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

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.


Eligibility Criteria:
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)