The diagnosis of alcohol and cannabis dependence in cocaine dependents and alcohol dependence in their families.

Genetic research in alcoholism has made major advances in recent decades. Twin, adoption, high-risk and familial studies have demonstrated an inheritance factor in alcoholism. Few studies have demonstrated a genetic predisposition to cocaine and cannabis dependence. Two hundred and sixty-three inpatients were given a structured psychiatric interview retrospectively (150) and prospectively (113) to obtain DSM-III-R diagnosis of cocaine, alcohol and cannabis dependence disorders in the inpatients and of alcohol dependence in family members. Our study reveals a large number of cocaine dependents with a positive family history for alcohol dependence. Approximately 50% of cocaine addicts had at least a first or second degree relative with a diagnosis of alcohol dependence when studied by the family history and study methods. As many as 89% of cocaine dependents diagnosed by DSM-III-R criteria for cocaine dependence qualified for other alcohol and drug dependence diagnoses. Our study finds a high prevalence of alcohol (67% and 89%) and cannabis dependence (51% and 46%) in patients with cocaine dependence. Previous reports regarding alcohol and other drug dependence among cocaine dependents and their families are few and inconclusive. The diagnosis of other drug and alcohol dependence in cocaine dependence and in family members of cocaine dependents has important impact on etiology, prognosis and treatment.