Background. This study addressed the prevalences, correlates, co-morbidity and disability of DSM-IV generalized anxiety disorder (GAD) and other psychiatric disorders in a large national survey of the general population, the National Institute on Alcohol Abuse and Alcoholism's (NIAAA) National Epidemiologic Survey on Alcohol and Related Conditions (NESARC). The study presents nationally representative data, for the first time, on prevalence, correlates, co-morbidity, and comparative disability of DSM-IV GAD.

Method. Data are taken from a large (n=43093) representative sample of the adult USA population.

Results. Prevalences of 12-month and lifetime GAD were 2·1% and 4·1%. Being female, middle-aged, widowed/separated/divorced, and low income increased risk, while being Asian, Hispanic, or Black decreased risk. GAD was highly co-morbid with substance use, and other anxiety, mood, and personality disorders. Co-morbidity in GAD was not substantially greater than for most other Axis I and II disorders. Disability and impairment in pure GAD were equivalent to pure mood disorders, but significantly greater than in pure substance use, and other anxiety and personality disorders. Individuals co-morbid for GAD and each mood disorder were more disabled than those with pure forms of GAD or each mood disorder. When co-morbid with GAD, nicotine dependence and other anxiety and personality disorders were not associated with increased disability over that associated with pure GAD, but GAD did show increased disability over that due to each of these disorders in pure form.

Conclusions. Associations between GAD and Axis I and II disorders were strong and significant, with variation among specific disorders. Results strongly support GAD as an independent disorder with significant impairment and disability.