DUAL DIAGNOSIS - A REVIEW OF ETIOLOGIC THEORIES

The etiology of the high prevalence of substance use disorders in pati ents with severe mental illness (schizophrenia or biopolar disorder) i s unclear. We review the evidence of different theories of increased c omorbidity, organized according to four general models: common factor models, secondary substance use disorder models, secondary psychiatric disorder models, and bidirectional models. Among common factor models , evidence suggests that antisocial personality disorder accounts for some increased comorbidity. Among secondary substance use disorder mod els, there is support for the supersensitivity model, which posits tha t biological vulnerability of psychiatric disorders results in sensiti vity to small amounts of alcohol and drugs, leading to substance use d isorders. There is minimal support for the self-medication model, but the accumulation of multiple risk factors related to mental illness, i ncluding dysphoria, may increase the risk of substance use disorder. S econdary psychiatric disorder models remain to be convincingly demonst rated. Bidirectional models have not been systematically examined. Fur ther clarification of etiologic factors, including the identification of subtypes of dual diagnosis, may have implications for developing mo re effective prevention efforts and treatment. (C) 1998 Elsevier Scien ce Ltd.