Morbidity risk for alcoholism and drug abuse in relatives of cocaine addicts.

The morbidity risks for alcoholism in the first-degree relatives of a cohort of male cocaine addicts with or without alcoholism comorbidity were studied. Of the 71 patients who participated in our study, 40 (56.3%) had a history of alcoholism and 37 (59.1%) a history of opioid abuse. Twenty-two patients (30.1%) also met criteria for a lifetime diagnosis of a major psychiatric disorder. Significant increases in morbidity risks for alcoholism were found among male relatives of cocaine addicts with comorbid alcohol dependence when compared with relatives of cocaine addicts with no alcohol comorbidity. Among fathers, risks were .69 vs .32 (z = 2.98, p < .003). Among brothers, risks were .38 vs .15 (z = 2.35, p < .03). Significantly increased risks were also observed in male relatives when probands with a psychiatric diagnosis were excluded from the analyses. Among female relatives, increases in morbidity risks were found but they failed to reach statistical significance. Two interpretations are consistent with these findings. One of these interpretations is that alcoholism is a disorder distinct from other addictions and has its own mode of transmission. The second interpretation is that the transmission of substance use disorders lacks specificity and that the substances selected are influenced by sociocultural or biological factors.