Mental health differences between frequent cannabis users with and without dependence and the general population

Abstract

Aims: To compare the prevalence of mental disorders between frequent cannabis users with and without dependence and the general population. Design: Cross-sectional comparison of interview data. Setting: Enriched community sample of frequent cannabis users and a representative sample of non-users and non-frequent users from the general population. Participants: A total of 521 young adult (aged 18-30 years) frequent cannabis users, 252 of whom were with DSM-IV cannabis dependence (D+) and 269 without DSM-IV cannabis dependence (D-), and 1072 young adults from the general population. Measurements: Multinomial logistic regression was used to compare groups regarding the presence of DSM-IV mental disorders. Detailed measures of cannabis use, childhood adversity and other substance use were considered confounders. Findings: Compared with the general population, externalizing disorders were more prevalent in D- [odds ratio (OR)=8.91, P<0.001] and most prevalent in D+ (OR=17.75, P<0.001), but internalizing disorders were associated only with D+ (mood OR=4.15, P<0.001; anxiety OR=2.20, P=0.002). Associations were attenuated (and often became non-significant) after correction for childhood adversity and substance use other than cannabis. However, the prevalence of mental disorders remained higher in D+ compared with D- (OR=2.40, P<0.001), although cannabis use patterns were remarkably similar. Conclusions: Cannabis use patterns, childhood adversity and the use of other substances are similar in dependent and non-dependent frequent cannabis users. With the exception of more externalizing disorders, the mental health condition of non-dependent frequent cannabis users is similar to that of the general population, whereas it is worse in dependent frequent cannabis users. © 2013 Society for the Study of Addiction.