Trial Outcomes & Findings for Maximizing the Impact of Neuroplasticity Using Transcranial Electrical Stimulation Study 1 (NCT NCT03896425)

NCT ID: NCT03896425

Last Updated: 2024-08-07

Results Overview

Most participants completed MRI sessions on a 3T scanner located in the Center for Magnetic Resonance Research (CMRR) at the University of Minnesota. FC measures how different brain regions change in activation together. We characterized FC using global connectivity from graph theory analysis. We extracted the fMRI time courses from 454 parcellations defined by the 400 S4 Schaefer Atlas (Schaefer et al., 2018) combined with the Melbourne Subcortex Atlas (Tian et al., 2020). We computed the absolute value of the Pearson's correlation for all possible pairs of time series, creating a 454x454 (N x N) connectivity matrix, which was then reduced to 10% most significant connections by subject. We estimated the FC by calculating the node strength for each parcellation, which is the weighted mean of all significant connections, from these connectivity matrices. Finally, we averaged node strength across parcellations to calculate global node strength. Higher values indicate more brain-wide FC.

• Recruitment status: COMPLETED
• Study phase: NA
• Target enrollment: 73 participants
• Primary outcome timeframe: baseline
• Results posted on: 2024-08-07

Participant Flow

Participant milestones

Measure	Right Active-tDCS 2-3 times/week for 12 weeks: ramp-up for 30 seconds, 2mA right (AF4 anode - AF3 cathode) for 20 min, and then ramp-down for 30 seconds. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.	Left Active-tDCS 2-3 times/week for 12 weeks: ramp-up for 30 seconds, 2mA left (AF3 anode - AF4 cathode) for 20 min, and then ramp-down for 30 seconds. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.	Sham tDCS Current will be turned off immediately after the initial 30-second ramp-up period. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.
Overall Study STARTED	20	18	20
Overall Study COMPLETED	13	10	15
Overall Study NOT COMPLETED	7	8	5

Reasons for withdrawal

Withdrawal data not reported

Baseline Characteristics

Maximizing the Impact of Neuroplasticity Using Transcranial Electrical Stimulation Study 1

Baseline characteristics by cohort

Measure	Right Active-tDCS n=20 Participants 2-3 times/week for 12 weeks: ramp-up for 30 seconds, 2mA right (AF4 anode - AF3 cathode) for 20 min, and then ramp-down for 30 seconds. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.	Left Active-tDCS n=18 Participants 2-3 times/week for 12 weeks: ramp-up for 30 seconds, 2mA left (AF3 anode - AF4 cathode) for 20 min, and then ramp-down for 30 seconds. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.	Sham tDCS n=20 Participants Current will be turned off immediately after the initial 30-second ramp-up period. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.	Total n=58 Participants Total of all reporting groups
Age, Categorical <=18 years	0 Participants n=93 Participants	0 Participants n=4 Participants	0 Participants n=27 Participants	0 Participants n=483 Participants
Age, Categorical Between 18 and 65 years	20 Participants n=93 Participants	18 Participants n=4 Participants	20 Participants n=27 Participants	58 Participants n=483 Participants
Age, Categorical >=65 years	0 Participants n=93 Participants	0 Participants n=4 Participants	0 Participants n=27 Participants	0 Participants n=483 Participants
Age, Continuous	22.9 YEARS STANDARD_DEVIATION 5.3 • n=93 Participants	26.6 YEARS STANDARD_DEVIATION 8.2 • n=4 Participants	24.9 YEARS STANDARD_DEVIATION 8.9 • n=27 Participants	24.7 YEARS STANDARD_DEVIATION 7.6 • n=483 Participants
Sex/Gender, Customized Female	7 Participants n=93 Participants	9 Participants n=4 Participants	6 Participants n=27 Participants	22 Participants n=483 Participants
Sex/Gender, Customized Male	13 Participants n=93 Participants	8 Participants n=4 Participants	14 Participants n=27 Participants	35 Participants n=483 Participants
Sex/Gender, Customized Nonbinary	0 Participants n=93 Participants	1 Participants n=4 Participants	0 Participants n=27 Participants	1 Participants n=483 Participants
Race (NIH/OMB) American Indian or Alaska Native	0 Participants n=93 Participants	0 Participants n=4 Participants	0 Participants n=27 Participants	0 Participants n=483 Participants
Race (NIH/OMB) Asian	4 Participants n=93 Participants	0 Participants n=4 Participants	4 Participants n=27 Participants	8 Participants n=483 Participants
Race (NIH/OMB) Native Hawaiian or Other Pacific Islander	0 Participants n=93 Participants	0 Participants n=4 Participants	0 Participants n=27 Participants	0 Participants n=483 Participants
Race (NIH/OMB) Black or African American	1 Participants n=93 Participants	1 Participants n=4 Participants	0 Participants n=27 Participants	2 Participants n=483 Participants
Race (NIH/OMB) White	15 Participants n=93 Participants	15 Participants n=4 Participants	14 Participants n=27 Participants	44 Participants n=483 Participants
Race (NIH/OMB) More than one race	0 Participants n=93 Participants	2 Participants n=4 Participants	2 Participants n=27 Participants	4 Participants n=483 Participants
Race (NIH/OMB) Unknown or Not Reported	0 Participants n=93 Participants	0 Participants n=4 Participants	0 Participants n=27 Participants	0 Participants n=483 Participants

PRIMARY outcome

Timeframe: baseline

Most participants completed MRI sessions on a 3T scanner located in the Center for Magnetic Resonance Research (CMRR) at the University of Minnesota. FC measures how different brain regions change in activation together. We characterized FC using global connectivity from graph theory analysis. We extracted the fMRI time courses from 454 parcellations defined by the 400 S4 Schaefer Atlas (Schaefer et al., 2018) combined with the Melbourne Subcortex Atlas (Tian et al., 2020). We computed the absolute value of the Pearson's correlation for all possible pairs of time series, creating a 454x454 (N x N) connectivity matrix, which was then reduced to 10% most significant connections by subject. We estimated the FC by calculating the node strength for each parcellation, which is the weighted mean of all significant connections, from these connectivity matrices. Finally, we averaged node strength across parcellations to calculate global node strength. Higher values indicate more brain-wide FC.

Outcome measures

Measure	Right Active-tDCS n=20 Participants 2-3 times/week for 12 weeks: ramp-up for 30 seconds, 2mA right (AF4 anode - AF3 cathode) for 20 min, and then ramp-down for 30 seconds. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.	Left Active-tDCS n=18 Participants 2-3 times/week for 12 weeks: ramp-up for 30 seconds, 2mA left (AF3 anode - AF4 cathode) for 20 min, and then ramp-down for 30 seconds. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.	Sham tDCS n=20 Participants Current will be turned off immediately after the initial 30-second ramp-up period. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.
Changes in Thalamocortical Functional Connectivity (FC)	22.7 arbitrary units Standard Deviation 4.0	20.5 arbitrary units Standard Deviation 4.0	21.9 arbitrary units Standard Deviation 2.8

PRIMARY outcome

Timeframe: baseline

Task-dependent thalamocortical connectivity associated with the N-back task was calculated by modeling the block task design together with the thalamic regressor using psychophysiological interaction analysis (PPI). The thalamic regressor is the time series of the mediodorsal thalamus from the Melbourne atlas. The primary analysis focused on the 2-back conditions alone. The PPI analysis calculates the functional connectivity between the mediodorsal thalamus and all other brain regions specifically during 2-back trials. Neural activation related to the thalamic regressor was compared to neural activation during the fixation (no choices made) to normalize the relative activation (z-score). Positive values indicate increased functional connectivity with the thalamus during the 2-back choices. A z-score of zero represents no difference compared to the fixation cross (no choices). We report the average z-score of the PPI regressor within the control network (Yeo et al., 2011).

Outcome measures

Measure	Right Active-tDCS n=20 Participants 2-3 times/week for 12 weeks: ramp-up for 30 seconds, 2mA right (AF4 anode - AF3 cathode) for 20 min, and then ramp-down for 30 seconds. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.	Left Active-tDCS n=16 Participants 2-3 times/week for 12 weeks: ramp-up for 30 seconds, 2mA left (AF3 anode - AF4 cathode) for 20 min, and then ramp-down for 30 seconds. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.	Sham tDCS n=20 Participants Current will be turned off immediately after the initial 30-second ramp-up period. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.
Changes in Task-dependent Thalamocortical Functional Connectivity (fMRI) During the N-back Task.	-0.58 z-score Standard Deviation 0.58	-0.27 z-score Standard Deviation 0.48	-0.29 z-score Standard Deviation 0.34

PRIMARY outcome

Timeframe: baseline

Task-dependent thalamocortical connectivity associated with the Dot Pattern Expectancy (DPX) task demands will be identified by analyzing cue and probe events together with the thalamic regressor using psychophysiological interaction analysis (PPI). The thalamic regressor is the time series of the mediodorsal thalamus from the Melbourne atlas. We examined B-cue related connectivity. The PPI analysis calculates the functional connectivity between the mediodorsal thalamus and all other brain regions specifically during B-cue trials. Neural activation related to the thalamic regressor was compared to neural activation during the fixation (no choices made) to normalize the relative activation (z-score). Positive values indicate increased functional connectivity with the thalamus during the B-cue responses. A z-score of zero represents no difference compared to the fixation cross (no choices). We report the average z-score of the PPI regressor within the control network (Yeo et al., 2011).

Outcome measures

Measure	Right Active-tDCS n=19 Participants 2-3 times/week for 12 weeks: ramp-up for 30 seconds, 2mA right (AF4 anode - AF3 cathode) for 20 min, and then ramp-down for 30 seconds. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.	Left Active-tDCS n=18 Participants 2-3 times/week for 12 weeks: ramp-up for 30 seconds, 2mA left (AF3 anode - AF4 cathode) for 20 min, and then ramp-down for 30 seconds. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.	Sham tDCS n=20 Participants Current will be turned off immediately after the initial 30-second ramp-up period. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.
Changes in Task-dependent Thalamocortical Functional Connectivity (fMRI) During the DPX Task.	-0.13 z-score Standard Deviation 0.49	-0.14 z-score Standard Deviation 0.32	-0.18 z-score Standard Deviation 0.36

PRIMARY outcome

Timeframe: baseline

The n-back task measures working memory capacity. The participant is presented with a series of stimuli and instructed to indicate with a button press when the current stimulus matches the stimulus that appeared a pre-determined number (n) of trials before. d' (d prime) will be calculated as a measure of signal detection, which indicates the normalized rate of hits to false positives (d' = z(H) - z(F)). Increase in d' signifies improved signal detection, i.e. a better outcome. A d' near zero indicates a performance at chance, i.e., a poor performance.

Outcome measures

Measure	Right Active-tDCS n=20 Participants 2-3 times/week for 12 weeks: ramp-up for 30 seconds, 2mA right (AF4 anode - AF3 cathode) for 20 min, and then ramp-down for 30 seconds. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.	Left Active-tDCS n=18 Participants 2-3 times/week for 12 weeks: ramp-up for 30 seconds, 2mA left (AF3 anode - AF4 cathode) for 20 min, and then ramp-down for 30 seconds. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.	Sham tDCS n=20 Participants Current will be turned off immediately after the initial 30-second ramp-up period. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.
D-prime Score	2.45 arbitrary units Standard Deviation 0.95	2.34 arbitrary units Standard Deviation 0.58	2.66 arbitrary units Standard Deviation 0.93

PRIMARY outcome

Timeframe: baseline

The Dot Pattern Expectancy (DPX) task is an adaptation of the expectancy AX task that uses pairs of simple dot patterns rather than letter pairs as stimuli. The DPX task will be performed in 3 blocks. Each trial consists of a cue dot pattern followed by a probe dot pattern. Different combinations of cues and probes enable the identification of a specific deficit in a subject's ability to maintain goal-relevant information throughout a trial. Timing will be jittered and each block of the DPX task will consist of 40 trials: 24 AX (60%), 6 AY (15%), 6 BX (15%) and 4 BY (10%). Each block will last 6 minutes. d'-context will be calculated as a measure of signal detection, which indicates the normalized rate of AX hits to BX false positives (d' = z(H) - z(F)). Increase in d' -context signified improved signal detection, i.e. a better outcome. A d' near zero indicates a performance at chance, i.e., a poor performance.

Outcome measures

Measure	Right Active-tDCS n=20 Participants 2-3 times/week for 12 weeks: ramp-up for 30 seconds, 2mA right (AF4 anode - AF3 cathode) for 20 min, and then ramp-down for 30 seconds. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.	Left Active-tDCS n=18 Participants 2-3 times/week for 12 weeks: ramp-up for 30 seconds, 2mA left (AF3 anode - AF4 cathode) for 20 min, and then ramp-down for 30 seconds. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.	Sham tDCS n=20 Participants Current will be turned off immediately after the initial 30-second ramp-up period. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.
D-prime Score	3.47 arbitrary units Standard Deviation 0.88	3.36 arbitrary units Standard Deviation 0.75	3.10 arbitrary units Standard Deviation 0.91

PRIMARY outcome

Timeframe: baseline

Intends to provide a relatively brief evaluation of key cognitive domains relevant to schizophrenia and related disorders. The composite score is reported as a T-score, with a mean of 50 and standard deviation of 10. Higher values indicate greater cognitive functioning.

Outcome measures

Measure	Right Active-tDCS n=20 Participants 2-3 times/week for 12 weeks: ramp-up for 30 seconds, 2mA right (AF4 anode - AF3 cathode) for 20 min, and then ramp-down for 30 seconds. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.	Left Active-tDCS n=17 Participants 2-3 times/week for 12 weeks: ramp-up for 30 seconds, 2mA left (AF3 anode - AF4 cathode) for 20 min, and then ramp-down for 30 seconds. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.	Sham tDCS n=20 Participants Current will be turned off immediately after the initial 30-second ramp-up period. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.
Changes in Measurement and Treatment Research to Improve Cognition in Schizophrenia (MATRICS) Consensus Cognitive Battery (MCCB) Composite Score	53.3 T-score Standard Deviation 11.1	53.6 T-score Standard Deviation 6.01	54 T-score Standard Deviation 11.9

PRIMARY outcome

Timeframe: mid-test (week 6)

Most participants completed MRI sessions on a 3T scanner located in the Center for Magnetic Resonance Research (CMRR) at the University of Minnesota. FC measures how different brain regions change in activation together. We characterized FC using global connectivity from graph theory analysis. We extracted the fMRI time courses from 454 parcellations defined by the 400 S4 Schaefer Atlas (Schaefer et al., 2018) combined with the Melbourne Subcortex Atlas (Tian et al., 2020). We computed the absolute value of the Pearson's correlation for all possible pairs of time series, creating a 454x454 (N x N) connectivity matrix, which was then reduced to 10% most significant connections by subject. We estimated the FC by calculating the node strength for each parcellation, which is the weighted mean of all significant connections, from these connectivity matrices. Finally, we averaged node strength across parcellations to calculate global node strength. Higher values indicate more brain-wide FC.

Outcome measures

Measure	Right Active-tDCS n=16 Participants 2-3 times/week for 12 weeks: ramp-up for 30 seconds, 2mA right (AF4 anode - AF3 cathode) for 20 min, and then ramp-down for 30 seconds. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.	Left Active-tDCS n=10 Participants 2-3 times/week for 12 weeks: ramp-up for 30 seconds, 2mA left (AF3 anode - AF4 cathode) for 20 min, and then ramp-down for 30 seconds. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.	Sham tDCS n=17 Participants Current will be turned off immediately after the initial 30-second ramp-up period. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.
Changes in Thalamocortical Functional Connectivity (FC)	23 arbitrary units Standard Deviation 4.3	20.3 arbitrary units Standard Deviation 2.8	23.8 arbitrary units Standard Deviation 3.5

PRIMARY outcome

Timeframe: post-test (week 12)

Most participants completed MRI sessions on a 3T scanner located in the Center for Magnetic Resonance Research (CMRR) at the University of Minnesota. FC measures how different brain regions change in activation together. We characterized FC using global connectivity from graph theory analysis. We extracted the fMRI time courses from 454 parcellations defined by the 400 S4 Schaefer Atlas (Schaefer et al., 2018) combined with the Melbourne Subcortex Atlas (Tian et al., 2020). We computed the absolute value of the Pearson's correlation for all possible pairs of time series, creating a 454x454 (N x N) connectivity matrix, which was then reduced to 10% most significant connections by subject. We estimated the FC by calculating the node strength for each parcellation, which is the weighted mean of all significant connections, from these connectivity matrices. Finally, we averaged node strength across parcellations to calculate global node strength. Higher values indicate more brain-wide FC.

Outcome measures

Measure	Right Active-tDCS n=14 Participants 2-3 times/week for 12 weeks: ramp-up for 30 seconds, 2mA right (AF4 anode - AF3 cathode) for 20 min, and then ramp-down for 30 seconds. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.	Left Active-tDCS n=9 Participants 2-3 times/week for 12 weeks: ramp-up for 30 seconds, 2mA left (AF3 anode - AF4 cathode) for 20 min, and then ramp-down for 30 seconds. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.	Sham tDCS n=15 Participants Current will be turned off immediately after the initial 30-second ramp-up period. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.
Changes in Thalamocortical Functional Connectivity (FC)	23.1 arbitrary units Standard Deviation 4.7	19.8 arbitrary units Standard Deviation 4.0	24.2 arbitrary units Standard Deviation 3.5

PRIMARY outcome

Timeframe: mid-test (week 6)

Task-dependent thalamocortical connectivity associated with the N-back task was calculated by modeling the block task design together with the thalamic regressor using psychophysiological interaction analysis (PPI). The thalamic regressor is the time series of the mediodorsal thalamus from the Melbourne atlas. The primary analysis focused on the 2-back conditions alone. The PPI analysis calculates the functional connectivity between the mediodorsal thalamus and all other brain regions specifically during 2-back trials. Neural activation related to the thalamic regressor was compared to neural activation during the fixation (no choices made) to normalize the relative activation (z-score). Positive values indicate increased functional connectivity with the thalamus during the 2-back choices. A z-score of zero represents no difference compared to the fixation cross (no choices). We report the average z-score of the PPI regressor within the control network (Yeo et al., 2011).

Outcome measures

Measure	Right Active-tDCS n=16 Participants 2-3 times/week for 12 weeks: ramp-up for 30 seconds, 2mA right (AF4 anode - AF3 cathode) for 20 min, and then ramp-down for 30 seconds. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.	Left Active-tDCS n=9 Participants 2-3 times/week for 12 weeks: ramp-up for 30 seconds, 2mA left (AF3 anode - AF4 cathode) for 20 min, and then ramp-down for 30 seconds. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.	Sham tDCS n=17 Participants Current will be turned off immediately after the initial 30-second ramp-up period. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.
Changes in Task-dependent Thalamocortical Functional Connectivity (fMRI) During the N-back Task.	-0.33 z-score Standard Deviation 0.51	0.09 z-score Standard Deviation 0.54	-0.44 z-score Standard Deviation 0.44

PRIMARY outcome

Timeframe: post-test (week 12)

Task-dependent thalamocortical connectivity associated with the N-back task was calculated by modeling the block task design together with the thalamic regressor using psychophysiological interaction analysis (PPI). The thalamic regressor is the time series of the mediodorsal thalamus from the Melbourne atlas. The primary analysis focused on the 2-back conditions alone. The PPI analysis calculates the functional connectivity between the mediodorsal thalamus and all other brain regions specifically during 2-back trials. Neural activation related to the thalamic regressor was compared to neural activation during the fixation (no choices made) to normalize the relative activation (z-score). Positive values indicate increased functional connectivity with the thalamus during the 2-back choices. A z-score of zero represents no difference compared to the fixation cross (no choices). We report the average z-score of the PPI regressor within the control network (Yeo et al., 2011).

Outcome measures

Measure	Right Active-tDCS n=14 Participants 2-3 times/week for 12 weeks: ramp-up for 30 seconds, 2mA right (AF4 anode - AF3 cathode) for 20 min, and then ramp-down for 30 seconds. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.	Left Active-tDCS n=9 Participants 2-3 times/week for 12 weeks: ramp-up for 30 seconds, 2mA left (AF3 anode - AF4 cathode) for 20 min, and then ramp-down for 30 seconds. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.	Sham tDCS n=15 Participants Current will be turned off immediately after the initial 30-second ramp-up period. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.
Changes in Task-dependent Thalamocortical Functional Connectivity (fMRI) During the N-back Task.	-0.24 z-score Standard Deviation 0.48	-0.38 z-score Standard Deviation 0.42	-0.4 z-score Standard Deviation 0.49

PRIMARY outcome

Timeframe: mid-test (week 6)

The n-back task measures working memory capacity. The participant is presented with a series of stimuli and instructed to indicate with a button press when the current stimulus matches the stimulus that appeared a pre-determined number (n) of trials before. d' (d prime) will be calculated as a measure of signal detection, which indicates the normalized rate of hits to false positives (d' = z(H) - z(F)). Increase in d' signifies improved signal detection, i.e. a better outcome. A d' near zero indicates a performance at chance, i.e., a poor performance.

Outcome measures

Measure	Right Active-tDCS n=16 Participants 2-3 times/week for 12 weeks: ramp-up for 30 seconds, 2mA right (AF4 anode - AF3 cathode) for 20 min, and then ramp-down for 30 seconds. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.	Left Active-tDCS n=10 Participants 2-3 times/week for 12 weeks: ramp-up for 30 seconds, 2mA left (AF3 anode - AF4 cathode) for 20 min, and then ramp-down for 30 seconds. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.	Sham tDCS n=17 Participants Current will be turned off immediately after the initial 30-second ramp-up period. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.
D-prime Score	3.24 arbitrary units Standard Deviation 0.74	3.07 arbitrary units Standard Deviation 0.52	3 arbitrary units Standard Deviation 1.05

PRIMARY outcome

Timeframe: post-test (week 12)

The n-back task measures working memory capacity. The participant is presented with a series of stimuli and instructed to indicate with a button press when the current stimulus matches the stimulus that appeared a pre-determined number (n) of trials before. d' (d prime) will be calculated as a measure of signal detection, which indicates the normalized rate of hits to false positives (d' = z(H) - z(F)). Increase in d' signifies improved signal detection, i.e. a better outcome. A d' near zero indicates a performance at chance, i.e., a poor performance.

Outcome measures

Measure	Right Active-tDCS n=14 Participants 2-3 times/week for 12 weeks: ramp-up for 30 seconds, 2mA right (AF4 anode - AF3 cathode) for 20 min, and then ramp-down for 30 seconds. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.	Left Active-tDCS n=10 Participants 2-3 times/week for 12 weeks: ramp-up for 30 seconds, 2mA left (AF3 anode - AF4 cathode) for 20 min, and then ramp-down for 30 seconds. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.	Sham tDCS n=15 Participants Current will be turned off immediately after the initial 30-second ramp-up period. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.
D-prime Score	3.22 arbitrary units Standard Deviation 0.88	3.37 arbitrary units Standard Deviation 0.75	3.18 arbitrary units Standard Deviation 1.27

PRIMARY outcome

Timeframe: mid-test (week 6)

The Dot Pattern Expectancy (DPX) task is an adaptation of the expectancy AX task that uses pairs of simple dot patterns rather than letter pairs as stimuli. The DPX task will be performed in 3 blocks. Each trial consists of a cue dot pattern followed by a probe dot pattern. Different combinations of cues and probes enable the identification of a specific deficit in a subject's ability to maintain goal-relevant information throughout a trial. Timing will be jittered and each block of the DPX task will consist of 40 trials: 24 AX (60%), 6 AY (15%), 6 BX (15%) and 4 BY (10%). Each block will last 6 minutes. d'-context will be calculated as a measure of signal detection, which indicates the normalized rate of AX hits to BX false positives (d' = z(H) - z(F)). Increase in d' -context signified improved signal detection, i.e. a better outcome. A d' near zero indicates a performance at chance, i.e., a poor performance.

Outcome measures

Measure	Right Active-tDCS n=16 Participants 2-3 times/week for 12 weeks: ramp-up for 30 seconds, 2mA right (AF4 anode - AF3 cathode) for 20 min, and then ramp-down for 30 seconds. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.	Left Active-tDCS n=10 Participants 2-3 times/week for 12 weeks: ramp-up for 30 seconds, 2mA left (AF3 anode - AF4 cathode) for 20 min, and then ramp-down for 30 seconds. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.	Sham tDCS n=17 Participants Current will be turned off immediately after the initial 30-second ramp-up period. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.
Changes in DPX Task Performance	2.90 arbitrary units Standard Deviation 1.02	3.71 arbitrary units Standard Deviation 0.45	2.84 arbitrary units Standard Deviation 1.04

PRIMARY outcome

Timeframe: post-test (week 12)

The Dot Pattern Expectancy (DPX) task is an adaptation of the expectancy AX task that uses pairs of simple dot patterns rather than letter pairs as stimuli. The DPX task will be performed in 3 blocks. Each trial consists of a cue dot pattern followed by a probe dot pattern. Different combinations of cues and probes enable the identification of a specific deficit in a subject's ability to maintain goal-relevant information throughout a trial. Timing will be jittered and each block of the DPX task will consist of 40 trials: 24 AX (60%), 6 AY (15%), 6 BX (15%) and 4 BY (10%). Each block will last 6 minutes. d'-context will be calculated as a measure of signal detection, which indicates the normalized rate of AX hits to BX false positives (d' = z(H) - z(F)). Increase in d' -context signified improved signal detection, i.e. a better outcome. A d' near zero indicates a performance at chance, i.e., a poor performance.

Outcome measures

Measure	Right Active-tDCS n=14 Participants 2-3 times/week for 12 weeks: ramp-up for 30 seconds, 2mA right (AF4 anode - AF3 cathode) for 20 min, and then ramp-down for 30 seconds. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.	Left Active-tDCS n=10 Participants 2-3 times/week for 12 weeks: ramp-up for 30 seconds, 2mA left (AF3 anode - AF4 cathode) for 20 min, and then ramp-down for 30 seconds. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.	Sham tDCS n=15 Participants Current will be turned off immediately after the initial 30-second ramp-up period. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.
Changes in DPX Task Performance	2.92 arbitrary units Standard Deviation 0.91	3.72 arbitrary units Standard Deviation 0.81	2.91 arbitrary units Standard Deviation 1.12

PRIMARY outcome

Timeframe: mid-test (week 6)

Intends to provide a relatively brief evaluation of key cognitive domains relevant to schizophrenia and related disorders. The composite score is reported as a T-score, with a mean of 50 and standard deviation of 10. Higher values indicate greater cognitive functioning.

Outcome measures

Measure	Right Active-tDCS n=17 Participants 2-3 times/week for 12 weeks: ramp-up for 30 seconds, 2mA right (AF4 anode - AF3 cathode) for 20 min, and then ramp-down for 30 seconds. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.	Left Active-tDCS n=10 Participants 2-3 times/week for 12 weeks: ramp-up for 30 seconds, 2mA left (AF3 anode - AF4 cathode) for 20 min, and then ramp-down for 30 seconds. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.	Sham tDCS n=18 Participants Current will be turned off immediately after the initial 30-second ramp-up period. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.
Changes in Measurement and Treatment Research to Improve Cognition in Schizophrenia (MATRICS) Consensus Cognitive Battery (MCCB) Composite Score	57.9 T-score Standard Deviation 9.9	57.8 T-score Standard Deviation 8.04	56.1 T-score Standard Deviation 10.8

PRIMARY outcome

Timeframe: post-test (week 12)

Intends to provide a relatively brief evaluation of key cognitive domains relevant to schizophrenia and related disorders. The composite score is reported as a T-score, with a mean of 50 and standard deviation of 10. Higher values indicate greater cognitive functioning.

Outcome measures

Measure	Right Active-tDCS n=15 Participants 2-3 times/week for 12 weeks: ramp-up for 30 seconds, 2mA right (AF4 anode - AF3 cathode) for 20 min, and then ramp-down for 30 seconds. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.	Left Active-tDCS n=9 Participants 2-3 times/week for 12 weeks: ramp-up for 30 seconds, 2mA left (AF3 anode - AF4 cathode) for 20 min, and then ramp-down for 30 seconds. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.	Sham tDCS n=15 Participants Current will be turned off immediately after the initial 30-second ramp-up period. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.
Changes in Measurement and Treatment Research to Improve Cognition in Schizophrenia (MATRICS) Consensus Cognitive Battery (MCCB) Composite Score	59.1 T-score Standard Deviation 9.7	62.2 T-score Standard Deviation 6.22	60.2 T-score Standard Deviation 11.2

PRIMARY outcome

Timeframe: follow up (week 24)

Intends to provide a relatively brief evaluation of key cognitive domains relevant to schizophrenia and related disorders. The composite score is reported as a T-score, with a mean of 50 and standard deviation of 10. Higher values indicate greater cognitive functioning.

Outcome measures

Measure	Right Active-tDCS n=13 Participants 2-3 times/week for 12 weeks: ramp-up for 30 seconds, 2mA right (AF4 anode - AF3 cathode) for 20 min, and then ramp-down for 30 seconds. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.	Left Active-tDCS n=9 Participants 2-3 times/week for 12 weeks: ramp-up for 30 seconds, 2mA left (AF3 anode - AF4 cathode) for 20 min, and then ramp-down for 30 seconds. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.	Sham tDCS n=15 Participants Current will be turned off immediately after the initial 30-second ramp-up period. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.
Changes in Measurement and Treatment Research to Improve Cognition in Schizophrenia (MATRICS) Consensus Cognitive Battery (MCCB) Composite Score	60.8 T-score Standard Deviation 6.6	61.1 T-score Standard Deviation 8.2	63.3 T-score Standard Deviation 8.1

PRIMARY outcome

Timeframe: mid-test (week 6)

Task-dependent thalamocortical connectivity associated with the Dot Pattern Expectancy (DPX) task demands will be identified by analyzing cue and probe events together with the thalamic regressor using psychophysiological interaction analysis (PPI). The thalamic regressor is the time series of the mediodorsal thalamus from the Melbourne atlas. We examined B-cue related connectivity. The PPI analysis calculates the functional connectivity between the mediodorsal thalamus and all other brain regions specifically during B-cue trials. Neural activation related to the thalamic regressor was compared to neural activation during the fixation (no choices made) to normalize the relative activation (z-score). Positive values indicate increased functional connectivity with the thalamus during the B-cue responses. A z-score of zero represents no difference compared to the fixation cross (no choices). We report the average z-score of the PPI regressor within the control network (Yeo et al., 2011).

Outcome measures

Measure	Right Active-tDCS n=15 Participants 2-3 times/week for 12 weeks: ramp-up for 30 seconds, 2mA right (AF4 anode - AF3 cathode) for 20 min, and then ramp-down for 30 seconds. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.	Left Active-tDCS n=10 Participants 2-3 times/week for 12 weeks: ramp-up for 30 seconds, 2mA left (AF3 anode - AF4 cathode) for 20 min, and then ramp-down for 30 seconds. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.	Sham tDCS n=17 Participants Current will be turned off immediately after the initial 30-second ramp-up period. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.
Changes in Task-dependent Thalamocortical Functional Connectivity (fMRI) During the DPX Task.	-0.25 z-score Standard Deviation 0.42	-0.09 z-score Standard Deviation 0.57	-0.44 z-score Standard Deviation 0.29

PRIMARY outcome

Timeframe: post-test (week 12)

Task-dependent thalamocortical connectivity associated with the Dot Pattern Expectancy (DPX) task demands will be identified by analyzing cue and probe events together with the thalamic regressor using psychophysiological interaction analysis (PPI). The thalamic regressor is the time series of the mediodorsal thalamus from the Melbourne atlas. We examined B-cue related connectivity. The PPI analysis calculates the functional connectivity between the mediodorsal thalamus and all other brain regions specifically during B-cue trials. Neural activation related to the thalamic regressor was compared to neural activation during the fixation (no choices made) to normalize the relative activation (z-score). Positive values indicate increased functional connectivity with the thalamus during the B-cue responses. A z-score of zero represents no difference compared to the fixation cross (no choices). We report the average z-score of the PPI regressor within the control network (Yeo et al., 2011).

Outcome measures

Measure	Right Active-tDCS n=14 Participants 2-3 times/week for 12 weeks: ramp-up for 30 seconds, 2mA right (AF4 anode - AF3 cathode) for 20 min, and then ramp-down for 30 seconds. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.	Left Active-tDCS n=10 Participants 2-3 times/week for 12 weeks: ramp-up for 30 seconds, 2mA left (AF3 anode - AF4 cathode) for 20 min, and then ramp-down for 30 seconds. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.	Sham tDCS n=15 Participants Current will be turned off immediately after the initial 30-second ramp-up period. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.
Changes in Task-dependent Thalamocortical Functional Connectivity (fMRI) During the DPX Task.	-0.16 z-score Standard Deviation 0.52	-0.25 z-score Standard Deviation 0.36	-0.25 z-score Standard Deviation 0.24

Adverse Events

Right Active-tDCS

Serious events: 0 serious events

Other events: 2 other events

Deaths: 2 deaths

Left Active-tDCS

Serious events: 0 serious events

Other events: 0 other events

Deaths: 0 deaths

Sham tDCS

Serious events: 0 serious events

Other events: 0 other events

Deaths: 0 deaths

Serious adverse events

Adverse event data not reported

Other adverse events

Measure	Right Active-tDCS n=20 participants at risk 2-3 times/week for 12 weeks: ramp-up for 30 seconds, 2mA right (AF4 anode - AF3 cathode) for 20 min, and then ramp-down for 30 seconds. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.	Left Active-tDCS n=18 participants at risk 2-3 times/week for 12 weeks: ramp-up for 30 seconds, 2mA left (AF3 anode - AF4 cathode) for 20 min, and then ramp-down for 30 seconds. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.	Sham tDCS n=20 participants at risk Current will be turned off immediately after the initial 30-second ramp-up period. Transcranial direct current stimulation (tDCS): Three different stimulation montages will be programmed: right, left and sham. During the Ramp periods, 2 mA current will be delivered to both AF3 and AF4 with an ascending (RampUp) and descending ramp (RampDown) over 30 sec via two saline soaked electrode sponges (\~ 25cm²; current density = 0.08 mA/cm²). In this way, all subjects experience the same sensation on both sides to blind them to condition. During the Constant period, current will be set based on the Condition: Right - 2mA AF4 anode-AF3 cathode; Left - 2mA applied to AF3 anode-AF4 cathode; Sham - current turned off.
General disorders Temporary moderate/severe tDCS headband discomfort	10.0% 2/20 • Number of events 2 • 12 weeks assessed adverse events during the 12 weeks that individuals completed tDCS. They were asked after each session if they had an adverse reaction during the tDCS session.	0.00% 0/18 • 12 weeks assessed adverse events during the 12 weeks that individuals completed tDCS. They were asked after each session if they had an adverse reaction during the tDCS session.	0.00% 0/20 • 12 weeks assessed adverse events during the 12 weeks that individuals completed tDCS. They were asked after each session if they had an adverse reaction during the tDCS session.

Additional Information

Rebecca Kazinka

University of Minnesota

Phone: 612-626-6772

Email: kazin003@umn.edu

Results disclosure agreements

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