Cannabis use disorders in the USA: prevalence, correlates and co-morbidity.

BACKGROUND: The purpose of this study was to present 12-month and lifetime estimates of the prevalence, sociodemographic and clinical correlates, and psychiatric co-morbidity of DSM-IV cannabis abuse and dependence.

METHOD: Data were derived from a large nationally representative survey (n=43093) of US adults.

RESULTS: The prevalence of 12-month and lifetime DSM-IV cannabis abuse (1.1% and 7.2%) exceeded the corresponding rates of cannabis dependence (0.3% and 1.3%). Being male, Native American, widowed/separated/divorced, and residing in the West increased the odds whereas being Black, Asian or Hispanic decreased the odds of cannabis abuse and dependence. Cannabis dependence was significantly associated with low income. Ages of onset for both cannabis use disorders occurred in adolescence and the majority of individuals with these disorders remained untreated. Co-morbidity was high between cannabis use disorders and other Axis I and II disorders.

CONCLUSIONS: Cannabis use disorders continue to present a widespread and serious personal and public health problem. Native Americans were found to have high rates of cannabis use disorders, warranting closer attention to the mental health needs of this subgroup. Associations between cannabis abuse and dependence and Axis I and II disorders were strong, signaling the need for more comprehensive assessment of individuals with cannabis use disorders. Further controlled treatment studies are needed, especially among co-morbid individuals, in view of growing evidence of the adverse personal, medical and societal impacts of cannabis use disorders in the USA.