Subjective effects to cannabis are associated with use, abuse and dependence after adjusting for genetic and environmental influences.

BACKGROUND

Previous reports in adults have suggested that the effects experienced after cannabis use can be described in terms of positive and negative subtypes that are heritable and are associated with abuse and dependence. This study extends existing research by inclusion of adolescents and young adults in an offspring of twins design which makes it possible to take into account genetic and environmental risks for substance use disorder.

METHODS

Data were collected from 725 twin members of the Vietnam Era Twin Registry, 839 of their 12-32 year old biological offspring and 427 mothers. Offspring who had ever used cannabis (n=464) were asked the degree to which they typically experienced 13 subjective effects shortly after using cannabis. Latent class analysis (LCA) was used to derive subjective effect classes and logistic regression models were computed to test associations between subjective effect class and heavy cannabis use, abuse and dependence after adjusting for familial risk and psychopathology and sociodemographics.

RESULTS

The best fitting LCA model included 4 classes of responders which were characterized as 'high responders' (39%), 'positive responders' (28%), 'mixed/relaxed' (22%), and 'low responders' (11%). Compared to low responders, members of other classes were heavier users (OR range 3.0-11.8). Compared to mixed/relaxed responders and positive responders, high responders were more likely to have cannabis abuse and dependence.

CONCLUSIONS

Subjective reactions to cannabis use are associated with use to heavy use, abuse and dependence in adolescents and young adults. This association exists above and beyond the genetic vulnerability for problem cannabis use.