Impact of Reduced Cannabis Use on Functional Outcomes (R33 Phase)

Study Overview
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Brief Summary
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Nearly 20 million Americans report use of cannabis in the past month, and heavy cannabis use has increased by nearly 60% in the U.S. since 2007. Heavy cannabis use is associated with lower educational attainment, reduced physical activity, increased rates of addiction and unemployment, and neuropsychological deficits. Studies suggest that cannabis use is also associated with increased mental health symptoms, drugged driving, and traffic accidents. While there is evidence that sustained abstinence can lead to improvements in the functional outcomes of former users, the degree to which reductions alone (i.e., not sustained abstinence) in cannabis use might be associated with positive changes in functional outcomes is unknown. This is a critical gap in the literature, as many interventions for cannabis and other drugs are associated with decreases in frequency and quantity of use, but fail to achieve an effect on overall abstinence rates. The objective of the present research is to use ecological momentary assessment (EMA), a real-time, naturalistic data collection method, to prospectively study the impact of reduced cannabis use on functional outcomes in heavy cannabis users. Contingency management (CM) will be used to promote reductions in frequency and quantity of cannabis use. CM is an intensive behavioral therapy that is highly effective at producing short-term reductions in illicit drug use. We have recently developed a novel approach that leverages mobile technology and recent developments in cannabis testing. We have pilot-tested this approach with heavy cannabis users and found that it is an acceptable and feasible method. The present research will use this technology in conjunction with EMA methods to study the impact of reduced cannabis use on key functional outcomes. Our central hypothesis is that reductions in frequency and quantity of cannabis use will lead to positive changes in cannabis users' mental health, self-efficacy, physical activity, working memory, health-related quality of life, and driving behavior. The rationale for this research is that it will provide the first and only real-time data concerning the potential impact of reductions in cannabis use on functional outcomes. As such, the findings from the present research will directly inform ongoing efforts to include reductions in illicit drug use as a valid, clinically-meaningful outcome measure in clinical trials of pharmacotherapies for the treatment of substance use disorders.

Official Title
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Impact of Reduced Cannabis Use on Functional Outcomes (R33 Phase)

Conditions
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Cannabis, Cannabis Use

Intervention / Treatment
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* Behavioral: Mobile contingency management


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Report 40 or more days of cannabis use (other than ingested cannabis, i.e., edibles) in past 90 days Can speak and write fluent conversational English Are between 18 and 80 years of age Are willing to attempt to reduce frequency of cannabis use Complete at least 10 of the 14 nightly diaries during the ad lib phase of the study procedures. Exclusion Criteria: Are expected to have an unstable medication regimen during the study Are currently receiving non-study treatment for cannabis use disorder Are pregnant or become pregnant Meet criteria for a serious mental illness (e.g., bipolar disorder, schizophrenia) Meet criteria for a substance use disorder other than nicotine or cannabis use disorders Are currently imprisoned or in psychiatric hospitalization or become imprisoned or in psychiatric hospitalization Report imminent risk for suicide or homicide Meet criteria for bio-verified sustained abstinence (i.e., all of their saliva tests are negative during the 6-week experimental phase of the study)

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 80 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Reduced Use Condition<br>Participants in the reduced use condition will be provided mobile contingency management, in which they are paid to provide marijuana saliva readings that suggest they have been abstinent from marijuana use. | Behavioral: Mobile contingency management<br>* Mobile contingency management is a mobile-phone based behavioral therapy that provides positive reinforcement (i.e., money) for abstinence that is highly effective at reducing substance use.<br>* Other names: mCM;|
| No Intervention: Control Condition<br>Participants in the control condition will be asked to provide marijuana saliva readings, but they are not paid for abstinent readings. Instead, their payments are yoked to the average amount of payment made by two participants in the reduced use condition. | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in mental health symptoms | Mental health symptoms will be measured by the 90-item Symptom Checklist (SCL-90). This measure has a scoring range of 0 to 360, with lower scores indicating lower distress related to mental health. | Baseline and post-treatment (approximately eight weeks) | 
| Change in self-reported self-efficacy | Self-efficacy will be measured by the Marijuana Reduction Strategies Self-Efficacy Scale. This measure has a scoring range of 0 to 84, with higher scores indicating increased self-efficacy. | Baseline and post-treatment (approximately eight weeks) | 
| Change in physical activity as measured by the International Physical Activity Questionnaire | Physical activity will be measured using a continuous score on the International Physical Activity Questionnaire. The score is calculated by multiplying metabolic equivalents times minutes per day times days per week. Higher scores indicate increased physical activity. | Baseline and post-treatment (approximately eight weeks) | 
| Change in physical activity as measured by the Baecke Physical Activity Questionnaire | Physical activity will be measured using the Baecke Physical Activity Questionnaire. Scores range from 3 to 15, with higher scores indicating increased physical activity. | Baseline and post-treatment (approximately eight weeks) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in health-related quality of life, WHOQOL-BREF | Health-related quality of life will be measured with the World Health Organization Quality of Life Brief (WHOQOL-BREF). The measure has a scoring range of 0 to 100, with higher scores denoting a higher quality of life. | Baseline and post-treatment (approximately eight weeks) | 
| Change in visual working memory | Visual working memory will be measured by the Visual Working Memory Index of Wechsler Memory Scale, which is comprised of the Symbol Span and Spatial Addition subtests. Higher scores indicate improved visual working memory. | Baseline and post-treatment (approximately eight weeks) | 
| Change in auditory working memory | Auditory working memory will be measured by the Auditory Working Memory Index of Wechsler Memory Scale, which is comprised of the Digit Span and Letter-Number Sequencing subtests. | Baseline and post-treatment (approximately eight weeks) | 
| Change in impulsivity as measured by delay discounting | Impulsivity will be measured with a delay discounting task. Lower scores on the task indicate lower impulsivity. | Baseline and post-treatment (approximately eight weeks) | 
| Change in impulsivity as measured by the Iowa Gambling Task | Impulsivity will be measured with the Iowa Gambling Task. Higher scores indicate lower impulsivity. | Baseline and post-treatment (approximately eight weeks) | 
| Change in impulsivity as measured by the Balloon Analogue Risk Task | Impulsivity will be measured with the Balloon Analogue Risk Task. Higher scores indicate higher impulsivity. | Baseline and post-treatment (approximately eight weeks) | 
| Change in impulsivity as measured by self-report | Self-reported impulsivity will be measured with the Urgency, Premeditation (lack of), Perserverance (lack of), Sensation Seeking, Positive Urgency, Impulsive Behavior Scale (UPPS-P). The measure has a score range of 59 to 236. Higher scores indicate higher impulsivity. | Baseline and post-treatment (approximately eight weeks) | 
| Change in number of days of drugged driving | Number of days of drugged driving in the past month will be self-reported by participants using a Timeline Follow-Back Interview. | Baseline and post-treatment (approximately eight weeks) |