Cannabis
Conditions
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.
Detailed description
The proposed project is a randomized controlled trial to compare cognition and psychiatric disorder symptoms between monozygotic (MZ) twin pairs, who are concordant on frequency of cannabis use. Each twin, within the twin pair, will be randomly assigned to either contingency management (CM), monetary incentives provided to reinforce cannabis abstinence, or control, no changes in cannabis use required or reinforced. Participants in the CM condition will receive an increasing schedule of payments at each visit reinforcing continued cannabis abstinence. All participants will receive increases in the payment schedule for attendance of each subsequent assessment. Participants will be assessed on measures of cognition including attention, memory, and processing speed as well as anxiety, depression, and ADHD symptoms. In addition, at each visit participants will complete a qualitative and quantitative drug test. The qualitative drug test will be used to determine if new cannabis use has occurred since the last visit, and will determine if the participant receives payment for abstinence. The investigators will also use previously collected genotype for each participant. The first aim of this study is to characterize cognitive recovery, across all potential cognitive domains, using an experimental manipulation to achieve discordance between MZ twins on cannabis use. The hypothesis for the first aim is that the abstinent group will have greater improvements in memory and processing speed compared to controls. However, there will not be any group differences between the abstinent group and the control group on attention, language, and executive function performance. The second aim of the proposed project is to characterize psychiatric disorder symptoms by comparing psychiatric disorder symptom changes among the cannabis abstaining twin to their cannabis using co-twin across 42 days. The abstinent group will endorse more psychiatric symptoms during the withdrawal period (up to 14 days) but will endorse fewer psychiatric symptoms at day 28 and 42 compared to the control group. The third aim (exploratory) of the proposed project is to examine how genetic risk for psychiatric disorders interacts with environment (i.e., cannabis abstinence versus continued use) to influence cognitive functioning. The hypothesis for aim 3 is that anxiety, depression, and ADHD polygenic scores will be more strongly associated with cognitive outcomes in the control group compared to the abstinent group.
Interventions
BEHAVIORALContingency management
Participants will be paid to abstain from cannabis use.
Sponsors
University of Colorado, Denver
University of Colorado, Boulder
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
BASIC_SCIENCE
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
31 Years to 47 Years
Healthy volunteers
Yes
Inclusion criteria
1. Monozygotic (MZ) twin pair, in which both twins are willing to participate 2. MZ twin pair must be concordant in their frequency of cannabis use (+/- 2 days) 3. Cannabis use at least 1x per week on most weeks 4. Cannabis use in the past 7 days at the baseline visit 5. Positive qualitative urine toxicology at baseline for THC 6. Located within the state of Colorado
Exclusion criteria
1\) Discordance in the twin pairs on a significant, adverse experience, like traumatic brain injury.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Change in attention performance | Change from baseline to day 42 | Flanker Inhibitory Control and Attention Test on NIH Toolbox: Composite score of accuracy and reaction time |
| Change in episodic memory | Change from baseline to day 42 | Picture Sequence Memory Test on NIH Toolbox: Cumulative number of correct adjacent pairs |
| Change in working memory | Change from baseline to day 42 | List Sorting Working Memory Test on NIH Toolbox: Total items correct across all trials |
| Change in receptive vocabulary | Change from baseline to day 42 | Picture Vocabulary Test on NIH Toolbox: Computer adaptive testing |
| Change in reading decoding | Change from baseline to day 42 | Oral Reading Recognition Test: Number of letters and words read correctly |
| Change in immediate memory/verbal learning | Change from baseline to day 4 | Auditory Verbal Learning Test on NIH Toolbox: Total number of words recalled |
| Change in pattern comparison processing speed | Change from baseline to day 42 | Pattern Comparison Processing Speed Test: Total number of correct responses |
| Change in oral symbol digit test processing speed | Change from baseline to day 42 | Oral Symbol Digit Test on NIH Toolbox: Total number of correctly identified symbols |
| Change in attention and executive function | Change from baseline to day 42 | Dimensional Change Card Sort Test on NIH Toolbox: Composite score of accuracy and correct answers |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Change in anxiety symptoms | Change from baseline to day 42 | Beck Anxiety Inventory: Total score. Scores range from 0-63 and higher scores indicate higher levels of anxiety. |
| Change in depressive symptoms | Change from baseline to day 42 | Beck Depression Inventory: Total score. Scores range from 0-63 and higher scores indicate greater levels of depression. |
| Change in attention deficit/hyperactivity disorder symptoms | Change from baseline to day 42 | Adult Self-Report Scale: Total score. Scores range from 0-72 and higher scores indicate greater level of symptoms of attention deficit/hyperactivity disorder. |
Countries
United States
Contacts
PRINCIPAL_INVESTIGATORJ. Megan Ross, Ph.D.
University of Colorado, Denver
Outcome results
None listed