What have population surveys revealed about substance use disorders and their co-morbidity with other mental disorders?

This paper reviews the epidemiology of alcohol and drug abuse and dependence as revealed in recent US general population surveys of the prevalence and correlates of mental disorders, the Epidemiologic Catchment Area (EGA) studies, and the National Comorbidity Study (NCS). These surveys indicate that mental disorders affect between a third and a half of people at some time in their lives, and around one in four in any year. Among the most common forms of mental disorder are phobias, alcohol use disorders, affective disorders and drug use disorders. There are marked gender differences in the prevalence of these disorders: substance use disorders and anti-social personality disorders predominate in men while affective and anxiety disorders predominate in women. The co-occurrence of substance use and other mental disorders is less common in the community than in the clinic because the presence of other mental disorders increases the chances of people with substance use disorders receiving specialist treatment. Only a minority of those with substance use and other mental disorders in the community are treated, with the more severe cases with multiple co-morbid mental disorders and manifest distress the most likely to be treated.