The Epidemiology of DSM-5 Cannabis Use Disorders Among U.S. Adults: Science to Inform Clinicians Working in a Shifting Social Landscape.

The study of cannabis use disorders has become urgent because of several factors: increasing cannabis legalization in multiple states and jurisdictions (1), the high and increasing prevalence of cannabis use (2), prospective evidence of the impact of cannabis use on future risk of psychiatric disorders (3), and evidence for multiple deleterious effects of cannabis exposure (4). It is against this backdrop of a rapidly changing legal landscape and emerging evidence of harms from cannabis use that we should consider Hasin and colleagues’ rigorous analysis of the prevalence, demographic characteristics, psychiatric comorbidity, disability, and treatment for DSM-5 cannabis use disorders in the U.S. adult population (5). This study will go a long way toward helping psychiatrists and all clinicians to treat patients more effectively and participate more actively in policy discussions. Going into this study,weknew that 12.5%of persons age 18 or older in the United States reported past-year use of cannabis in2013 (2). This prevalence is about 19%higher than the 10.5% found in 2002 (2), an increase that was likely fueled, at least inpart, by the inverse relationshipbetweencannabis use and theperceptionofharmfulness (6). This trend isproblematic because cannabis use is associated with increased risk for a number of adverse cognitive, psychiatric, physical, and social effects, including comorbid mental disorders (3, 4). The increasing prevalence of cannabis use combinedwith the evolving definition of cannabis use disorder in the revised DSM-5 nomenclature warranted reassessment of cannabis epidemiology. For instance, changes in DSM-5 (compared with DSM-IV) included the addition of withdrawal as a recognized component of cannabis use disorder. DSM-5 also included universal changes for all substance use disorders, including cannabis use disorders. Of particular note, DSM-5 eliminated the DSM-IV abuse and dependence disorders in favor of a single, unified substance use disorder with severity determined by the number of criteria endorsed (7). Hasin and colleagues report findings from the landmark National Epidemiologic Survey on Alcohol and Related Conditions–III, which included psychiatric interview data from36,309personsage 18 orolder in2012–2013, todetermine the rates ofDSM-5 cannabis usedisorder and its correlates (5). Cannabis use disorder was found to be prevalent, with a pastyear rate of 2.5% and a lifetime rate of 6.3%. Rateswere higher among men, Native Americans, unmarried persons, younger persons, and thosewith low incomes.Comorbiditywas found to be common, with strong associations of cannabis use disorder with other substance use disorders, affective disorders, anxiety disorders, and personality disorders. Factual information about cannabis use disorder is sorely needed, and the article by Hasin and colleagues is likely to become the standard reference on the topic. Particularly compelling is the information about demographic correlates and comorbidity. The demonstration of strong associations with other substance use disorders (related to tobacco, alcohol, and other illicit drugs) and other psychiatric disorders (personality, anxiety, and mood) is consistent with findings from previous studies based on DSM-III, DSM-III-R, and DSM-IV criteria, but the addition of information about how increasing severity of DSM-5 cannabis usedisorder is reflected in the increasing strength of the associations with these comorbidpsychiatric disorders is quite novel. Hasin and colleagues found that increasing DSM-5 cannabis use disorder severity was also associated with poorer functioning and stronger correlation with risk factors (5). It appears that the severity subtypes implemented in DSM-5 are reliable predictors of such associations. These findings suggest that clinical problems associated with cannabis use disorder exist along a severity continuum, like the disorder itself. The low rates of treatment documented by Hasin and colleagues are also noteworthy (5). Only 13.7% of adults with a lifetime cannabis use disorder ever sought any type of treatment or intervention. Even among those with a severe disorder, only 24.3% reported seeking any such assistance. Needed are both effective interventions, including medications, for cannabis use disorders and increased patient motivation to seek such care. Future work might benefit from a longitudinal design. While cross-sectional research suchas theworkbyHasin and colleagues (5) helps to demonstrate important correlates of disorder, details about possible reasons for the associations Increasing DSM-5 cannabis use disorder severity was also associated with poorer functioning and stronger correlation with risk factors.