Substance abuse and mental disorders: the dual diagnoses concept.

The concept of "dual diagnoses" is reviewed along with its clinical implications. Prevalence studies report substance abuse in psychiatric populations as ranging between 20% and 75%, depending on reporting, demographic variables and the community availability of substances. On the other hand, 20% to 65% of alcoholics entering rehabilitation suffer from another major psychiatric disorder. The clinical impact of dual diagnoses involves the development and expression of psychiatric disorders depending on the choice of drugs, the severity of psychopathology and risk of assaultive behaviour, possible misdiagnosis such as the confusion between alcoholism and affective disorders, the increased use of psychiatric resources including emergency, an earlier onset of symptomatology and poorer prognosis. The evolutionary impact of the concept, reflected in successive psychiatric diagnostic classifications, is discussed along with its bridging influence between the fields of mental health and addictionology. Appropriate assessment tools along with treatment strategies are suggested. Effective features of a group process include a nonconfrontational approach with emphasis on education, an expectation of abstinence as a goal, a discussion of diagnoses and medication and lastly particular attention to vocational rehabilitation and constructive use of leisure time.