Psychiatric disorders in first-degree relatives of patients with opiate dependence.

High rates of psychiatric disorders, particularly major depression, alcoholism, drug-use disorder and antisocial personality disorder in the relatives of opiate-dependent patients compared with normal controls, have been reported in some previous studies. This study was designed to evaluate the prevalence rates of drug-use and other psychiatric disorders in the first-degree relatives of opiate-dependent patients and compare these with rates in the first-degree relatives of surgical and psychiatric patients. A case-control study was conducted to compare the prevalence of psychiatric and drug-use disorders (which were estimated by the Family History Method) in 241 biological first-degree relatives of 50 opiate-dependent patients to that in 235 and 222 first-degree relatives of 50 surgical and 50 psychiatric patients respectively. The main outcome measure was the relative risk (expressed as odds ratio) of psychiatric and drug-use disorders. First-degree relatives of opiate-dependent patients were found to have significantly higher rates of drug-use and antisocial personality disorders, compared with relatives of surgical and psychiatric probands. The odds ratio for alcoholism appeared significantly higher only in first-degree female relatives of opiate users, suggesting effect modification by sex. The study provides further evidence for the higher rate of drug-use disorder in the first-degree relatives of opiate-dependent patients. These findings suggest that familial drug-use disorder contributes to a vulnerability to opiate misuse. Implications of these findings for the classification and treatment of opiate dependence are discussed.