Trial Outcomes & Findings for Cognitive Recovery With Cannabis Abstinence Among High School-Aged Adolescents (NCT NCT03276221)

NCT ID: NCT03276221

Last Updated: 2024-02-01

Results Overview

The total number of words a subject correctly identified as either previously studied or novel during the immediate recognition phase. This is a specific measure from the Verbal Recognition Memory (VRM) Module, which is part of the Cambridge Neuropsychological Test Automated Battery (CANTAB). The VRM module assesses verbal memory and new learning. Count variable, ranging from 0 to 36, with higher scores indicating better recognition memory performance.

• Recruitment status: COMPLETED
• Study phase: NA
• Target enrollment: 201 participants
• Primary outcome timeframe: 1, 2, 3, and 4 Weeks
• Results posted on: 2024-02-01

Participant Flow

Recruitment was conducted from 2017 to 2022.

Participant milestones

Measure	Abstinent This group of cannabis users agreed to remain abstinent from cannabis use for 30 days. Abstinence: Cannabis users randomized to this condition will be enrolled in a contingency management intervention for 30 days of cannabis abstinence.	Monitoring This group of cannabis users were not asked to change their cannabis use behavior.	Non-Users This is a group of adolescents with little to no cannabis use history and were non-randomized.
Overall Study STARTED	64	68	69
Overall Study COMPLETED	54	66	69
Overall Study NOT COMPLETED	10	2	0

Reasons for withdrawal

Measure	Abstinent This group of cannabis users agreed to remain abstinent from cannabis use for 30 days. Abstinence: Cannabis users randomized to this condition will be enrolled in a contingency management intervention for 30 days of cannabis abstinence.	Monitoring This group of cannabis users were not asked to change their cannabis use behavior.	Non-Users This is a group of adolescents with little to no cannabis use history and were non-randomized.
Overall Study Lost to Follow-up	6	2	0
Overall Study Did not abstain from cannabis as per protocol	4	0	0

Baseline Characteristics

Cognitive Recovery With Cannabis Abstinence Among High School-Aged Adolescents

Baseline characteristics by cohort

Measure	Abstinent n=54 Participants This group of cannabis users are agree to remain abstinent from cannabis use for 30 days. Abstinence: Cannabis users randomized to this condition will be enrolled in a contingency management intervention for 30 days of cannabis abstinence.	Monitoring n=66 Participants This group of cannabis users are not asked to change their cannabis use behavior.	Non-Users n=69 Participants This is a group of adolescents with little to no cannabis use history and is non-randomized.	Total n=189 Participants Total of all reporting groups
Age, Continuous	18.3 years STANDARD_DEVIATION 1.4 • n=5 Participants	18.1 years STANDARD_DEVIATION 1.5 • n=7 Participants	17.0 years STANDARD_DEVIATION 1.8 • n=5 Participants	17.8 years STANDARD_DEVIATION 1.7 • n=4 Participants
Sex: Female, Male Female	26 Participants n=5 Participants	31 Participants n=7 Participants	40 Participants n=5 Participants	97 Participants n=4 Participants
Sex: Female, Male Male	28 Participants n=5 Participants	35 Participants n=7 Participants	29 Participants n=5 Participants	92 Participants n=4 Participants
Ethnicity (NIH/OMB) Hispanic or Latino	5 Participants n=5 Participants	16 Participants n=7 Participants	9 Participants n=5 Participants	30 Participants n=4 Participants
Ethnicity (NIH/OMB) Not Hispanic or Latino	49 Participants n=5 Participants	50 Participants n=7 Participants	60 Participants n=5 Participants	159 Participants n=4 Participants
Ethnicity (NIH/OMB) Unknown or Not Reported	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants
Race (NIH/OMB) American Indian or Alaska Native	1 Participants n=5 Participants	1 Participants n=7 Participants	0 Participants n=5 Participants	2 Participants n=4 Participants
Race (NIH/OMB) Asian	4 Participants n=5 Participants	7 Participants n=7 Participants	6 Participants n=5 Participants	17 Participants n=4 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
Race (NIH/OMB) Black or African American	10 Participants n=5 Participants	10 Participants n=7 Participants	14 Participants n=5 Participants	34 Participants n=4 Participants
Race (NIH/OMB) White	31 Participants n=5 Participants	34 Participants n=7 Participants	39 Participants n=5 Participants	104 Participants n=4 Participants
Race (NIH/OMB) More than one race	6 Participants n=5 Participants	11 Participants n=7 Participants	4 Participants n=5 Participants	21 Participants n=4 Participants
Race (NIH/OMB) Unknown or Not Reported	2 Participants n=5 Participants	3 Participants n=7 Participants	6 Participants n=5 Participants	11 Participants n=4 Participants
Region of Enrollment United States	54 participants n=5 Participants	66 participants n=7 Participants	69 participants n=5 Participants	189 participants n=4 Participants
APSS	0.1 Score on a scale STANDARD_DEVIATION 0.6 • n=5 Participants	0.3 Score on a scale STANDARD_DEVIATION 0.8 • n=7 Participants	0.1 Score on a scale STANDARD_DEVIATION 0.5 • n=5 Participants	0.2 Score on a scale STANDARD_DEVIATION 0.7 • n=4 Participants
PQB	2.9 Score on a scale STANDARD_DEVIATION 3.7 • n=5 Participants	3.8 Score on a scale STANDARD_DEVIATION 3.8 • n=7 Participants	1.8 Score on a scale STANDARD_DEVIATION 2.3 • n=5 Participants	2.8 Score on a scale STANDARD_DEVIATION 3.4 • n=4 Participants
Years Spent Using Cannabis	3.3 years STANDARD_DEVIATION 1.3 • n=5 Participants	3.4 years STANDARD_DEVIATION 1.5 • n=7 Participants	0 years STANDARD_DEVIATION 0 • n=5 Participants	3.4 years STANDARD_DEVIATION 1.4 • n=4 Participants
Days Per Month Spent Using Cannabis	3.6 days STANDARD_DEVIATION 2.8 • n=5 Participants	3.3 days STANDARD_DEVIATION 2.6 • n=7 Participants	0 days STANDARD_DEVIATION 0 • n=5 Participants	3.5 days STANDARD_DEVIATION 2.7 • n=4 Participants
THC-COOH	211.8 ng/mL STANDARD_DEVIATION 338 • n=5 Participants	389.6 ng/mL STANDARD_DEVIATION 745 • n=7 Participants	0 ng/mL STANDARD_DEVIATION 0 • n=5 Participants	306.3 ng/mL STANDARD_DEVIATION 594.6 • n=4 Participants
CUDIT-R	13.7 Score on a scale STANDARD_DEVIATION 5.4 • n=5 Participants	14.1 Score on a scale STANDARD_DEVIATION 5.5 • n=7 Participants	0 Score on a scale STANDARD_DEVIATION 0 • n=5 Participants	13.9 Score on a scale STANDARD_DEVIATION 5.4 • n=4 Participants
Days Per Month Spent Drinking Alcohol	0.7 days STANDARD_DEVIATION 0.8 • n=5 Participants	0.4 days STANDARD_DEVIATION 0.8 • n=7 Participants	0.1 days STANDARD_DEVIATION 0.2 • n=5 Participants	0.4 days STANDARD_DEVIATION 0.7 • n=4 Participants
AUDIT	5.4 Score on a scale STANDARD_DEVIATION 4.8 • n=5 Participants	5.9 Score on a scale STANDARD_DEVIATION 5.0 • n=7 Participants	1.9 Score on a scale STANDARD_DEVIATION 2.5 • n=5 Participants	4.3 Score on a scale STANDARD_DEVIATION 4.6 • n=4 Participants

PRIMARY outcome

Timeframe: 1, 2, 3, and 4 Weeks

Population: Pre-specified confirmatory analyses assessed differences between the abstinent and monitoring arms only (see attached Statistical Plan).

The number of times the subject chose the incorrect box for a stimulus on assessment problems plus an adjustment for the estimated number of errors they would have made on any problems/attempts/recalls they did not reach. This is a specific measure from the Paired Associates Learning (PAL) module, which is part of the Cambridge Neuropsychological Test Automated Battery (CANTAB). The PAL module assesses visual memory and new learning. Count variable, ranging from 0 to 70, where higher scores indicate more errors and worse performance.

Outcome measures

Measure	Abstinent n=54 Participants This group of cannabis users are agree to remain abstinent from cannabis use for 30 days. Abstinence: Cannabis users randomized to this condition will be enrolled in a contingency management intervention for 30 days of cannabis abstinence.	Monitoring n=66 Participants This group of cannabis users are not asked to change their cannabis use behavior.	Non-Users n=69 Participants This is a group of adolescents with little to no cannabis use history and were non-randomized.
Mean Difference in the Total Number of Errors From Paired Associates Learning (PAL) Module Averaged Over Weeks 1, 2, 3, and 4	5.6 score on a scale Standard Deviation 6.4	6.2 score on a scale Standard Deviation 7.7	5.9 score on a scale Standard Deviation 8.1

PRIMARY outcome

Timeframe: 1, 2, 3, and 4 Weeks

Population: Pre-specified confirmatory analyses assessed differences between the abstinent and monitoring arms only (see attached Statistical Analysis Plan).

The number of times a subject chose the correct box on their first attempt when recalling pattern locations, which was calculated across all trials. This is a specific measure from the Paired Associates Learning (PAL) module, which is part of the Cambridge Neuropsychological Test Automated Battery (CANTAB). The PAL module assesses visual memory and new learning. Count variable, ranging from 0 to 20, where higher scores indicate better memory performance.

Outcome measures

Measure	Abstinent n=54 Participants This group of cannabis users are agree to remain abstinent from cannabis use for 30 days. Abstinence: Cannabis users randomized to this condition will be enrolled in a contingency management intervention for 30 days of cannabis abstinence.	Monitoring n=66 Participants This group of cannabis users are not asked to change their cannabis use behavior.	Non-Users n=69 Participants This is a group of adolescents with little to no cannabis use history and were non-randomized.
Mean Difference in First Attempt Memory Score From Paired Associates Learning (PAL) Module Averaged Over Weeks 1, 2, 3, and 4	16.2 score on a scale Standard Deviation 3.2	15.8 score on a scale Standard Deviation 3.4	16.1 score on a scale Standard Deviation 3.6

PRIMARY outcome

Timeframe: 1, 2, 3, and 4 Weeks

Population: Pre-specified confirmatory analyses assessed differences between the abstinent and monitoring arms only (see attached Statistical Analysis Plan).

The longest length of sequences (spans) a subject successfully remembered in the original order. This is a specific measure from the Spatial Span (SSP) Module, which is part of the Cambridge Neuropsychological Test Automated Battery (CANTAB). The SSP assesses visuospatial working memory capacity. Count variable, ranging from 2 to 9, with higher scores indicating better memory performance.

Outcome measures

Measure	Abstinent n=54 Participants This group of cannabis users are agree to remain abstinent from cannabis use for 30 days. Abstinence: Cannabis users randomized to this condition will be enrolled in a contingency management intervention for 30 days of cannabis abstinence.	Monitoring n=66 Participants This group of cannabis users are not asked to change their cannabis use behavior.	Non-Users n=69 Participants This is a group of adolescents with little to no cannabis use history and were non-randomized.
Mean Difference in Forward Span Length From Spatial Span (SSP) Module Averaged Over Weeks 1, 2, 3, and 4	7.6 score on a scale Standard Deviation 1.3	7.4 score on a scale Standard Deviation 1.3	7.6 score on a scale Standard Deviation 1.4

PRIMARY outcome

Timeframe: 1, 2, 3, and 4 Weeks

Population: Pre-specified confirmatory analyses assessed differences between the abstinent and monitoring arms only (see attached Statistical Analysis Plan).

The longest length of sequences (spans) a subject successfully remembered in the reverse order. This is a specific measure from the Spatial Span (SSP) Module, which is part of the Cambridge Neuropsychological Test Automated Battery (CANTAB). The SSP assesses visuospatial working memory capacity. Count variable, ranging from 2 to 9, with higher scores indicating better memory performance.

Outcome measures

Measure	Abstinent n=54 Participants This group of cannabis users are agree to remain abstinent from cannabis use for 30 days. Abstinence: Cannabis users randomized to this condition will be enrolled in a contingency management intervention for 30 days of cannabis abstinence.	Monitoring n=66 Participants This group of cannabis users are not asked to change their cannabis use behavior.	Non-Users n=69 Participants This is a group of adolescents with little to no cannabis use history and were non-randomized.
Mean Difference in Reverse Span Length From Spatial Span (SSP) Module Averaged Over Weeks 1, 2, 3, and 4	6.9 score on a scale Standard Deviation 1.4	7 score on a scale Standard Deviation 1.5	6.9 score on a scale Standard Deviation 1.6

PRIMARY outcome

Timeframe: 1, 2, 3, and 4 Weeks

Population: Pre-specified confirmatory analyses assessed differences between the abstinent and monitoring arms only (see attached Statistical Analysis Plan).

The total number of distinct words a subject correctly recalled from the studied list of 18 words during the immediate free recall phase. This is a specific measure from the Verbal Recognition Memory (VRM) Module, which is part of the Cambridge Neuropsychological Test Automated Battery (CANTAB). The VRM module assesses verbal memory and new learning. Count variable, ranging from 0 to 18, with higher scores indicating better immediate recall performance.

Outcome measures

Measure	Abstinent n=54 Participants This group of cannabis users are agree to remain abstinent from cannabis use for 30 days. Abstinence: Cannabis users randomized to this condition will be enrolled in a contingency management intervention for 30 days of cannabis abstinence.	Monitoring n=66 Participants This group of cannabis users are not asked to change their cannabis use behavior.	Non-Users n=69 Participants This is a group of adolescents with little to no cannabis use history and were non-randomized.
Mean Difference in the Total Number Correct in the Immediate Recall Measure From the Verbal Recognition Memory (VRM) Module Averaged Over Weeks 1, 2, 3, and 4	7.3 score on a scale Standard Deviation 2.3	7.3 score on a scale Standard Deviation 2.5	7.7 score on a scale Standard Deviation 2.7

PRIMARY outcome

Timeframe: 1, 2, 3, and 4 Weeks

Population: Pre-specified confirmatory analyses assessed differences between the abstinent and monitoring arms only (see attached Statistical Analysis Plan).

The total number of distinct words a subject correctly recalled from the studied list of 18 words during the delayed free recall phase. This is a specific measure from the Verbal Recognition Memory (VRM) Module, which is part of the Cambridge Neuropsychological Test Automated Battery (CANTAB). The VRM module assesses verbal memory and new learning. Count variable, ranging from 0 to 18, with higher scores indicating better immediate recall performance.

Outcome measures

Measure	Abstinent n=54 Participants This group of cannabis users are agree to remain abstinent from cannabis use for 30 days. Abstinence: Cannabis users randomized to this condition will be enrolled in a contingency management intervention for 30 days of cannabis abstinence.	Monitoring n=66 Participants This group of cannabis users are not asked to change their cannabis use behavior.	Non-Users n=69 Participants This is a group of adolescents with little to no cannabis use history and were non-randomized.
Mean Difference in the Total Number Correct in the Delayed Recall Measure From the Verbal Recognition Memory (VRM) Module Averaged Over Weeks 1, 2, 3, and 4	6.5 score on a scale Standard Deviation 2.8	6.5 score on a scale Standard Deviation 3	7.2 score on a scale Standard Deviation 3.1

PRIMARY outcome

Timeframe: 1, 2, 3, and 4 Weeks

Population: Pre-specified confirmatory analyses assessed differences between the abstinent and monitoring arms only (see attached Statistical Analysis Plan).

The total number of words a subject correctly identified as either previously studied or novel during the immediate recognition phase. This is a specific measure from the Verbal Recognition Memory (VRM) Module, which is part of the Cambridge Neuropsychological Test Automated Battery (CANTAB). The VRM module assesses verbal memory and new learning. Count variable, ranging from 0 to 36, with higher scores indicating better recognition memory performance.

Outcome measures

Measure	Abstinent n=54 Participants This group of cannabis users are agree to remain abstinent from cannabis use for 30 days. Abstinence: Cannabis users randomized to this condition will be enrolled in a contingency management intervention for 30 days of cannabis abstinence.	Monitoring n=66 Participants This group of cannabis users are not asked to change their cannabis use behavior.	Non-Users n=69 Participants This is a group of adolescents with little to no cannabis use history and were non-randomized.
Mean Difference in the Total Number Correct in the Immediate Recognition Condition From the Verbal Recognition Memory (VRM) Module Averaged Over Weeks 1, 2, 3, and 4	32.3 score on a scale Standard Deviation 2.1	32.4 score on a scale Standard Deviation 2.9	31.9 score on a scale Standard Deviation 3.1

PRIMARY outcome

Timeframe: 1, 2, 3, and 4 Weeks

Population: Pre-specified confirmatory analyses assessed differences between the abstinent and monitoring arms only (see attached Statistical Analysis Plan).

The total number of words a subject correctly identified as either previously studied or novel during the delayed recognition phase. This is a specific measure from the Verbal Recognition Memory (VRM) Module, which is part of the Cambridge Neuropsychological Test Automated Battery (CANTAB). The VRM module assesses verbal memory and new learning. Count variable, ranging from 0 to 36, with higher scores indicating better recognition memory performance.

Outcome measures

Measure	Abstinent n=54 Participants This group of cannabis users are agree to remain abstinent from cannabis use for 30 days. Abstinence: Cannabis users randomized to this condition will be enrolled in a contingency management intervention for 30 days of cannabis abstinence.	Monitoring n=66 Participants This group of cannabis users are not asked to change their cannabis use behavior.	Non-Users n=69 Participants This is a group of adolescents with little to no cannabis use history and were non-randomized.
Mean Difference in the Total Number Correct in the Delayed Recognition Condition From the Verbal Recognition Memory (VRM) Module Averaged Over Weeks 1, 2, 3, and 4	30.5 score on a scale Standard Deviation 3	30.9 score on a scale Standard Deviation 3.6	30.3 score on a scale Standard Deviation 4

PRIMARY outcome

Timeframe: 1, 2, 3, and 4 Weeks

Population: Pre-specified confirmatory analyses assessed differences between the abstinent and monitoring arms only (see attached Statistical Analysis Plan).

The total number of words a subject correctly identified as either previously studied or novel during the delayed recognition phase. This is a specific measure from the Multitasking Test (MTT) module, which is part of the Cambridge Neuropsychological Test Automated Battery (CANTAB). The MTT assesses the participant's ability to manage conflicting information provided by the direction of an arrow and its location on the screen and to ignore task-irrelevant information. Count variable, ranging from 0 to 160, with higher scores indicating more errors and worse performance.

Outcome measures

Measure	Abstinent n=54 Participants This group of cannabis users are agree to remain abstinent from cannabis use for 30 days. Abstinence: Cannabis users randomized to this condition will be enrolled in a contingency management intervention for 30 days of cannabis abstinence.	Monitoring n=66 Participants This group of cannabis users are not asked to change their cannabis use behavior.	Non-Users n=69 Participants This is a group of adolescents with little to no cannabis use history and were non-randomized.
Mean Difference in the Total Number Incorrect From the Multitasking Test (MTT) Module Averaged Over Weeks 1, 2, 3, and 4	7.1 score on a scale Standard Deviation 5.6	8.5 score on a scale Standard Deviation 7.7	9.1 score on a scale Standard Deviation 8.1

PRIMARY outcome

Timeframe: 1, 2, 3, and 4 Weeks

Population: Pre-specified confirmatory analyses assessed differences between the abstinent and monitoring arms only (see attached Statistical Analysis Plan).

The response latency for each participant was defined as a summary (median) computed over their response times for all correct responses irrespective of condition. This is a specific measure from the Multitasking Test (MTT) module, which is part of the Cambridge Neuropsychological Test Automated Battery (CANTAB). The MTT assesses the participant's ability to manage conflicting information provided by the direction of an arrow and its location on the screen and to ignore task-irrelevant information. Response time variable in milliseconds (ms), ranging from 100 to 2000 ms, with higher values indicating slower performance across all trials.

Outcome measures

Measure	Abstinent n=54 Participants This group of cannabis users are agree to remain abstinent from cannabis use for 30 days. Abstinence: Cannabis users randomized to this condition will be enrolled in a contingency management intervention for 30 days of cannabis abstinence.	Monitoring n=66 Participants This group of cannabis users are not asked to change their cannabis use behavior.	Non-Users n=69 Participants This is a group of adolescents with little to no cannabis use history and were non-randomized.
Mean Difference in the Response Latency From the Multitasking Test (MTT) Module Averaged Over Weeks 1, 2, 3, and 4	474 score on a scale Standard Deviation 72	468 score on a scale Standard Deviation 78	482 score on a scale Standard Deviation 86

PRIMARY outcome

Timeframe: 1, 2, 3, and 4 Weeks

Population: Pre-specified confirmatory analyses assessed differences between the abstinent and monitoring arms only (see attached Statistical Analysis Plan).

The incongruency cost for each participant was defined as a summary (median) of response times for incongruent trials minus a summary (median) of response times for congruent trials. This is a specific measure from the Multitasking Test (MTT) module, which is part of the Cambridge Neuropsychological Test Automated Battery (CANTAB). The MTT assesses the participant's ability to manage conflicting information provided by the direction of an arrow and its location on the screen and to ignore task-irrelevant information. Difference score in milliseconds (ms), ranging from -1900 to 1900 ms, with higher values indicating slower responses on incongruent trials, suggesting that it takes longer to process conflicting information.

Outcome measures

Measure	Abstinent n=54 Participants This group of cannabis users are agree to remain abstinent from cannabis use for 30 days. Abstinence: Cannabis users randomized to this condition will be enrolled in a contingency management intervention for 30 days of cannabis abstinence.	Monitoring n=66 Participants This group of cannabis users are not asked to change their cannabis use behavior.	Non-Users n=69 Participants This is a group of adolescents with little to no cannabis use history and were non-randomized.
Mean Difference in the Incongruency Cost From the Multitasking Test (MTT) Module Averaged Over Weeks 1, 2, 3, and 4	37 score on a scale Standard Deviation 33	40 score on a scale Standard Deviation 32	43 score on a scale Standard Deviation 37

PRIMARY outcome

Timeframe: 1, 2, 3, and 4 Weeks

Population: Pre-specified confirmatory analyses assessed differences between the abstinent and monitoring arms only (see attached Statistical Analysis Plan).

The multitasking cost for each participant was defined as a summary (median) of response times for the multi-task blocks (trials alternated between having to respond to the direction or position of the arrow) minus a summary (median) of response times for the single-task blocks (all trials consisted of either responding to the direction or position of the arrow). This is a specific measure from the Multitasking Test (MTT) module, which is part of the Cambridge Neuropsychological Test Automated Battery (CANTAB). The MTT assesses the participant's ability to manage conflicting information provided by the direction of an arrow and its location on the screen and to ignore task-irrelevant information. Difference score in milliseconds (ms), ranging from -1900 to 1900 ms, with higher values indicating slower responses on multi-task blocks, suggesting that it takes longer to process multiple sources of information.

Outcome measures

Measure	Abstinent n=54 Participants This group of cannabis users are agree to remain abstinent from cannabis use for 30 days. Abstinence: Cannabis users randomized to this condition will be enrolled in a contingency management intervention for 30 days of cannabis abstinence.	Monitoring n=66 Participants This group of cannabis users are not asked to change their cannabis use behavior.	Non-Users n=69 Participants This is a group of adolescents with little to no cannabis use history and were non-randomized.
Mean Difference in the Multitasking Cost From the Multitasking Test (MTT) Module Averaged Over Weeks 1, 2, 3, and 4	96 score on a scale Standard Deviation 71	71 score on a scale Standard Deviation 68	81 score on a scale Standard Deviation 81

PRIMARY outcome

Timeframe: 1, 2, 3, and 4 Weeks

Population: Pre-specified confirmatory analyses assessed differences between the abstinent and monitoring arms only (see attached Statistical Analysis Plan).

The total number of trials where the subject chose the correct answer on the first attempt. This is a specific measure from the One Touch Stockings of Cambridge (OTS) Module, which is part of the Cambridge Neuropsychological Test Automated Battery (CANTAB). The OTS module assesses executive function based upon the Tower of Hanoi test. Count variable, ranging from 0 to 15, with higher scores indicating better performance.

Outcome measures

Measure	Abstinent n=54 Participants This group of cannabis users are agree to remain abstinent from cannabis use for 30 days. Abstinence: Cannabis users randomized to this condition will be enrolled in a contingency management intervention for 30 days of cannabis abstinence.	Monitoring n=66 Participants This group of cannabis users are not asked to change their cannabis use behavior.	Non-Users n=69 Participants This is a group of adolescents with little to no cannabis use history and were non-randomized.
Mean Difference in Number of Problems Correctly Solved on the First Choice From the One Touch Stockings of Cambridge (OTS) Module Averaged Over Weeks 1, 2, 3, and 4	12.2 score on a scale Standard Deviation 1.8	11.5 score on a scale Standard Deviation 2.3	11.5 score on a scale Standard Deviation 2.7

PRIMARY outcome

Timeframe: 1, 2, 3, and 4 Weeks

Population: Pre-specified confirmatory analyses assessed differences between the abstinent and monitoring arms only (see attached Statistical Analysis Plan).

The latency to first correct choice for each participant was defined as a summary (median) of the response times for all trials in which the subject picked the correct choice on the first attempt. This is a specific measure from the One Touch Stockings of Cambridge (OTS) Module, which is part of the Cambridge Neuropsychological Test Automated Battery (CANTAB). The OTS module assesses executive function based upon the Tower of Hanoi test. Response time variable in milliseconds (ms), a positive unbounded variable, with higher values indicating slower performance across correct trials.

Outcome measures

Measure	Abstinent n=54 Participants This group of cannabis users are agree to remain abstinent from cannabis use for 30 days. Abstinence: Cannabis users randomized to this condition will be enrolled in a contingency management intervention for 30 days of cannabis abstinence.	Monitoring n=66 Participants This group of cannabis users are not asked to change their cannabis use behavior.	Non-Users n=69 Participants This is a group of adolescents with little to no cannabis use history and were non-randomized.
Mean Difference in the Latency to First Correct Choice From the One Touch Stockings of Cambridge (OTS) Module Averaged Over Weeks 1, 2, 3, and 4	7036 score on a scale Standard Deviation 2794	6690 score on a scale Standard Deviation 2283	6851 score on a scale Standard Deviation 3183

PRIMARY outcome

Timeframe: 1, 2, 3, and 4 Weeks

Population: Pre-specified confirmatory analyses assessed differences between the abstinent and monitoring arms only (see attached Statistical Analysis Plan).

The estimate of the duration at which a person can successfully inhibit a response 50% of the time, represents the time before which all actions become ballistic and a subject is unable to cancel a response selection. This is a specific measure from the Stop Signal Task (SST) Module, which is part of the Cambridge Neuropsychological Test Automated Battery (CANTAB). The SST module assesses response inhibition (impulse control). Response time variable in milliseconds (ms), ranging from 0 to 500 ms, with higher values indicating that it takes longer for a person to inhibit a response.

Outcome measures

Measure	Abstinent n=54 Participants This group of cannabis users are agree to remain abstinent from cannabis use for 30 days. Abstinence: Cannabis users randomized to this condition will be enrolled in a contingency management intervention for 30 days of cannabis abstinence.	Monitoring n=66 Participants This group of cannabis users are not asked to change their cannabis use behavior.	Non-Users n=69 Participants This is a group of adolescents with little to no cannabis use history and were non-randomized.
Mean Difference in Stop Signal Reaction Time From Stop Signal Task (SST) Module Averaged Over Weeks 1, 2, 3, and 4	210 score on a scale Standard Deviation 35	219 score on a scale Standard Deviation 49	222 score on a scale Standard Deviation 56

PRIMARY outcome

Timeframe: 1, 2, 3, and 4 Weeks

Population: Pre-specified confirmatory analyses assessed differences between the abstinent and monitoring arms only (see attached Statistical Analysis Plan).

The number of times a subject incorrectly revisited a box that had contained a token in a previous trial across the 4, 6, and 8 box conditions. This is a specific measure from the Spatial Working Memory (SWM) module, which is part of the Cambridge Neuropsychological Test Automated Battery (CANTAB). The SWM module provides a measure of strategy as well as working memory errors. Count variable, ranging from 0 to 63, with higher scores indicating worse performance.

Outcome measures

Measure	Abstinent n=54 Participants This group of cannabis users are agree to remain abstinent from cannabis use for 30 days. Abstinence: Cannabis users randomized to this condition will be enrolled in a contingency management intervention for 30 days of cannabis abstinence.	Monitoring n=66 Participants This group of cannabis users are not asked to change their cannabis use behavior.	Non-Users n=69 Participants This is a group of adolescents with little to no cannabis use history and were non-randomized.
Mean Difference in the Total Number of Between Errors From the Spatial Working Memory (SWM) Module Averaged Over Weeks 1, 2, 3, and 4	3.6 score on a scale Standard Deviation 5.4	4.6 score on a scale Standard Deviation 6.3	5.5 score on a scale Standard Deviation 7.7

PRIMARY outcome

Timeframe: 1, 2, 3, and 4 Weeks

Population: Pre-specified confirmatory analyses assessed differences between the abstinent and monitoring arms only (see attached Statistical Analysis Plan).

The number of times subjects began a new search from the same box they started on in previous trials. It is assumed that a person who begins from the same box each time is using a planned strategy to find the tokens. This is a specific measure from the Spatial Working Memory (SWM) module, which is part of the Cambridge Neuropsychological Test Automated Battery (CANTAB). The SWM module provides a measure of strategy as well as working memory errors. Count variable, ranging from 2 to 14, with higher scores indicating low strategy, meaning a subject began searches from many different boxes.

Outcome measures

Measure	Abstinent n=54 Participants This group of cannabis users are agree to remain abstinent from cannabis use for 30 days. Abstinence: Cannabis users randomized to this condition will be enrolled in a contingency management intervention for 30 days of cannabis abstinence.	Monitoring n=66 Participants This group of cannabis users are not asked to change their cannabis use behavior.	Non-Users n=69 Participants This is a group of adolescents with little to no cannabis use history and were non-randomized.
Mean Difference in the Participant's Strategy for 6-8 Box Conditions From the Spatial Working Memory (SWM) Module Averaged Over Weeks 1, 2, 3, and 4	5.4 score on a scale Standard Deviation 2.6	5.7 score on a scale Standard Deviation 2.6	6.1 score on a scale Standard Deviation 2.7

SECONDARY outcome

Timeframe: 1, 2, 3, and 4 Weeks

Population: Pre-specified confirmatory analyses assessed differences between the abstinent and monitoring arms only (see attached Statistical Analysis Plan).

A transformation of the proportion of hits and false alarms, providing an estimate of a subject's ability to detect the target sequences of digits after controlling for response bias (i.e., biases to respond or not respond irrespective of the stimuli on screen). This is a specific measure from the Rapid Visual Information Processing (RVP) module, which is part of the Cambridge Neuropsychological Test Automated Battery (CANTAB). The RVP module assesses sustained attention. Bounded continuous variable, ranging from 0 to 1, where higher scores indicate a greater ability to discriminate between targets and distractors.

Outcome measures

Measure	Abstinent n=54 Participants This group of cannabis users are agree to remain abstinent from cannabis use for 30 days. Abstinence: Cannabis users randomized to this condition will be enrolled in a contingency management intervention for 30 days of cannabis abstinence.	Monitoring n=66 Participants This group of cannabis users are not asked to change their cannabis use behavior.	Non-Users n=69 Participants This is a group of adolescents with little to no cannabis use history and were non-randomized.
Mean Difference in the Measure of Discriminability - A' From the Rapid Visual Information Processing (RVP) Module Averaged Over Weeks 1, 2, 3, and 4	0.94 score on a scale Standard Deviation 0.05	0.93 score on a scale Standard Deviation 0.06	0.92 score on a scale Standard Deviation 0.08

SECONDARY outcome

Timeframe: 1, 2, 3, and 4 Weeks

Population: Pre-specified confirmatory analyses assessed differences between the abstinent and monitoring arms only (see attached Statistical Analysis Plan).

The response latency for hits for each participant was defined as a summary (median) over the set of response times for all correct responses (identification of target 3-digit sequences). This is a specific measure from the Rapid Visual Information Processing (RVP) module, which is part of the Cambridge Neuropsychological Test Automated Battery (CANTAB). The RVP module assesses sustained attention. Response time variable in milliseconds (ms), ranging from 100 to 1900 ms, with higher values indicating slower performance in detecting targets.

Outcome measures

Measure	Abstinent n=54 Participants This group of cannabis users are agree to remain abstinent from cannabis use for 30 days. Abstinence: Cannabis users randomized to this condition will be enrolled in a contingency management intervention for 30 days of cannabis abstinence.	Monitoring n=66 Participants This group of cannabis users are not asked to change their cannabis use behavior.	Non-Users n=69 Participants This is a group of adolescents with little to no cannabis use history and were non-randomized.
Mean Difference in the Reponse Latency for Hits From the Rapid Visual Information Processing (RVP) Module Averaged Over Weeks 1, 2, 3, and 4	422 score on a scale Standard Deviation 51	428 score on a scale Standard Deviation 97	428 score on a scale Standard Deviation 78

Adverse Events

Abstinent

Serious events: 0 serious events

Other events: 49 other events

Deaths: 0 deaths

Monitoring

Serious events: 0 serious events

Other events: 46 other events

Deaths: 0 deaths

Non-Users

Serious events: 0 serious events

Other events: 31 other events

Deaths: 0 deaths

Serious adverse events

Adverse event data not reported

Other adverse events

Measure	Abstinent n=54 participants at risk This group of cannabis users are agree to remain abstinent from cannabis use for 30 days. Abstinence: Cannabis users randomized to this condition will be enrolled in a contingency management intervention for 30 days of cannabis abstinence.	Monitoring n=66 participants at risk This group of cannabis users are not asked to change their cannabis use behavior.	Non-Users n=69 participants at risk This is a group of adolescents with little to no cannabis use history and is non-randomized.
Gastrointestinal disorders Gastrointestinal disorders	1.9% 1/54 • Number of events 1 • Adverse event data was collected over 60 days. Adverse events were collected via systematic assessment. Adverse events were collected at each visit from the time the subject provided informed consent up to and including the last study visit using a standardized questionnaire. All adverse events volunteered, observed, or solicited were recorded in the adverse events CRF. Adverse events were recorded with the date of the event, event description, severity, expectedness, and assessment of relationship to study procedures.	7.6% 5/66 • Number of events 6 • Adverse event data was collected over 60 days. Adverse events were collected via systematic assessment. Adverse events were collected at each visit from the time the subject provided informed consent up to and including the last study visit using a standardized questionnaire. All adverse events volunteered, observed, or solicited were recorded in the adverse events CRF. Adverse events were recorded with the date of the event, event description, severity, expectedness, and assessment of relationship to study procedures.	1.4% 1/69 • Number of events 1 • Adverse event data was collected over 60 days. Adverse events were collected via systematic assessment. Adverse events were collected at each visit from the time the subject provided informed consent up to and including the last study visit using a standardized questionnaire. All adverse events volunteered, observed, or solicited were recorded in the adverse events CRF. Adverse events were recorded with the date of the event, event description, severity, expectedness, and assessment of relationship to study procedures.
General disorders General disorders	83.3% 45/54 • Number of events 92 • Adverse event data was collected over 60 days. Adverse events were collected via systematic assessment. Adverse events were collected at each visit from the time the subject provided informed consent up to and including the last study visit using a standardized questionnaire. All adverse events volunteered, observed, or solicited were recorded in the adverse events CRF. Adverse events were recorded with the date of the event, event description, severity, expectedness, and assessment of relationship to study procedures.	51.5% 34/66 • Number of events 50 • Adverse event data was collected over 60 days. Adverse events were collected via systematic assessment. Adverse events were collected at each visit from the time the subject provided informed consent up to and including the last study visit using a standardized questionnaire. All adverse events volunteered, observed, or solicited were recorded in the adverse events CRF. Adverse events were recorded with the date of the event, event description, severity, expectedness, and assessment of relationship to study procedures.	30.4% 21/69 • Number of events 25 • Adverse event data was collected over 60 days. Adverse events were collected via systematic assessment. Adverse events were collected at each visit from the time the subject provided informed consent up to and including the last study visit using a standardized questionnaire. All adverse events volunteered, observed, or solicited were recorded in the adverse events CRF. Adverse events were recorded with the date of the event, event description, severity, expectedness, and assessment of relationship to study procedures.
Injury, poisoning and procedural complications Injury, Poisoning and Procedural Complications	1.9% 1/54 • Number of events 1 • Adverse event data was collected over 60 days. Adverse events were collected via systematic assessment. Adverse events were collected at each visit from the time the subject provided informed consent up to and including the last study visit using a standardized questionnaire. All adverse events volunteered, observed, or solicited were recorded in the adverse events CRF. Adverse events were recorded with the date of the event, event description, severity, expectedness, and assessment of relationship to study procedures.	9.1% 6/66 • Number of events 7 • Adverse event data was collected over 60 days. Adverse events were collected via systematic assessment. Adverse events were collected at each visit from the time the subject provided informed consent up to and including the last study visit using a standardized questionnaire. All adverse events volunteered, observed, or solicited were recorded in the adverse events CRF. Adverse events were recorded with the date of the event, event description, severity, expectedness, and assessment of relationship to study procedures.	2.9% 2/69 • Number of events 2 • Adverse event data was collected over 60 days. Adverse events were collected via systematic assessment. Adverse events were collected at each visit from the time the subject provided informed consent up to and including the last study visit using a standardized questionnaire. All adverse events volunteered, observed, or solicited were recorded in the adverse events CRF. Adverse events were recorded with the date of the event, event description, severity, expectedness, and assessment of relationship to study procedures.
Musculoskeletal and connective tissue disorders Musculoskeletal and Connective Tissue Disorders	9.3% 5/54 • Number of events 5 • Adverse event data was collected over 60 days. Adverse events were collected via systematic assessment. Adverse events were collected at each visit from the time the subject provided informed consent up to and including the last study visit using a standardized questionnaire. All adverse events volunteered, observed, or solicited were recorded in the adverse events CRF. Adverse events were recorded with the date of the event, event description, severity, expectedness, and assessment of relationship to study procedures.	6.1% 4/66 • Number of events 6 • Adverse event data was collected over 60 days. Adverse events were collected via systematic assessment. Adverse events were collected at each visit from the time the subject provided informed consent up to and including the last study visit using a standardized questionnaire. All adverse events volunteered, observed, or solicited were recorded in the adverse events CRF. Adverse events were recorded with the date of the event, event description, severity, expectedness, and assessment of relationship to study procedures.	1.4% 1/69 • Number of events 1 • Adverse event data was collected over 60 days. Adverse events were collected via systematic assessment. Adverse events were collected at each visit from the time the subject provided informed consent up to and including the last study visit using a standardized questionnaire. All adverse events volunteered, observed, or solicited were recorded in the adverse events CRF. Adverse events were recorded with the date of the event, event description, severity, expectedness, and assessment of relationship to study procedures.
Psychiatric disorders Psychiatric Disorders	48.1% 26/54 • Number of events 35 • Adverse event data was collected over 60 days. Adverse events were collected via systematic assessment. Adverse events were collected at each visit from the time the subject provided informed consent up to and including the last study visit using a standardized questionnaire. All adverse events volunteered, observed, or solicited were recorded in the adverse events CRF. Adverse events were recorded with the date of the event, event description, severity, expectedness, and assessment of relationship to study procedures.	16.7% 11/66 • Number of events 11 • Adverse event data was collected over 60 days. Adverse events were collected via systematic assessment. Adverse events were collected at each visit from the time the subject provided informed consent up to and including the last study visit using a standardized questionnaire. All adverse events volunteered, observed, or solicited were recorded in the adverse events CRF. Adverse events were recorded with the date of the event, event description, severity, expectedness, and assessment of relationship to study procedures.	8.7% 6/69 • Number of events 9 • Adverse event data was collected over 60 days. Adverse events were collected via systematic assessment. Adverse events were collected at each visit from the time the subject provided informed consent up to and including the last study visit using a standardized questionnaire. All adverse events volunteered, observed, or solicited were recorded in the adverse events CRF. Adverse events were recorded with the date of the event, event description, severity, expectedness, and assessment of relationship to study procedures.
Respiratory, thoracic and mediastinal disorders Respiratory, Thoracic and Mediastinal Disorders	5.6% 3/54 • Number of events 3 • Adverse event data was collected over 60 days. Adverse events were collected via systematic assessment. Adverse events were collected at each visit from the time the subject provided informed consent up to and including the last study visit using a standardized questionnaire. All adverse events volunteered, observed, or solicited were recorded in the adverse events CRF. Adverse events were recorded with the date of the event, event description, severity, expectedness, and assessment of relationship to study procedures.	10.6% 7/66 • Number of events 7 • Adverse event data was collected over 60 days. Adverse events were collected via systematic assessment. Adverse events were collected at each visit from the time the subject provided informed consent up to and including the last study visit using a standardized questionnaire. All adverse events volunteered, observed, or solicited were recorded in the adverse events CRF. Adverse events were recorded with the date of the event, event description, severity, expectedness, and assessment of relationship to study procedures.	10.1% 7/69 • Number of events 7 • Adverse event data was collected over 60 days. Adverse events were collected via systematic assessment. Adverse events were collected at each visit from the time the subject provided informed consent up to and including the last study visit using a standardized questionnaire. All adverse events volunteered, observed, or solicited were recorded in the adverse events CRF. Adverse events were recorded with the date of the event, event description, severity, expectedness, and assessment of relationship to study procedures.

Additional Information

Randi M. Schuster, PhD

Massachusetts General Hospital

Phone: 617-643-6673

Email: rschuster@mgh.harvard.edu

Results disclosure agreements

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