Association of comorbid psychopathology with the duration of cannabis use disorders

Risk factors for the development of cannabis use disorders (CUDs) have been well-researched. Comparatively little is known, however, about factors associated with the persistence of CUDs over time. This research explored whether the temporal sequencing of comorbid psychiatric disorders in relation to the onset of the index CUD episode were associated with the length of this episode. Four comprehensive diagnostic assessments were conducted between ages 16 and 30 with a large and regionally representative community sample (n = 816), among which 173 persons were diagnosed with a lifetime CUD. In separate unadjusted analyses, any internalizing disorder and any mood disorder with onset prior to that of the index CUD episode were each significantly and negatively associated with CUD duration. These effects, however, were reduced to trend level in adjusted analyses that controlled for putative confounders. Following the onset of the index CUD episode, the subsequent occurrence of any Axis I disorder, internalizing disorder, externalizing disorder, or other substance use disorder during the index CUD episode was significantly and positively associated with the duration of that episode in both unadjusted and adjusted analyses. These findings collectively suggest that the presence of internalizing-spectrum disorders prior to the onset of the index CUD episode affords some modest protection against protracted episodes, whereas the emergence of broad-spectrum psychopathology within the index CUD episode, most notably noncannabis substance use disorders, is associated with greater disorder persistence. The relevance of these findings for various motivational models of cannabis addiction is discussed.