Changes in Cognition and Psychiatric Disorder Symptoms During Cannabis Abstinence Using a Novel Discordant Twin Design

NCT05160688 | Enrolling By Invitation

• 1 other identifier: 21-4899
• Study Type: interventional
• Target: 100
• Locations: 1 country
• Sites: 1

Brief Summary

This study will test whether 42 days of cannabis abstinence, compared to continued cannabis use, is associated with improvements in cognition and psychiatric disorder symptoms. Identical twins, who are concordant on cannabis use, will be experimentally-manipulated to be discordant for 42 days. Each twin, within a twin pair, will be randomly assigned to either the contingency management condition, incentive-based protocol to promote cannabis abstinence, or control condition, no changes in cannabis use requested.

Conditions

Cannabis

Outcome Measures

Primary Outcomes (9)

• Change in attention performance

  Flanker Inhibitory Control and Attention Test on NIH Toolbox: Composite score of accuracy and reaction time

  Change from baseline to day 42

• Change in episodic memory

  Picture Sequence Memory Test on NIH Toolbox: Cumulative number of correct adjacent pairs

  Change from baseline to day 42

• Change in working memory

  List Sorting Working Memory Test on NIH Toolbox: Total items correct across all trials

  Change from baseline to day 42

• Change in receptive vocabulary

  Picture Vocabulary Test on NIH Toolbox: Computer adaptive testing

  Change from baseline to day 42

• Change in reading decoding

  Oral Reading Recognition Test: Number of letters and words read correctly

  Change from baseline to day 42

• Change in immediate memory/verbal learning

  Auditory Verbal Learning Test on NIH Toolbox: Total number of words recalled

  Change from baseline to day 4

• Change in pattern comparison processing speed

  Pattern Comparison Processing Speed Test: Total number of correct responses

  Change from baseline to day 42

• Change in oral symbol digit test processing speed

  Oral Symbol Digit Test on NIH Toolbox: Total number of correctly identified symbols

  Change from baseline to day 42

• Change in attention and executive function

  Dimensional Change Card Sort Test on NIH Toolbox: Composite score of accuracy and correct answers

  Change from baseline to day 42

Secondary Outcomes (3)

• Change in anxiety symptoms

  Change from baseline to day 42

• Change in depressive symptoms

  Change from baseline to day 42

• Change in attention deficit/hyperactivity disorder symptoms

  Change from baseline to day 42

Study Arms (2)

Contingency management

EXPERIMENTAL

Contingency management (CM) is an incentive-based intervention providing patients with tangible rewards as reinforcement for positive behaviors like abstinence from drug use. Incentives are provided with each urine sample that is drug-free and are increased with each subsequent drug-free urine sample. Participants in the CM condition will receive increasing payments for abstinence: $30 on day 3, $45 on day 5, $60 on day 7, $75 on day 14, $90 on day 21, $105 on day 28, and $120 on day 42. Participants in both conditions also receive increasing payment for visit attendance: $10 on day 1, $15 on day 3, $20 on day 5, $25 on day 7, $30 on day 14, $35 on day 21, $45 on day 28, and $55 on day 42. At the end of the baseline visit, participants in the CM condition will sign a behavioral contract with study staff that clearly outlines expectations as well as the payment schedule.

Behavioral: Contingency management

No intervention

NO INTERVENTION

Participants in this condition will be monitored and will not receive any compensation for cannabis abstinence.

Interventions

Contingency management BEHAVIORAL

Participants will be paid to abstain from cannabis use.

Contingency management

Eligibility Criteria

• Age: 31 Years - 47 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• Monozygotic (MZ) twin pair, in which both twins are willing to participate
• MZ twin pair must be concordant in their frequency of cannabis use (+/- 2 days)
• Cannabis use at least 1x per week on most weeks
• Cannabis use in the past 7 days at the baseline visit
• Positive qualitative urine toxicology at baseline for THC
• Located within the state of Colorado

You may not qualify if:

• \) Discordance in the twin pairs on a significant, adverse experience, like traumatic brain injury.

Sponsors & Collaborators

• University of Colorado, Denver: lead
• University of Colorado, Boulder: collaborator

Study Sites (1)

Jessica M Ross

Aurora, Colorado, 80045, United States

Location

MeSH Terms

Conditions

Marijuana Abuse

Condition Hierarchy (Ancestors)

Substance-Related Disorders; Chemically-Induced Disorders; Mental Disorders

Study Officials

• J. Megan Ross, Ph.D.

  University of Colorado, Denver

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: BASIC SCIENCE
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: November 19, 2021
• First Posted: December 16, 2021
• Study Start: May 5, 2023
• Primary Completion: April 1, 2026
• Study Completion: April 1, 2026
• Last Updated: February 12, 2026

Record last verified: 2026-02

Data Sharing

• IPD Sharing: Will not share

Locations

US (1)