Similar to NESARC findings (17), 12-month and lifetime cannabis use disorders were strongly and consistently associated with other substance and mental disorders. Thus, despite the increasingly normative nature of marijuana use and the increased adult prevalence of cannabis use disorders, those with cannabis use disorders continue to be vulnerable to other common mental disorders. In patient settings, those with drug and psychiatric disorders often exhibit more persistent, severe, and treatment-resistant symptoms than patients with drug disorders only (62). Research indicates that the best treatment for such comorbid conditions is concurrent treatment for both disorders (62). Therefore, study findings indicate an increased need for settings that provide evidence-based treatments for both conditions. Further, multivariable investigation indicates two latent transdiagnostic domains of comorbidity, the internalizing (INT) and externalizing (EXT) (63) domains. EXT is characterized by antisocial personality disorder and substance disorders; INT is characterized by distress (major depression, dysthymia, generalized anxiety) or fear (panic, social phobia, specific phobia). These domains have been replicated across gender and race/ethnic groups (64, 65). Given the changing legal and attitudinal climate in the U.S. regarding marijuana
