This study will use a randomized controlled design to test whether 30 days of cannabis abstinence, compared to 30 days of monitoring, is associated with improvements in cognitive functioning. Non-using controls will also be enrolled to determine the clinical significance of any cognitive improvements with abstinence.
This is a 5-year randomized, longitudinal trial of cannabis abstinence designed to determine (1) if performance improves with abstinence beyond that observed with continued cannabis use, and if so, (2) when during abstinence cognitive improvement occurs, and (3) whether performance in abstinent individuals "returns" to performance levels observed in non-using peers. We hypothesized that abstinent adolescent cannabis users would have more neurocognitive improvement over four weeks compared to non-abstinent cannabis users, and performance would continuously improve throughout four weeks of abstinence. We will recruit 210 adolescents with and without regular cannabis use. Eligible cannabis users will be randomized to either a contingency management intervention which will incentivize 4 weeks of cannabis abstinence (n = 70), or non-contingent monitoring with no abstinence requirement (n = 70). All participants (including non-users; n = 70) will complete cognitive assessments, toxicology testing, self-report questionnaires and semi-structured mood and substance use interviews during the 4-week study as well as one 30-day follow-up visit. Abstinence will be indexed by decreasing levels of cannabis metabolites in urine.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
OTHER
Masking
NONE
Enrollment
201
Cannabis users randomized to this condition will be enrolled in a contingency management intervention for 30 days of cannabis abstinence.
Massachusetts General Hospital
Boston, Massachusetts, United States
Mean Difference in the Total Number of Errors From Paired Associates Learning (PAL) Module Averaged Over Weeks 1, 2, 3, and 4
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.
Time frame: 1, 2, 3, and 4 Weeks
Mean Difference in First Attempt Memory Score From Paired Associates Learning (PAL) Module Averaged Over Weeks 1, 2, 3, and 4
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.
Time frame: 1, 2, 3, and 4 Weeks
Mean Difference in Forward Span Length From Spatial Span (SSP) Module Averaged Over Weeks 1, 2, 3, and 4
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.
Time frame: 1, 2, 3, and 4 Weeks
Mean Difference in Reverse Span Length From Spatial Span (SSP) Module Averaged Over Weeks 1, 2, 3, and 4
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.
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Time frame: 1, 2, 3, and 4 Weeks
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
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.
Time frame: 1, 2, 3, and 4 Weeks
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
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.
Time frame: 1, 2, 3, and 4 Weeks
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
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.
Time frame: 1, 2, 3, and 4 Weeks
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
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.
Time frame: 1, 2, 3, and 4 Weeks
Mean Difference in the Total Number Incorrect From the Multitasking Test (MTT) Module Averaged Over Weeks 1, 2, 3, and 4
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.
Time frame: 1, 2, 3, and 4 Weeks
Mean Difference in the Response Latency From the Multitasking Test (MTT) Module Averaged Over Weeks 1, 2, 3, and 4
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.
Time frame: 1, 2, 3, and 4 Weeks
Mean Difference in the Incongruency Cost From the Multitasking Test (MTT) Module Averaged Over Weeks 1, 2, 3, and 4
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.
Time frame: 1, 2, 3, and 4 Weeks
Mean Difference in the Multitasking Cost From the Multitasking Test (MTT) Module Averaged Over Weeks 1, 2, 3, and 4
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.
Time frame: 1, 2, 3, and 4 Weeks
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
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.
Time frame: 1, 2, 3, and 4 Weeks
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
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.
Time frame: 1, 2, 3, and 4 Weeks
Mean Difference in Stop Signal Reaction Time From Stop Signal Task (SST) Module Averaged Over Weeks 1, 2, 3, and 4
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.
Time frame: 1, 2, 3, and 4 Weeks
Mean Difference in the Total Number of Between Errors From the Spatial Working Memory (SWM) Module Averaged Over Weeks 1, 2, 3, and 4
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.
Time frame: 1, 2, 3, and 4 Weeks
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
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.
Time frame: 1, 2, 3, and 4 Weeks
Mean Difference in the Measure of Discriminability - A' From the Rapid Visual Information Processing (RVP) Module Averaged Over Weeks 1, 2, 3, and 4
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.
Time frame: 1, 2, 3, and 4 Weeks
Mean Difference in the Reponse Latency for Hits From the Rapid Visual Information Processing (RVP) Module Averaged Over Weeks 1, 2, 3, and 4
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.
Time frame: 1, 2, 3, and 4 Weeks