FAMILIAL TRANSMISSION OF SUBSTANCE USE DISORDERS

Background: There is increasing evidence that substance use disorders are familial and that genetic factors explain a substantial degree of their familial aggregation. To perform a controlled family study of pr obands with several different predominant drugs of abuse, including op ioids, cocaine, cannabis, and/or alcohol. Methods: The subjects for th e present study included 231 probands with dependence on opioids, coca ine, cannabis, and/or alcohol and 61 control probands, and their 1267 adult first-degree relatives. Diagnostic estimates were based on semis tructured diagnostic interviews and/or structured family history inter views regarding each proband, spouse, and adult first-degree relative, The interview data were reviewed blindly and independently by clinici ans with extensive experience in the evaluation and treatment of subst ance use disorders. Results: There was an 8-fold increased risk of dru g disorders among the relatives of probands with drug disorders across a wide range of specific substances, including opioids, cocaine, cann abis, and alcohol, which is largely independent from the familial aggr egation of both alcoholism and antisocial personality disorder. There was also evidence of specificity of familial aggregation of the predom inant drug of abuse. Conclusions: Elevation in risk of this magnitude places a family history of drug disorder as one of the most potent ris k factors for the development of drug disorders. These results suggest that there may be risk factors that are specific to particular classe s of drugs as well as risk factors that underlie substance disorders i n general.