Conditional substance abuse and dependence by diagnosis of mood or anxiety disorder or schizophrenia in the U.S. population.

BACKGROUND: Little is known about the association of various psychiatric disorders with the risk of developing dependence or abuse among users of various psychoactive substances (conditional dependence, CD; conditional abuse, CA).

OBJECTIVES: Evaluate the association of psychiatric disorders with CA only, CD only and CA+CD.

METHOD: Secondary analysis of data from 43,093 non-institutionalized US adults in the first wave (2001-2002) of the National Epidemiological Survey on Alcohol and Related Conditions. A structured diagnostic interview allowed classification by lifetime psychiatric diagnosis (DSM-IV criteria) and psychoactive substance use. Data were analyzed using weighted proportions, 95% CIs, and weighted logistic regression models to generate odds ratios (OR) adjusted for socio-demographic characteristics.

RESULTS: Psychiatric disorders were associated with higher prevalence of psychoactive substance use, regardless of type of disorder or substance. CA, CD and CA+CD prevalence rates were generally higher than unconditional prevalence rates among respondents with and without psychiatric disorders. Respondents with multiple disorders (mainly mood and anxiety disorders) had higher rates of CA+CD on most, but not all, psychoactive substances (e.g., not heroin), while schizophrenia was associated only with higher rates of tranquilizer CA+CD. Psychiatric disorders had few associations with CA only and CD only on psychoactive substances.

CONCLUSION: Study findings suggest that mood and anxiety disorders are associated with increased prevalence of substance use and increased transition from use to CA and CD, while schizophrenia is associated with increased transition from abstinence to use, especially for marijuana. Findings did not support the self-medication hypothesis of substance use disorders.