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Member Research & Reports

Member Research & Reports

Brown: Marijuana Related Impairment Expectancies Reduce Risk Taking Behaviors

Evidence suggests that the pharmacologic effects of marijuana usage are associated with increased risk-taking and impulsive behaviors such as intoxicated driving. Additionally, the expectancy of potential impairment when using marijuana may also contribute to such behaviors. However, few studies have examined the potential effects of outcome expectancies on marijuana’s effect on impulsivity and risk-taking behaviors. With the current increase in marijuana use and related problems, a greater understanding of the relationship between marijuana intoxication and risky behavior is needed.

This study, led by Dr. Jane Metrik, associate professor of behavioral and social sciences at Brown University School of Public Health and faculty member in the Brown University Center for Alcohol and Addiction Studies, sought to determine if higher cognitive-behavioral impairment expectancies would be associated with lower levels of impulsivity and risk taking among individuals who received tetrahydrocannabinol (THC) and told they were given THC in comparison to those who did not receive THC or have THC-related expectancies.

To explore this phenomenon, the researchers recruited over 100 regular marijuana users, and randomized them to one of four experimental conditions: (1) told they were given THC and received THC, (2) told they were given THC and received a placebo, (3) told they were given a placebo and received THC, and (4) told they were given a placebo and received a placebo. After administration, participants filled out a self-report on marijuana outcome expectancies and completed multiple behavioral impulsivity tasks, such as the balloon analogue risk task (BART).

Participants who received THC and had higher expectancies of cognitive-behavioral impairment ultimately demonstrated lower risk-taking behaviors on the BART. There was no association found between cognitive-behavioral impairment expectancies and performance on the BART in those who received the placebo. Cognitive-behavioral impairment expectancies did not moderate the stimulus expectancy effect on the BART or other impulsivity measures.

Ultimately, this study builds on prior research suggesting that negatively valanced impairment expectancies lead to compensatory behavioral responses that reduce risky behaviors among users under the influence of marijuana.

This study was published in Drug and Alcohol Dependence, Volume 178, 2017.

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