Time 2	0.116 correlation coefficients Standard Error 0.015	0.090 correlation coefficients Standard Error 0.015
mPFC-right Amygdala Resting-state Functional Connectivity for Younger Adults (ANOVA) Time 1	0.104 correlation coefficients Standard Error 0.105	0.086 correlation coefficients Standard Error 0.015

PRIMARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

The strength of resting-state functional connectivity was measured by correlation coefficients. Values represent the correlation of BOLD time-series between mPFC and the right amygdala. Higher values indicate greater connectivity.

Outcome measures

Measure	Younger HRV-increase Group n=26 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=25 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
mPFC-right Amygdala Resting-state Functional Connectivity for Older Adults (ANOVA) Time 1	0.109 correlation coefficients Standard Error 0.045	0.140 correlation coefficients Standard Error 0.046
mPFC-right Amygdala Resting-state Functional Connectivity for Older Adults (ANOVA) Time 2	0.125 correlation coefficients Standard Error 0.046	0.095 correlation coefficients Standard Error 0.047

PRIMARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

The strength of resting-state functional connectivity between mPFC and the right amygdala was measured by correlation coefficients. The difference in functional connectivity between the two time points (Time 2 - Time 1) was calculated. Higher values indicate greater connectivity at Time 2 than Time 1 (or post- than pre-intervention).

Outcome measures

Measure	Younger HRV-increase Group n=49 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=47 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
mPFC-right Amygdala Resting-state Functional Connectivity for Younger Adults (Post-Pre)	0.011 correlation coefficients Standard Error 0.022	-0.016 correlation coefficients Standard Error 0.024

PRIMARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

The strength of resting-state functional connectivity between mPFC and the right amygdala was measured by correlation coefficients. The difference in functional connectivity between the two time points (Time 2 - Time 1) was calculated. Higher values indicate greater connectivity at Time 2 than Time 1 (or post- than pre-intervention).

Outcome measures

Measure	Younger HRV-increase Group n=26 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=25 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
mPFC-right Amygdala Resting-state Functional Connectivity for Older Adults (Post-Pre)	0.016 correlation coefficients Standard Error 0.072	-0.045 correlation coefficients Standard Error 0.046

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

Emotional intensity ratings, which participants reported during the emotion regulation task inside MRI scanner before and after intervention. The ratings ranged from 1 through 4, and 4 represents strongest intensity.

Outcome measures

Measure	Younger HRV-increase Group n=44 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=39 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Emotion Regulation in Younger Adults (Behavior) Time 1: down-regulation	1.841 score on a scale Standard Error 0.080	1.822 score on a scale Standard Error 0.085
Emotion Regulation in Younger Adults (Behavior) Time 1: viewing	2.073 score on a scale Standard Error 0.084	2.309 score on a scale Standard Error 0.089
Emotion Regulation in Younger Adults (Behavior) Time 1: up-regulation	3.141 score on a scale Standard Error 0.072	3.271 score on a scale Standard Error 0.076
Emotion Regulation in Younger Adults (Behavior) Time 2: down-regulation	1.861 score on a scale Standard Error 0.075	1.959 score on a scale Standard Error 0.080
Emotion Regulation in Younger Adults (Behavior) Time 2: viewing	1.964 score on a scale Standard Error 0.078	2.427 score on a scale Standard Error 0.083
Emotion Regulation in Younger Adults (Behavior) Time 2: up-regulation	3.269 score on a scale Standard Error 0.070	3.395 score on a scale Standard Error 0.074

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

Emotional intensity ratings, which participants reported during the emotion regulation task inside MRI scanner before and after intervention. The ratings ranged from 1 through 4, and 4 represents strongest intensity.

Outcome measures

Measure	Younger HRV-increase Group n=18 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=19 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Emotion Regulation in Older Adults (Behavior) Time 1: down-regulation	2.059 score on a scale Standard Error 0.085	1.973 score on a scale Standard Error 0.119
Emotion Regulation in Older Adults (Behavior) Time 1: viewing	2.586 score on a scale Standard Error 0.096	2.511 score on a scale Standard Error 0.134
Emotion Regulation in Older Adults (Behavior) Time 1: up-regulation	3.117 score on a scale Standard Error 0.087	3.022 score on a scale Standard Error 0.121
Emotion Regulation in Older Adults (Behavior) Time 2: down-regulation	2.115 score on a scale Standard Error 0.087	2.061 score on a scale Standard Error 0.122
Emotion Regulation in Older Adults (Behavior) Time 2: viewing	2.668 score on a scale Standard Error 0.116	2.695 score on a scale Standard Error 0.162
Emotion Regulation in Older Adults (Behavior) Time 2: up-regulation	3.279 score on a scale Standard Error 0.069	3.155 score on a scale Standard Error 0.097

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

We measured percent changes (%) in BOLD activity in the left amygdala region during emotion down-regulation, viewing, and up-regulation before and after intervention. The viewing condition was used as a baseline during the task. The change is represented by %.

Outcome measures

Measure	Younger HRV-increase Group n=45 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=39 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Left Amygdala BOLD Activity During Emotion Regulation in Younger Adults Time 1: down-regulation	0.032 Percent changes (%) in BOLD signal Standard Error 0.022	0.024 Percent changes (%) in BOLD signal Standard Error 0.023
Left Amygdala BOLD Activity During Emotion Regulation in Younger Adults Time 1: viewing	0.029 Percent changes (%) in BOLD signal Standard Error 0.023	0.048 Percent changes (%) in BOLD signal Standard Error 0.035
Left Amygdala BOLD Activity During Emotion Regulation in Younger Adults Time 1: up-regulation	0.107 Percent changes (%) in BOLD signal Standard Error 0.026	0.095 Percent changes (%) in BOLD signal Standard Error 0.028
Left Amygdala BOLD Activity During Emotion Regulation in Younger Adults Time 2: down-regulation	0.027 Percent changes (%) in BOLD signal Standard Error 0.021	0.021 Percent changes (%) in BOLD signal Standard Error 0.022
Left Amygdala BOLD Activity During Emotion Regulation in Younger Adults Time 2: viewing	0.018 Percent changes (%) in BOLD signal Standard Error 0.019	-0.020 Percent changes (%) in BOLD signal Standard Error 0.021
Left Amygdala BOLD Activity During Emotion Regulation in Younger Adults Time 2: up-regulation	0.121 Percent changes (%) in BOLD signal Standard Error 0.027	0.074 Percent changes (%) in BOLD signal Standard Error 0.029

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

We measured percent changes (%) in BOLD activity in the left amygdala region during emotion down-regulation, viewing, and up-regulation before and after intervention. The viewing condition was used as a baseline during the task. The change is represented by %.

Outcome measures

Measure	Younger HRV-increase Group n=21 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=20 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Left Amygdala BOLD Activity During Emotion Regulation in Older Adults Time 1: down-regulation	-0.069 Percent changes (%) in BOLD signal Standard Error 0.041	-0.028 Percent changes (%) in BOLD signal Standard Error 0.043
Left Amygdala BOLD Activity During Emotion Regulation in Older Adults Time 1: viewing	-0.092 Percent changes (%) in BOLD signal Standard Error 0.039	-0.006 Percent changes (%) in BOLD signal Standard Error 0.040
Left Amygdala BOLD Activity During Emotion Regulation in Older Adults Time 1: up-regulation	-0.043 Percent changes (%) in BOLD signal Standard Error 0.052	0.067 Percent changes (%) in BOLD signal Standard Error 0.053
Left Amygdala BOLD Activity During Emotion Regulation in Older Adults Time 2: down-regulation	-0.068 Percent changes (%) in BOLD signal Standard Error 0.037	-0.035 Percent changes (%) in BOLD signal Standard Error 0.038
Left Amygdala BOLD Activity During Emotion Regulation in Older Adults Time 2: viewing	-0.004 Percent changes (%) in BOLD signal Standard Error 0.030	-0.013 Percent changes (%) in BOLD signal Standard Error 0.031
Left Amygdala BOLD Activity During Emotion Regulation in Older Adults Time 2: up-regulation	-0.013 Percent changes (%) in BOLD signal Standard Error 0.031	0.036 Percent changes (%) in BOLD signal Standard Error 0.032

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

We measured percent changes (%) in BOLD activity in the right amygdala region during emotion down-regulation, viewing, and up-regulation before and after intervention. The viewing condition was used as a baseline during the task. The change is represented by %.

Outcome measures

Measure	Younger HRV-increase Group n=45 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=39 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Right Amygdala BOLD Activity During Emotion Regulation in Younger Adults Time 1: down-regulation	0.019 Percent changes (%) in BOLD signal Standard Error 0.021	0.018 Percent changes (%) in BOLD signal Standard Error 0.023
Right Amygdala BOLD Activity During Emotion Regulation in Younger Adults Time 1: viewing	0.032 Percent changes (%) in BOLD signal Standard Error 0.021	0.039 Percent changes (%) in BOLD signal Standard Error 0.022
Right Amygdala BOLD Activity During Emotion Regulation in Younger Adults Time 1: up-regulation	0.054 Percent changes (%) in BOLD signal Standard Error 0.024	0.074 Percent changes (%) in BOLD signal Standard Error 0.025
Right Amygdala BOLD Activity During Emotion Regulation in Younger Adults Time 2: down-regulation	0.076 Percent changes (%) in BOLD signal Standard Error 0.026	0.017 Percent changes (%) in BOLD signal Standard Error 0.028
Right Amygdala BOLD Activity During Emotion Regulation in Younger Adults Time 2: viewing	0.073 Percent changes (%) in BOLD signal Standard Error 0.027	-0.003 Percent changes (%) in BOLD signal Standard Error 0.029
Right Amygdala BOLD Activity During Emotion Regulation in Younger Adults Time 2: up-regulation	0.106 Percent changes (%) in BOLD signal Standard Error 0.025	0.068 Percent changes (%) in BOLD signal Standard Error 0.027

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

We measured percent changes (%) in BOLD activity in the right amygdala region during emotion down-regulation, viewing, and up-regulation before and after intervention. The viewing condition was used as a baseline during the task. The change is represented by %.

Outcome measures

Measure	Younger HRV-increase Group n=21 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=20 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Right Amygdala BOLD Activity During Emotion Regulation in Older Adults Time 1: viewing	0.005 Percent changes (%) in BOLD signal Standard Error 0.029	-0.027 Percent changes (%) in BOLD signal Standard Error 0.030
Right Amygdala BOLD Activity During Emotion Regulation in Older Adults Time 1: up-regulation	0.041 Percent changes (%) in BOLD signal Standard Error 0.045	0.062 Percent changes (%) in BOLD signal Standard Error 0.047
Right Amygdala BOLD Activity During Emotion Regulation in Older Adults Time 2: up-regulation	0.006 Percent changes (%) in BOLD signal Standard Error 0.038	0.024 Percent changes (%) in BOLD signal Standard Error 0.039
Right Amygdala BOLD Activity During Emotion Regulation in Older Adults Time 1: down-regulation	-0.058 Percent changes (%) in BOLD signal Standard Error 0.052	-0.014 Percent changes (%) in BOLD signal Standard Error 0.053
Right Amygdala BOLD Activity During Emotion Regulation in Older Adults Time 2: down-regulation	-0.038 Percent changes (%) in BOLD signal Standard Error 0.031	-0.004 Percent changes (%) in BOLD signal Standard Error 0.032
Right Amygdala BOLD Activity During Emotion Regulation in Older Adults Time 2: viewing	-0.005 Percent changes (%) in BOLD signal Standard Error 0.027	0.001 Percent changes (%) in BOLD signal Standard Error 0.027

SECONDARY outcome

Timeframe: one time point: at study completion, which is the end of 5-week training

Population: Population analyzed was composed by all randomization subjects who completed the decision making task, who were unfamiliar with the task and whose data quality was sufficient for data analysis.

The decision-making ability was measured by multiple-choice responses during a computer-based task.

Median percentage of acceptance of unfair offers and fair offers were calculated.

A higher percentage of accepted both unfair and fair offers points toward more rational decision-making and likely better emotion regulation.

This task was administered only at post-intervention (but not pre-intervention).

Outcome measures

Measure	Younger HRV-increase Group n=35 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=33 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Decision-making for Younger Adults at Post Intervention (Behavior) percentage of acceptance of fair offers	100 percentage of offers Interval 100.0 to 100.0	100 percentage of offers Interval 100.0 to 100.0
Decision-making for Younger Adults at Post Intervention (Behavior) percentage of acceptance of unfair offers	33.33 percentage of offers Interval 5.56 to 72.22	33.33 percentage of offers Interval 5.72 to 80.21

SECONDARY outcome

Timeframe: one time point: at study completion, which is the end of 5-week training

Population: Population analyzed was composed by all randomization subjects who completed the decision making task, whose data quality was sufficient for data analysis and who were unfamiliar with the task.

We measured percent changes (%) in BOLD activity in the dorsal anterior cingulate cortex and anterior insula during a computer-based decision-making task. Higher values indicate greater activity.

Outcome measures

Measure	Younger HRV-increase Group n=31 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=30 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Decision-making for Younger Adults (fMRI) Anterior insula activation	0.0740 Percent changes (%) in BOLD signal Standard Error 0.0214	0.0135 Percent changes (%) in BOLD signal Standard Error 0.0229
Decision-making for Younger Adults (fMRI) Dorsal anterior cingulate cortex activation	0.1073 Percent changes (%) in BOLD signal Standard Error 0.0221	0.0177 Percent changes (%) in BOLD signal Standard Error 0.0278

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

Emotional well-being measured by the Profile of Mood States (POMS) for younger adults.

The POMS consists of 40 items that are rated on a 5-point scale ranging from "0=not at all" to "4=extremely. Total Mood Disturbance (TMD) was calculated by summing the totals for the negative items and then subtracting the totals for the positive items. A constant (i.e., 100) was added to the TMD formula in order to eliminate negative scores. Higher scores indicate more negative mood states. The scores range from 56 and 216.

Outcome measures

Measure	Younger HRV-increase Group n=53 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=50 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Mood for Younger Adults Time 1	92.604 score on a scale Standard Deviation 14.270	93.560 score on a scale Standard Deviation 18.307
Mood for Younger Adults Time 2	89.726 score on a scale Standard Deviation 18.710	86.540 score on a scale Standard Deviation 18.967

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

Emotional well-being measured by the Profile of Mood States (POMS) for older adults.

The POMS consists of 40 items that are rated on a 5-point scale ranging from "0=not at all" to "4=extremely. Total Mood Disturbance (TMD) was calculated by summing the totals for the negative items and then subtracting the totals for the positive items. A constant (i.e., 100) was added to the TMD formula in order to eliminate negative scores. Higher scores indicate more negative mood states. The scores range from 56 and 216.

Outcome measures

Measure	Younger HRV-increase Group n=27 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=28 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Mood for Older Adults Time 1	87.167 score on a scale Standard Deviation 17.435	90.250 score on a scale Standard Deviation 17.037
Mood for Older Adults Time 2	79.852 score on a scale Standard Deviation 12.440	87.536 score on a scale Standard Deviation 18.339

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

Emotional well-being measured by the Center for Epidemiological Studies Depression Scale (CES-D) for younger adults.

The CES-D consists of 20 items that are rated on a scale of 0 to 3 (0 = Rarely or None of the Time, 1 = Some or Little of the Time, 2 = Moderately or Much of the time, 3 = Most or Almost All the Time). Possible range of scores is 0 to 60, with the higher scores indicating more depressive symptoms.

Outcome measures

Measure	Younger HRV-increase Group n=55 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=49 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Depression for Younger Adults Time 1	16.164 score on a scale Standard Deviation 8.046	14.571 score on a scale Standard Deviation 9.372
Depression for Younger Adults Time 2	13.218 score on a scale Standard Deviation 8.774	11.837 score on a scale Standard Deviation 8.880

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Emotional well-being measured by the Center for Epidemiological Studies Depression Scale (CES-D) for older adults.

The CES-D consists of 20 items that are rated on a scale of 0 to 3 (0 = Rarely or None of the Time, 1 = Some or Little of the Time, 2 = Moderately or Much of the time, 3 = Most or Almost All the Time). Possible range of scores is 0 to 60, with the higher scores indicating more depressive symptoms.

Outcome measures

Measure	Younger HRV-increase Group n=27 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=28 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Depression for Older Adults Time 1	8.852 score on a scale Standard Deviation 7.383	14.143 score on a scale Standard Deviation 9.816
Depression for Older Adults Time 2	6.481 score on a scale Standard Deviation 4.839	11.964 score on a scale Standard Deviation 8.963

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

Emotional well-being measured by the State Anxiety Inventory (SAI) for younger adults.

The SAI consists of 20 items that are rated on a 4-point scale as follows: 1) not at all, 2) somewhat, 3) moderately so, and 4) very much so. Scores range from 20 to 80, with higher scores indicating greater state anxiety.

Outcome measures

Measure	Younger HRV-increase Group n=53 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=49 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
State Anxiety for Younger Adults Time 1	38.566 score on a scale Standard Deviation 10.233	38.122 score on a scale Standard Deviation 11.245
State Anxiety for Younger Adults Time 2	37.972 score on a scale Standard Deviation 10.511	36.347 score on a scale Standard Deviation 11.816

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

Emotional well-being measured by the State Anxiety Inventory (SAI) for older adults.

The SAI consists of 20 items that are rated on a 4-point scale as follows: 1) not at all, 2) somewhat, 3) moderately so, and 4) very much so. Scores range from 20 to 80, with higher scores indicating greater state anxiety.

Outcome measures

Measure	Younger HRV-increase Group n=28 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=27 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
State Anxiety for Older Adults Time 1	31.786 score on a scale Standard Deviation 8.741	33.889 score on a scale Standard Deviation 11.078
State Anxiety for Older Adults Time 2	30.143 score on a scale Standard Deviation 7.966	33.963 score on a scale Standard Deviation 10.082

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

Emotional well-being measured by the Trait Anxiety Inventory (TAI) for younger adults.

The TAI consists of 20 items that are rated on a 4-point scale as follows: 1) not at all, 2) somewhat, 3) moderately so, and 4) very much so. Scores range from 20 to 80, with higher scores indicating greater trait anxiety.

Outcome measures

Measure	Younger HRV-increase Group n=55 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=49 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Trait Anxiety for Younger Adults Time 1	42.473 score on a scale Standard Deviation 9.933	41.306 score on a scale Standard Deviation 12.582
Trait Anxiety for Younger Adults Time 2	38.909 score on a scale Standard Deviation 9.487	38.510 score on a scale Standard Deviation 10.679

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

Emotional well-being measured by the Trait Anxiety Inventory (TAI) for older adults.

The TAI consists of 20 items that are rated on a 4-point scale as follows: 1) not at all, 2) somewhat, 3) moderately so, and 4) very much so. Scores range from 20 to 80, with higher scores indicating greater trait anxiety.

Outcome measures

Measure	Younger HRV-increase Group n=28 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=27 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Trait Anxiety for Older Adults Time 1	33.821 score on a scale Standard Deviation 11.039	38.815 score on a scale Standard Deviation 12.830
Trait Anxiety for Older Adults Time 2	31.929 score on a scale Standard Deviation 9.071	36.093 score on a scale Standard Deviation 10.517

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

Difference in stress recovery elicited by standard cognitive tasks, as assessed by change in systolic blood pressure from cognitive tasks to recovery rest

Outcome measures

Measure	Younger HRV-increase Group n=50 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=45 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Stress Recovery (Systolic Blood Pressure) for Younger Adults Time 1	-2.993 mmHg Standard Deviation 8.176	-3.253 mmHg Standard Deviation 6.465
Stress Recovery (Systolic Blood Pressure) for Younger Adults Time 2	-1.973 mmHg Standard Deviation 6.728	-0.702 mmHg Standard Deviation 10.165

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

Difference in stress recovery elicited by standard cognitive tasks, as assessed by change in systolic blood pressure from cognitive tasks to recovery rest

Outcome measures

Measure	Younger HRV-increase Group n=23 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=22 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Stress Recovery (Systolic Blood Pressure) for Older Adults Time 1	-6.464 mmHg Standard Deviation 19.150	-6.650 mmHg Standard Deviation 6.060
Stress Recovery (Systolic Blood Pressure) for Older Adults Time 2	-4.592 mmHg Standard Deviation 17.651	-4.380 mmHg Standard Deviation 7.402

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

Difference in stress recovery elicited by standard cognitive tasks, as assessed by change in heart rate from cognitive tasks to recovery rest

Outcome measures

Measure	Younger HRV-increase Group n=31 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=30 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Stress Recovery (Heart Rate) for Younger Adults Time 1	-3.851 beats per minute Standard Deviation 6.585	-1.870 beats per minute Standard Deviation 4.133
Stress Recovery (Heart Rate) for Younger Adults Time 2	-2.302 beats per minute Standard Deviation 4.658	-1.486 beats per minute Standard Deviation 3.734

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

Difference in stress recovery elicited by standard cognitive tasks, as assessed by change in heart rate from cognitive tasks to recovery rest

Outcome measures

Measure	Younger HRV-increase Group n=13 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=16 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Stress Recovery (Heart Rate) for Older Adults Time 1	-3.921 beats per minute Standard Deviation 4.760	-2.188 beats per minute Standard Deviation 2.111
Stress Recovery (Heart Rate) for Older Adults Time 2	-2.716 beats per minute Standard Deviation 2.921	-1.267 beats per minute Standard Deviation 2.894

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

Difference in stress recovery elicited by standard cognitive tasks, as assessed by change in breathing rate from cognitive tasks to recovery rest

Outcome measures

Measure	Younger HRV-increase Group n=46 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=40 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Stress Recovery (Breathing Rate) for Younger Adults Time 1	-3.555 breaths per minute Standard Deviation 3.121	-4.134 breaths per minute Standard Deviation 3.097
Stress Recovery (Breathing Rate) for Younger Adults Time 2	-4.722 breaths per minute Standard Deviation 4.070	-1.563 breaths per minute Standard Deviation 2.533

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

Difference in stress recovery elicited by standard cognitive tasks, as assessed by change in breathing rate from cognitive tasks to recovery rest

Outcome measures

Measure	Younger HRV-increase Group n=18 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=18 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Stress Recovery (Breathing Rate) for Older Adults Time 1	-3.935 breaths per minute Standard Deviation 2.487	-3.194 breaths per minute Standard Deviation 3.589
Stress Recovery (Breathing Rate) for Older Adults Time 2	-4.046 breaths per minute Standard Deviation 4.169	-3.864 breaths per minute Standard Deviation 4.262

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

Difference in stress reactivity elicited by standard cognitive tasks, as assessed by change in systolic blood pressure from rest to cognitive tasks

Outcome measures

Measure	Younger HRV-increase Group n=51 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=45 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Stress Reactivity (Systolic Blood Pressure) for Younger Adults Time 1	3.090 mmHg Standard Deviation 10.659	1.424 mmHg Standard Deviation 8.867
Stress Reactivity (Systolic Blood Pressure) for Younger Adults Time 2	-0.729 mmHg Standard Deviation 8.402	1.812 mmHg Standard Deviation 7.864

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

Difference in stress reactivity elicited by standard cognitive tasks, as assessed by change in systolic blood pressure from rest to cognitive tasks

Outcome measures

Measure	Younger HRV-increase Group n=23 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=23 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Stress Reactivity (Systolic Blood Pressure) for Older Adults Time 2	6.553 mmHg Standard Deviation 12.311	0.043 mmHg Standard Deviation 11.351
Stress Reactivity (Systolic Blood Pressure) for Older Adults Time 1	6.303 mmHg Standard Deviation 12.349	6.196 mmHg Standard Deviation 12.727

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

Difference in stress reactivity elicited by standard cognitive tasks, as assessed by change in heart rate from rest to cognitive tasks

Outcome measures

Measure	Younger HRV-increase Group n=32 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=29 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Stress Reactivity (Heart Rate) for Younger Adults Time 1	4.270 beats per minute Standard Deviation 5.168	3.969 beats per minute Standard Deviation 5.085
Stress Reactivity (Heart Rate) for Younger Adults Time 2	2.060 beats per minute Standard Deviation 3.776	2.951 beats per minute Standard Deviation 4.242

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

Difference in stress reactivity elicited by standard cognitive tasks, as assessed by change in heart rate from cognitive tasks to recovery rest

Outcome measures

Measure	Younger HRV-increase Group n=14 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=18 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Stress Reactivity (Heart Rate) for Older Adults Time 1	3.991 beats per minute Standard Deviation 3.987	3.555 beats per minute Standard Deviation 2.138
Stress Reactivity (Heart Rate) for Older Adults Time 2	2.731 beats per minute Standard Deviation 2.977	1.951 beats per minute Standard Deviation 3.099

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

Difference in stress reactivity elicited by standard cognitive tasks, as assessed by change in breathing rate from rest to cognitive tasks

Outcome measures

Measure	Younger HRV-increase Group n=47 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=38 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Stress Reactivity (Breathing Rate) for Younger Adults Time 1	3.437 breaths per minute Standard Deviation 3.096	3.367 breaths per minute Standard Deviation 2.509
Stress Reactivity (Breathing Rate) for Younger Adults Time 2	4.381 breaths per minute Standard Deviation 4.082	2.235 breaths per minute Standard Deviation 2.023

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

Difference in stress reactivity elicited by standard cognitive tasks, as assessed by change in breathing rate from rest to cognitive tasks

Outcome measures

Measure	Younger HRV-increase Group n=19 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=18 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Stress Reactivity (Breathing Rate) for Older Adults Time 2	3.975 breaths per minute Standard Deviation 4.122	3.895 breaths per minute Standard Deviation 3.590
Stress Reactivity (Breathing Rate) for Older Adults Time 1	4.287 breaths per minute Standard Deviation 2.342	3.975 breaths per minute Standard Deviation 3.986

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

Cerebral blood flow was measured at pre-training resting state and post-training paced-breathing.

Outcome measures

Measure	Younger HRV-increase Group n=26 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=27 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Arterial Spin Labeling (ASL) for Younger Adults Time 1	44.01 mL/100 g/min Standard Error 1.68	40.96 mL/100 g/min Standard Error 1.53
Arterial Spin Labeling (ASL) for Younger Adults Time 2	39.69 mL/100 g/min Standard Error 1.61	38.98 mL/100 g/min Standard Error 1.48

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

Cerebral blood flow was measured at pre-training resting state and post-training paced-breathing.

Outcome measures

Measure	Younger HRV-increase Group n=13 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=17 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Arterial Spin Labeling (ASL) for Older Adults Time 2	30.95 mL/100 g/min Standard Error 2.02	39.93 mL/100 g/min Standard Error 1.89
Arterial Spin Labeling (ASL) for Older Adults Time 1	42.06 mL/100 g/min Standard Error 2.33	40.86 mL/100 g/min Standard Error 3.04

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

HRV measured by high frequency (HF) HRV for younger adults.

HF-HRV was quantified as the spectral power of interbeat interval variability within the high frequency range (typically 0.15-0.40 Hz), which reflects parasympathetic (vagal) activity. In this study, HF-HRV was obtained using photoplethysmography (PPG) methods. During a standardized resting condition, the device continuously recorded interbeat intervals. These data were then processed via spectral analysis to calculate the power in the high frequency band. Measurements are expressed in units of milliseconds squared (ms²). Higher HF-HRV values indicate increased parasympathetic modulation and are generally associated with improved autonomic regulation and better cognitive performance.

Outcome measures

Measure	Younger HRV-increase Group n=56 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=46 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
High Frequency (HF) HRV for Younger Adults Time 1	6.94 log transformed power(ms^2) Standard Deviation 1.13	6.77 log transformed power(ms^2) Standard Deviation 0.76
High Frequency (HF) HRV for Younger Adults Time 2	6.63 log transformed power(ms^2) Standard Deviation 1.01	6.62 log transformed power(ms^2) Standard Deviation 1.00

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

HRV measured by high frequency (HF) HRV for older adults.

HF-HRV was quantified as the spectral power of interbeat interval variability within the high frequency range (typically 0.15-0.40 Hz), which reflects parasympathetic (vagal) activity. In this study, HF-HRV was obtained using photoplethysmography (PPG) methods. During a standardized resting condition, the device continuously recorded interbeat intervals. These data were then processed via spectral analysis to calculate the power in the high frequency band. Measurements are expressed in units of milliseconds squared (ms²). Higher HF-HRV values indicate increased parasympathetic modulation and are generally associated with improved autonomic regulation and better cognitive performance.

Outcome measures

Measure	Younger HRV-increase Group n=25 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=28 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
High Frequency (HF) HRV for Older Adults Time 1	5.56 log transformed power(ms^2) Standard Deviation 0.89	5.40 log transformed power(ms^2) Standard Deviation 1.08
High Frequency (HF) HRV for Older Adults Time 2	5.78 log transformed power(ms^2) Standard Deviation 1.04	5.63 log transformed power(ms^2) Standard Deviation 1.16

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

HRV measured by low frequency (LF) HRV for younger adults.

LF-HRV was quantified as the spectral power of interbeat interval variability within the low frequency range (typically 0.04-0.15 Hz), which reflects the combined influences of sympathetic and parasympathetic activity. In this study, LF-HRV was obtained using photoplethysmography (PPG) methods. During a standardized resting condition, the device continuously recorded interbeat intervals. These data were then processed via spectral analysis to calculate the power in the low frequency band. Measurements are expressed in units of milliseconds squared (ms²). Although LF-HRV reflects contributions from both branches of the autonomic nervous system, higher LF-HRV values can indicate enhanced autonomic modulation, with interpretation made in the context of overall autonomic balance.

Outcome measures

Measure	Younger HRV-increase Group n=56 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=46 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Low Frequency (LF) HRV for Younger Adults Time 2	7.61 log transformed power(ms^2) Standard Deviation 1.21	6.75 log transformed power(ms^2) Standard Deviation 1.01
Low Frequency (LF) HRV for Younger Adults Time 1	7.25 log transformed power(ms^2) Standard Deviation 1.03	6.95 log transformed power(ms^2) Standard Deviation 0.93

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

HRV measured by low frequency (LF) HRV for older adults.

LF-HRV was quantified as the spectral power of interbeat interval variability within the low frequency range (typically 0.04-0.15 Hz), which reflects the combined influences of sympathetic and parasympathetic activity. In this study, LF-HRV was obtained using photoplethysmography (PPG) methods. During a standardized resting condition, the device continuously recorded interbeat intervals. These data were then processed via spectral analysis to calculate the power in the low frequency band. Measurements are expressed in units of milliseconds squared (ms²). Although LF-HRV reflects contributions from both branches of the autonomic nervous system, higher LF-HRV values can indicate enhanced autonomic modulation, with interpretation made in the context of overall autonomic balance.

Outcome measures

Measure	Younger HRV-increase Group n=25 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=28 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Low Frequency (LF) HRV for Older Adults Time 1	5.66 log transformed power(ms^2) Standard Deviation 1.19	5.14 log transformed power(ms^2) Standard Deviation 1.39
Low Frequency (LF) HRV for Older Adults Time 2	6.11 log transformed power(ms^2) Standard Deviation 1.49	5.31 log transformed power(ms^2) Standard Deviation 1.65

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

HRV measured by the root mean square of successive differences (RMSSD) for younger adults.

RMSSD (Root Mean Square of Successive Differences) is a time-domain measure that quantifies the variability between successive interbeat intervals, primarily reflecting parasympathetic (vagal) activity. In this study, RMSSD was obtained using photoplethysmography (PPG) methods. During a standardized resting condition, the device continuously recorded interbeat intervals, and RMSSD was computed as the square root of the mean of the squared differences between consecutive interbeat intervals. Measurements are expressed in milliseconds (ms). Higher RMSSD values indicate increased parasympathetic modulation, generally associated with improved autonomic regulation and better cardiovascular and cognitive performance.

Outcome measures

Measure	Younger HRV-increase Group n=56 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=46 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
The Root Mean Squared Successive Differences (RMSSD) HRV for Younger Adults Time 1	68.99 millisecond Standard Deviation 40.74	56.78 millisecond Standard Deviation 20.81
The Root Mean Squared Successive Differences (RMSSD) HRV for Younger Adults Time 2	60.99 millisecond Standard Deviation 28.36	61.78 millisecond Standard Deviation 42.66

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

HRV measured by the root mean square of successive differences (RMSSD) for older adults.

RMSSD (Root Mean Square of Successive Differences) is a time-domain measure that quantifies the variability between successive interbeat intervals, primarily reflecting parasympathetic (vagal) activity. In this study, RMSSD was obtained using photoplethysmography (PPG) methods. During a standardized resting condition, the device continuously recorded interbeat intervals, and RMSSD was computed as the square root of the mean of the squared differences between consecutive interbeat intervals. Measurements are expressed in milliseconds (ms). Higher RMSSD values indicate increased parasympathetic modulation, generally associated with improved autonomic regulation and better cardiovascular and cognitive performance.

Outcome measures

Measure	Younger HRV-increase Group n=25 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=28 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
The Root Mean Squared Successive Differences (RMSSD) HRV for Older Adults Time 1	33.99 millisecond Standard Deviation 16.87	33.39 millisecond Standard Deviation 15.07
The Root Mean Squared Successive Differences (RMSSD) HRV for Older Adults Time 2	42.17 millisecond Standard Deviation 26.05	39.09 millisecond Standard Deviation 20.55

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

Inflammation measured by salivary C-reactive protein (CRP) for younger adults

Outcome measures

Measure	Younger HRV-increase Group n=52 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=47 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Inflammation Measured by C-reactive Protein for Younger Adults Time 1	8193.259 CRP level (pg/ml) Standard Error 3905.210	4069.873 CRP level (pg/ml) Standard Error 4107.658
Inflammation Measured by C-reactive Protein for Younger Adults Time 2	6093.377 CRP level (pg/ml) Standard Error 3115.766	3985.363 CRP level (pg/ml) Standard Error 3277.311

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

Inflammation measured by salivary C-reactive protein (CRP) for older adults

Outcome measures

Measure	Younger HRV-increase Group n=14 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=14 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Inflammation Measured by C-reactive Protein for Older Adults Time 1	2809.771 CRP level (pg/ml) Standard Error 1063.422	864.984 CRP level (pg/ml) Standard Error 1063.422
Inflammation Measured by C-reactive Protein for Older Adults Time 2	1440.859 CRP level (pg/ml) Standard Error 437.418	509.761 CRP level (pg/ml) Standard Error 437.418

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

Inflammation measured by salivary IL-1b levels for younger adults

Outcome measures

Measure	Younger HRV-increase Group n=53 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=46 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Inflammation Measured by IL-1b Levels for Younger Adults Time 1	80.063 IL-1b level (pg/ml) Standard Error 15.825	91.827 IL-1b level (pg/ml) Standard Error 16.987
Inflammation Measured by IL-1b Levels for Younger Adults Time 2	86.474 IL-1b level (pg/ml) Standard Error 13.624	76.446 IL-1b level (pg/ml) Standard Error 14.624

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

Inflammation measured by salivary IL-1b levels for older adults

Outcome measures

Measure	Younger HRV-increase Group n=15 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=12 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Inflammation Measured by IL-1b Levels for Older Adults Time 1	218.580 IL-1b level (pg/ml) Standard Error 73.483	89.007 IL-1b level (pg/ml) Standard Error 82.157
Inflammation Measured by IL-1b Levels for Older Adults Time 2	174.882 IL-1b level (pg/ml) Standard Error 44.839	90.668 IL-1b level (pg/ml) Standard Error 50.131

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

Inflammation measured by salivary IL-6 levels for younger adults

Outcome measures

Measure	Younger HRV-increase Group n=53 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=46 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Inflammation Measured by IL-6 Levels for Younger Adults Time 1	4.653 IL-6 level (pg/ml) Standard Error 0.858	3.571 IL-6 level (pg/ml) Standard Error 0.921
Inflammation Measured by IL-6 Levels for Younger Adults Time 2	4.510 IL-6 level (pg/ml) Standard Error 0.884	3.029 IL-6 level (pg/ml) Standard Error 0.949

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

Inflammation measured by salivary IL-6 levels for older adults

Outcome measures

Measure	Younger HRV-increase Group n=15 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=12 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Inflammation Measured by IL-6 Levels for Older Adults Time 1	10.559 IL-6 level (pg/ml) Standard Error 4.439	7.595 IL-6 level (pg/ml) Standard Error 4.963
Inflammation Measured by IL-6 Levels for Older Adults Time 2	8.260 IL-6 level (pg/ml) Standard Error 2.108	4.605 IL-6 level (pg/ml) Standard Error 2.357

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

Inflammation measured by salivary IL-8 levels for younger adults

Outcome measures

Measure	Younger HRV-increase Group n=53 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=46 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Inflammation Measured by IL-8 Levels for Younger Adults Time 1	513.510 IL-8 level (pg/ml) Standard Error 89.567	540.543 IL-8 level (pg/ml) Standard Error 96.140
Inflammation Measured by IL-8 Levels for Younger Adults Time 2	448.990 IL-8 level (pg/ml) Standard Error 60.839	502.338 IL-8 level (pg/ml) Standard Error 65.304

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

Inflammation measured by salivary IL-8 levels for older adults

Outcome measures

Measure	Younger HRV-increase Group n=15 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=12 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Inflammation Measured by IL-8 Levels for Older Adults Time 1	1440.907 IL-8 level (pg/ml) Standard Error 270.644	656.653 IL-8 level (pg/ml) Standard Error 302.589
Inflammation Measured by IL-8 Levels for Older Adults Time 2	1343.894 IL-8 level (pg/ml) Standard Error 273.858	698.642 IL-8 level (pg/ml) Standard Error 306.182

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

Inflammation measured by salivary TNF-a levels for younger adults

Outcome measures

Measure	Younger HRV-increase Group n=53 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=46 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Inflammation Measured by TNF-a Levels for Younger Adults Time 1	2.792 TNF-a level (pg/ml) Standard Error 0.367	2.947 TNF-a level (pg/ml) Standard Error 0.394
Inflammation Measured by TNF-a Levels for Younger Adults Time 2	3.241 TNF-a level (pg/ml) Standard Error 0.411	2.202 TNF-a level (pg/ml) Standard Error 0.441

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

Inflammation measured by salivary TNF-a levels for older adults

Outcome measures

Measure	Younger HRV-increase Group n=15 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=12 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Inflammation Measured by TNF-a Levels for Older Adults Time 1	4.271 TNF-a level (pg/ml) Standard Error 0.945	1.607 TNF-a level (pg/ml) Standard Error 1.056
Inflammation Measured by TNF-a Levels for Older Adults Time 2	3.887 TNF-a level (pg/ml) Standard Error 0.985	2.338 TNF-a level (pg/ml) Standard Error 1.101

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Plasma Aβ40 levels at pre- and post-intervention were compared between HRV-increase and HRV-decrease group for younger adults.

Outcome measures

Measure	Younger HRV-increase Group n=30 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=24 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Plasma Amyloid Beta 40 (Aβ40) for Younger Adults Time 1 (pre-intervention)	166.95 pg/ml Standard Error 7.58	151.75 pg/ml Standard Error 4.95
Plasma Amyloid Beta 40 (Aβ40) for Younger Adults Time 2 (post-intervention)	150.25 pg/ml Standard Error 7.16	172.16 pg/ml Standard Error 7.87

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Plasma Aβ40 levels at pre- and post-intervention were compared between HRV-increase and HRV-decrease group for older adults.

Outcome measures

Measure	Younger HRV-increase Group n=27 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=27 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Plasma Amyloid Beta 40 (Aβ40) for Older Adults Time 1 (pre-intervention)	198.02 pg/ml Standard Error 9.15	211.76 pg/ml Standard Error 23.47
Plasma Amyloid Beta 40 (Aβ40) for Older Adults Time 2 (post-intervention)	189.95 pg/ml Standard Error 12.76	227.99 pg/ml Standard Error 19.85

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Plasma Aβ42 levels at pre- and post-intervention were compared between HRV-increase and HRV-decrease group for younger adults.

Outcome measures

Measure	Younger HRV-increase Group n=30 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=24 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Plasma Amyloid Beta 42 (Aβ42) Younger Adults Time 1 (pre-intervention)	9.77 pg/ml Standard Error 0.43	9.26 pg/ml Standard Error 0.47
Plasma Amyloid Beta 42 (Aβ42) Younger Adults Time 2 (post-intervention)	8.85 pg/ml Standard Error 0.46	10.84 pg/ml Standard Error 0.74

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Plasma Aβ42 levels at pre- and post-intervention were compared between HRV-increase and HRV-decrease group for older adults.

Outcome measures

Measure	Younger HRV-increase Group n=27 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=27 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Plasma Amyloid Beta 42 (Aβ42) for Older Adults Time 1 (pre-intervention)	10.78 pg/ml Standard Error 0.58	10.54 pg/ml Standard Error 0.75
Plasma Amyloid Beta 42 (Aβ42) for Older Adults Time 2 (post-intervention)	10.94 pg/ml Standard Error 0.62	11.80 pg/ml Standard Error 0.55

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Plasma pTau levels at pre- and post-intervention were reported for HRV-increase and HRV-decrease group for younger adults.

Outcome measures

Measure	Younger HRV-increase Group n=30 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=24 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Plasma Phosphorylated Tau 181 (pTau) for Younger Adults Time 1 (pre-intervention)	1.57 pg/ml Standard Error 0.12	1.57 pg/ml Standard Error 0.14
Plasma Phosphorylated Tau 181 (pTau) for Younger Adults Time 2 (post-intervention)	1.63 pg/ml Standard Error 0.12	1.66 pg/ml Standard Error 0.15

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Plasma pTau levels at pre- and post-intervention were compared between HRV-increase and HRV-decrease group for older adults.

Outcome measures

Measure	Younger HRV-increase Group n=27 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=27 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Plasma Phosphorylated Tau 181 (pTau) for Older Adults Time 1 (pre-intervention)	2.55 pg/ml Standard Error 0.22	2.94 pg/ml Standard Error 0.36
Plasma Phosphorylated Tau 181 (pTau) for Older Adults Time 2 (post-intervention)	2.64 pg/ml Standard Error 0.31	2.29 pg/ml Standard Error 0.26

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Plasma tTau levels at pre- and post-intervention were reported for HRV-increase and HRV-decrease group for younger adults.

Outcome measures

Measure	Younger HRV-increase Group n=30 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=24 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Plasma Total Tau (tTau) for Younger Adults Time 1 (pre-intervention)	2.13 pg/ml Standard Error 0.14	2.11 pg/ml Standard Error 0.16
Plasma Total Tau (tTau) for Younger Adults Time 2 (post-intervention)	1.87 pg/ml Standard Error 0.12	2.55 pg/ml Standard Error 0.20

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Plasma tTau levels at pre- and post-intervention were compared between HRV-increase and HRV-decrease group for older adults.

Outcome measures

Measure	Younger HRV-increase Group n=27 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=27 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Plasma Total Tau (tTau) for Older Adults Time 1 (pre-intervention)	1.91 pg/ml Standard Error 0.12	2.07 pg/ml Standard Error 0.17
Plasma Total Tau (tTau) for Older Adults Time 2 (post-intervention)	2.17 pg/ml Standard Error 0.22	2.13 pg/ml Standard Error 0.12

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

LC-innervated subregion volume in the hippocampus at pre- and post-intervention was compared between the HRV-increase and HRV-decrease groups in younger adults.

Outcome measures

Measure	Younger HRV-increase Group n=49 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=47 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
LC-innervated Subregion Volume in the Hippocampus for Younger Adults Time 1 (pre-intervention)	1177.99 mm^3 Standard Error 15.00	1142.29 mm^3 Standard Error 15.32
LC-innervated Subregion Volume in the Hippocampus for Younger Adults Time 2 (post-intervention)	1172.27 mm^3 Standard Error 15.01	1142.45 mm^3 Standard Error 15.33

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

LC-innervated subregion volume in the hippocampus at pre- and post-intervention was compared between the HRV-increase and HRV-decrease groups in older adults.

Outcome measures

Measure	Younger HRV-increase Group n=23 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=25 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
LC-innervated Subregion Volume in the Hippocampus for Older Adults Time 1 (pre-intervention)	1095.66 mm^3 Standard Error 23.58	1126.17 mm^3 Standard Error 22.62
LC-innervated Subregion Volume in the Hippocampus for Older Adults Time 2 (post-intervention)	1106.20 mm^3 Standard Error 24.18	1110.82 mm^3 Standard Error 22.62

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Left orbitofrontal volume at pre- and post-intervention was compared between the HRV-increase and HRV-decrease groups in younger adults.

Outcome measures

Measure	Younger HRV-increase Group n=49 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=47 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Cortical Volume in the Left Orbitofrontal Cortex for Younger Adults Time 1 (pre-intervention)	14001.81 mm^3 Standard Error 119.80	14024.90 mm^3 Standard Error 122.34
Cortical Volume in the Left Orbitofrontal Cortex for Younger Adults Time 2 (post-intervention)	14055.29 mm^3 Standard Error 125.81	13878.29 mm^3 Standard Error 128.47

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Left orbitofrontal volume at pre- and post-intervention was compared between the HRV-increase and HRV-decrease groups in older adults.

Outcome measures

Measure	Younger HRV-increase Group n=23 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=25 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Cortical Volume in the Left Orbitofrontal Cortex for Older Adults Time 1 (pre-intervention)	12369.59 mm^3 Standard Error 146.40	12391.75 mm^3 Standard Error 143.44
Cortical Volume in the Left Orbitofrontal Cortex for Older Adults Time 2 (post-intervention)	12452.50 mm^3 Standard Error 152.74	12290.84 mm^3 Standard Error 149.65

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Right orbitofrontal volume at pre- and post-intervention was compared between the HRV-increase and HRV-decrease groups in younger adults.

Outcome measures

Measure	Younger HRV-increase Group n=49 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=47 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Cortical Volume in the Right Orbitofrontal Cortex for Younger Adults Time 2 (post-intervention)	14233.22 mm^3 Standard Error 132.08	13898.56 mm^3 Standard Error 134.87
Cortical Volume in the Right Orbitofrontal Cortex for Younger Adults Time 1 (pre-intervention)	14231.64 mm^3 Standard Error 132.05	14005.03 mm^3 Standard Error 134.84

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Right orbitofrontal volume at pre- and post-intervention was compared between the HRV-increase and HRV-decrease groups in older adults.

Outcome measures

Measure	Younger HRV-increase Group n=23 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=25 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Cortical Volume in the Right Orbitofrontal Cortex for Older Adults Time 1 (pre-intervention)	12246.75 mm^3 Standard Error 150.82	12582.37 mm^3 Standard Error 147.77
Cortical Volume in the Right Orbitofrontal Cortex for Older Adults Time 2 (post-intervention)	12278.02 mm^3 Standard Error 157.55	12540.15 mm^3 Standard Error 154.36

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

The strength of resting-state functional connectivity between mPFC and the left amygdala was measured by correlation coefficients. The difference in functional connectivity between the two time points (Time 2 - Time 1) was calculated. Higher values indicate greater connectivity at Time 2 than Time 1 (or post- than pre-intervention).

Outcome measures

Measure	Younger HRV-increase Group n=49 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=47 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
mPFC-left Amygdala Resting-state Functional Connectivity for Younger Adults (Post-Pre)	0.093 correlation coefficients Standard Error 0.040	-0.018 correlation coefficients Standard Error 0.025

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

The strength of resting-state functional connectivity between mPFC and the left amygdala was measured by correlation coefficients. The difference in functional connectivity between the two time points (Time 2 - Time 1) was calculated. Higher values indicate greater connectivity at Time 2 than Time 1 (or post- than pre-intervention).

Outcome measures

Measure	Younger HRV-increase Group n=26 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=25 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
mPFC-left Amygdala Resting-state Functional Connectivity for Older Adults (Post-Pre)	0.002 correlation coefficients Standard Error 0.080	0.074 correlation coefficients Standard Error 0.051

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

The strength of resting-state functional connectivity was measured by correlation coefficients. Values represent the correlation of BOLD time-series between mPFC and the left amygdala. Higher values indicate greater connectivity.

Outcome measures

Measure	Younger HRV-increase Group n=49 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=47 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
mPFC-left Amygdala Resting-state Functional Connectivity for Younger Adults (ANOVA) Time 1	0.076 correlation coefficients Standard Error 0.021	0.089 correlation coefficients Standard Error 0.022
mPFC-left Amygdala Resting-state Functional Connectivity for Younger Adults (ANOVA) Time 2	0.168 correlation coefficients Standard Error 0.021	0.072 correlation coefficients Standard Error 0.021

SECONDARY outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

The strength of resting-state functional connectivity was measured by correlation coefficients. Values represent the correlation of BOLD time-series between mPFC and the left amygdala. Higher values indicate greater connectivity.

Outcome measures

Measure	Younger HRV-increase Group n=26 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=25 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
mPFC-left Amygdala Resting-state Functional Connectivity for Older Adults (ANOVA) Time 1	0.200 correlation coefficients Standard Error 0.050	0.079 correlation coefficients Standard Error 0.051
mPFC-left Amygdala Resting-state Functional Connectivity for Older Adults (ANOVA) Time 2	0.202 correlation coefficients Standard Error 0.048	0.153 correlation coefficients Standard Error 0.049

OTHER_PRE_SPECIFIED outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

Working memory performance measured by NIH Toolbox List Sorting Working Memory Test (LSWM). The standard score is calculated to have a normative mean of 100 and a standard deviation (SD) of 15. Scores range from 59 to 140, with higher scores indicating better Working memory.

Outcome measures

Measure	Younger HRV-increase Group n=56 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=49 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Working Memory for Younger Adults Time 1	98.39 age corrected standard score Standard Deviation 10.35	98.04 age corrected standard score Standard Deviation 14.00
Working Memory for Younger Adults Time 2	105.13 age corrected standard score Standard Deviation 10.39	103.10 age corrected standard score Standard Deviation 12.21

OTHER_PRE_SPECIFIED outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

Working memory performance measured by NIH Toolbox List Sorting Working Memory Test (LSWM).

The standard score is calculated to have a normative mean of 100 and a standard deviation (SD) of 15. Scores range from 59 to 140, with higher scores indicating better Working memory.

Outcome measures

Measure	Younger HRV-increase Group n=31 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=28 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Working Memory for Older Adults Time 1	102.48 age corrected standard score Standard Deviation 14.82	101.29 age corrected standard score Standard Deviation 14.14
Working Memory for Older Adults Time 2	103.06 age corrected standard score Standard Deviation 13.95	104.82 age corrected standard score Standard Deviation 11.16

OTHER_PRE_SPECIFIED outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

Processing speed performance measured by NIH Toolbox Pattern Comparison Processing Speed Test (PCPS).

The standard score is calculated to have a normative mean of 100 and a standard deviation (SD) of 15. Scores range from 59 to 140, with higher scores indicating faster processing speed.

Outcome measures

Measure	Younger HRV-increase Group n=56 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=49 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Processing Speed for Younger Adults Time 1	102.64 age corrected standard score Standard Deviation 22.69	105.55 age corrected standard score Standard Deviation 18.53
Processing Speed for Younger Adults Time 2	116.30 age corrected standard score Standard Deviation 17.72	118.51 age corrected standard score Standard Deviation 16.08

OTHER_PRE_SPECIFIED outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

Processing speed performance measured by NIH Toolbox Pattern Comparison Processing Speed Test (PCPS).

The standard score is calculated to have a normative mean of 100 and a standard deviation (SD) of 15. Scores range from 59 to 140, with higher scores indicating faster processing speed.

Outcome measures

Measure	Younger HRV-increase Group n=31 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=28 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Processing Speed for Older Adults Time 1	106.55 age corrected standard score Standard Deviation 21.10	98.54 age corrected standard score Standard Deviation 20.96
Processing Speed for Older Adults Time 2	107.68 age corrected standard score Standard Deviation 25.53	105.43 age corrected standard score Standard Deviation 17.57

OTHER_PRE_SPECIFIED outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

Inhibitory control performance measured by NIH Toolbox Flanker Inhibitory Control and Attention Test (Flanker).

The standard score is calculated to have a normative mean of 100 and a standard deviation (SD) of 15. Scores range from 59 to 140, with higher scores indicating better Inhibitory Control and Attention.

Outcome measures

Measure	Younger HRV-increase Group n=56 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=49 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Inhibitory Control and Attention for Younger Adults Time 1	87.27 age corrected standard score Standard Deviation 14.29	84.90 age corrected standard score Standard Deviation 12.17
Inhibitory Control and Attention for Younger Adults Time 2	89.21 age corrected standard score Standard Deviation 15.03	88.71 age corrected standard score Standard Deviation 11.96

OTHER_PRE_SPECIFIED outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

Inhibitory control performance measured by NIH Toolbox Flanker Inhibitory Control and Attention Test (Flanker).

The standard score is calculated to have a normative mean of 100 and a standard deviation (SD) of 15. Scores range from 59 to 140, with higher scores indicating better Inhibitory Control and Attention.

Outcome measures

Measure	Younger HRV-increase Group n=31 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=28 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Inhibitory Control and Attention for Older Adults Time 1	90.84 age corrected standard score Standard Deviation 8.91	89.82 age corrected standard score Standard Deviation 11.17
Inhibitory Control and Attention for Older Adults Time 2	93.29 age corrected standard score Standard Deviation 8.76	92.04 age corrected standard score Standard Deviation 13.44

OTHER_PRE_SPECIFIED outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

Sustained attention performance was measured by Sustained Attention to Response Test (SART).

A commission error was calculated as the number of button press for 25 no-go trials, and an omission error was calculated as the number of no button press for 200 go trials in younger adults. The number of errors range from 0 to 25 for commission errors and from 0 to 200 for omission errors. A higher number of omission and commission errors indicates worse sustained attention performance.

Outcome measures

Measure	Younger HRV-increase Group n=53 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=47 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Sustained Attention for Younger Adults Time 2: commission error	9.830 number of errors Standard Error 1.041	9.851 number of errors Standard Error 1.106
Sustained Attention for Younger Adults Time 1: commission error	12.679 number of errors Standard Error 0.936	12.979 number of errors Standard Error 0.994
Sustained Attention for Younger Adults Time 1: omission error	1.906 number of errors Standard Error 0.592	3.383 number of errors Standard Error 0.628
Sustained Attention for Younger Adults Time 2: omission error	1.792 number of errors Standard Error 0.541	2.383 number of errors Standard Error 0.574

OTHER_PRE_SPECIFIED outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

Sustained attention performance was measured by Sustained Attention to Response Test (SART).

A commission error was calculated as the number of button press for 25 no-go trials, and an omission error was calculated as the number of no button press for 200 go trials in older adults. The number of errors range from 0 to 25 for commission errors and from 0 to 200 for omission errors. A higher number of omission and commission errors indicates worse sustained attention performance.

Outcome measures

Measure	Younger HRV-increase Group n=26 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=19 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Sustained Attention for Older Adults Time 2: commission error	8.692 number of errors Standard Error 1.152	8.789 number of errors Standard Error 1.347
Sustained Attention for Older Adults Time 1: omission error	3.731 number of errors Standard Error 1.187	4.947 number of errors Standard Error 1.389
Sustained Attention for Older Adults Time 2: omission error	1.731 number of errors Standard Error 0.765	2.842 number of errors Standard Error 0.894
Sustained Attention for Older Adults Time 1: commission error	9.538 number of errors Standard Error 1.172	9.211 number of errors Standard Error 1.371

OTHER_PRE_SPECIFIED outcome

Timeframe: Week 5 Lab Visit (after about 2.5-3 weeks of training)

Population: Population analyzed was composed by all randomization subjects who completed the memory tests and whose data quality was sufficient for data analysis.

Recognition memory performance based on average proportion of previously presented images that were correctly identified (i.e., hits) by younger adults

Outcome measures

Measure	Younger HRV-increase Group n=55 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=50 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Recognition Memory for Younger Adults (Hits) Neutral	.880 Proportion of correct hits Standard Error .014	.873 Proportion of correct hits Standard Error .013
Recognition Memory for Younger Adults (Hits) Positive	.886 Proportion of correct hits Standard Error .012	.866 Proportion of correct hits Standard Error .011
Recognition Memory for Younger Adults (Hits) Negative	.914 Proportion of correct hits Standard Error .011	.900 Proportion of correct hits Standard Error .012

OTHER_PRE_SPECIFIED outcome

Timeframe: Week 5 Lab Visit (after about 2.5-3 weeks of training)

Population: Population analyzed was composed by all randomization subjects who completed the memory tests and whose data quality was sufficient for data analysis.

Recognition memory performance based on average proportion of previously presented images that were correctly identified (i.e., hits) by older adults

Outcome measures

Measure	Younger HRV-increase Group n=29 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=31 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Recognition Memory for Older Adults (Hits) Positive	.820 Proportion of correct hits Standard Error .022	.851 Proportion of correct hits Standard Error .016
Recognition Memory for Older Adults (Hits) Negative	.875 Proportion of correct hits Standard Error .017	.870 Proportion of correct hits Standard Error .014
Recognition Memory for Older Adults (Hits) Neutral	.828 Proportion of correct hits Standard Error .020	.859 Proportion of correct hits Standard Error .015

OTHER_PRE_SPECIFIED outcome

Timeframe: Week 5 Lab Visit (after about 2.5-3 weeks of training)

Population: Population analyzed was composed by all randomization subjects who completed the memory tests and whose data quality was sufficient for data analysis.

Recognition memory performance based on average proportion of images not previously presented that were incorrectly identified as seen (i.e., False Alarms) by younger adults

Outcome measures

Measure	Younger HRV-increase Group n=55 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=50 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Recognition Memory for Younger Adults (False Alarm) Neutral	.048 Proportion of false alarm Standard Error .007	.042 Proportion of false alarm Standard Error .006
Recognition Memory for Younger Adults (False Alarm) Positive	.044 Proportion of false alarm Standard Error .008	.046 Proportion of false alarm Standard Error .008
Recognition Memory for Younger Adults (False Alarm) Negative	.027 Proportion of false alarm Standard Error .005	.041 Proportion of false alarm Standard Error .007

OTHER_PRE_SPECIFIED outcome

Timeframe: Week 5 Lab Visit (after about 2.5-3 weeks of training)

Population: Population analyzed was composed by all randomization subjects who completed the memory tests and whose data quality was sufficient for data analysis.

Recognition memory performance based on average proportion of images not previously presented that were incorrectly identified as seen (i.e., False Alarms) by older adults

Outcome measures

Measure	Younger HRV-increase Group n=29 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=31 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Recognition Memory for Older Adults (False Alarm) Neutral	.091 Proportion of false alarms Standard Error .017	.047 Proportion of false alarms Standard Error .011
Recognition Memory for Older Adults (False Alarm) Positive	.093 Proportion of false alarms Standard Error .018	.062 Proportion of false alarms Standard Error .011
Recognition Memory for Older Adults (False Alarm) Negative	.069 Proportion of false alarms Standard Error .012	.052 Proportion of false alarms Standard Error .011

OTHER_PRE_SPECIFIED outcome

Timeframe: Week 5 Lab Visit (after about 2.5-3 weeks of training)

Population: Population analyzed was composed by all randomization subjects who completed the memory tests and whose data quality was sufficient for data analysis.

Average proportion of previously presented images that were correctly recalled by younger adults

Outcome measures

Measure	Younger HRV-increase Group n=52 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=50 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Recall Memory for Younger Adults Positive	.285 Proportion of items correctly recalled Standard Error .023	.214 Proportion of items correctly recalled Standard Error .023
Recall Memory for Younger Adults Negative	.248 Proportion of items correctly recalled Standard Error .020	.262 Proportion of items correctly recalled Standard Error .027

OTHER_PRE_SPECIFIED outcome

Timeframe: Week 5 Lab Visit (after about 2.5-3 weeks of training)

Population: Population analyzed was composed by all randomization subjects who completed the memory tests and whose data quality was sufficient for data analysis.

Average proportion of previously presented images that were correctly recalled by older adults

Outcome measures

Measure	Younger HRV-increase Group n=27 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=28 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Recall Memory for Older Adults Positive	.203 Proportion of items correctly recalled Standard Error .030	.156 Proportion of items correctly recalled Standard Error .025
Recall Memory for Older Adults Negative	.225 Proportion of items correctly recalled Standard Error .036	.286 Proportion of items correctly recalled Standard Error .040

OTHER_PRE_SPECIFIED outcome

Timeframe: Time 1 (Baseline), Time 2 (5 weeks)

Population: Population analyzed was composed by all randomization subjects who completed pre- and post-intervention assessments and whose data quality was sufficient for data analysis.

Stress measured by salivary cortisol levels for younger adults

Outcome measures

Measure	Younger HRV-increase Group n=50 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to increase their heart rate variability (HRV) for 5 weeks.	Younger HRV-decrease Group n=44 Participants Participants in this group were between the ages of 18 and 35. Half of the younger participants were randomly assigned to this group and underwent daily practice to decrease their heart rate variability (HRV) for 5 weeks.
Stress Measured by Cortisol Levels for Younger Adults Time 1: cortisol level at awakening	0.231 CAR level (µg/dL) Standard Error 0.023	0.248 CAR level (µg/dL) Standard Error 0.024
Stress Measured by Cortisol Levels for Younger Adults Time 1: cortisol level at 30 min after awakening	0.431 CAR level (µg/dL) Standard Error 0.035	0.453 CAR level (µg/dL) Standard Error 0.037
Stress Measured by Cortisol Levels for Younger Adults Time 2: cortisol level at awakening	0.284 CAR level (µg/dL) Standard Error 0.033	0.309 CAR level (µg/dL) Standard Error 0.035
Stress Measured by Cortisol Levels for Younger Adults Time 2: cortisol level at 30 min after awakening	0.478 CAR level (µg/dL) Standard Error 0.045	0.472 CAR level (µg/dL) Standard Error 0.048

Adverse Events

Younger HRV-increase Group

Serious events: 0 serious events

Other events: 0 other events

Deaths: 0 deaths

Younger HRV-decrease Group

Serious events: 0 serious events

Other events: 0 other events

Deaths: 0 deaths

Older HRV-increase Group

Serious events: 0 serious events

Other events: 0 other events

Deaths: 0 deaths

Older HRV-decrease Group

Serious events: 0 serious events

Other events: 0 other events

Deaths: 0 deaths

Serious adverse events

Adverse event data not reported

Other adverse events

Adverse event data not reported

Additional Information

Dr. Mara Mather

University of Southern California

Phone: (213) 821-1868

Email: mara.mather@usc.edu

Results disclosure agreements

• Principal investigator is a sponsor employee
• Publication restrictions are in place