Subjective Reactions to Cannabis Use Associated with Use and Dependence
Subjective responses to drug use have been shown to predict later heavy use and abuse. For example, considerable data suggest that a lower response to alcohol is associated with long-term heavy drinking. But less is known about subjective responses to cannabis in adolescent and young adults and their association with use and abuse/dependence. Using data from VA's Vietnam Era Twin Registry (VETR), investigators in this study were able to adjust for genetic and environmental factors while assessing the effects of cannabis use on 464 VETR offspring (adolescents and young adults age 12-32). These offspring were then categorized into four classes (or subsets) of cannabis responders: high (39%), positive (28%), mixed/relaxed (22%), and low (11%). Other variables in this study included: conduct disorder, demographics, major depression, alcohol abuse, nicotine dependence, and the use of any illicit drug other than marijuana.
Findings show that cannabis use, abuse, and dependence are associated with the type of subjective response even after adjusting for genetic influence and environmental factors, as well as demographic and psychiatric variables. For example, compared to mixed/relaxed responders and positive responders, high responders were more likely to have cannabis abuse and dependence. In addition, compared to low responders, members of the other three classes were heavier users of cannabis. Among sociodemographic variables, only male gender was associated with subjective response, as evidenced by a lower prevalence of males in mixed/relaxed and low responder classes as compared to high and positive responder classes. Though not statistically significant, the prevalence of conduct disorder, major depression, and alcohol dependence was highest in offspring who were members of the high responder class. These findings will help determine where public health efforts should be focused.
Scherrer J, Grant J, Duncan A, et al. Subjective Effects to Cannabis are Associated with Use, Abuse, and Dependence after Adjusting for Genetic and Environmental Influences. Drug and Alcohol Dependence November 1, 2009;105(1-2):76-82.
This study was partly funded by HSR&D, and Dr. Scherrer is supported by an HSR&D Career Development Award.