Association between Severity of Cannabis Dependence and Depression

Objective. The aim of the current study was to investigate the relationship between self-reported severity of cannabis dependence and symptoms of depression. Method. The lifetime diagnoses of depression and cannabis misuse (abuse and/or dependence) were obtained from 50 participants recruited from the general community, using a self-completed diagnostic interview (CIDI-Auto 2.1). The lifetime severity of cannabis dependence was established using a standard questionnaire, Severity of Dependence Scale (SDS). Results. Of the 19 participants with mental illness diagnoses, 14 (74%) reported depression symptoms. The 14 participants with depression diagnoses had significantly more cannabis misuse diagnoses and significantly higher SDS scores compared to those without mental illness diagnoses (N = 31). SDS scores significantly predicted presence or absence of CIDI depression diagnoses with a 69% overall rate of correct predictions. As SDS scores increased the odds of classification into depressed versus non-depressed groups was 1.3 (95% C.I. 1.02-1.57). Conclusion. The presence of lifetime depression symptoms is associated with higher lifetime severity of cannabis dependence and more lifetime cannabis misuse symptoms in otherwise healthy research volunteers.