Association of psychiatric and substance use disorder comorbidity with cocaine dependence severity and treatment utilization in cocaine-dependent individuals

The relations among psychiatric and substance dependence disorders and treatment utilization are of interest both for their clinical management and for health services. We examined these relations using six self-reported indices of cocaine dependence severity and three self-reported measures of treatment utilization and self-help group participation for cocaine dependence. The sample consisted of dyads: namely, a cocaine-dependent adult proband (N = 449) and a cocaine-dependent sibling (N = 449). Psychiatric and substance use disorders were assessed with the Semi-structured Assessment for Drug Dependence and Alcoholism. We controlled for the nesting within families of proband-sibling dyads and for demographic features using generalized estimating equation linear and logistic regression analyses. We found that psychiatric disorders were associated with an increased likelihood of cocaine dependence treatment or self-help group participation, but with only one of six indices of cocaine dependence severity. Bipolar disorder and antisocial personality disorder were associated with greater past heavy cocaine use, and with utilizing self-help but not treatment. Major depressive disorder and posttraumatic stress disorder were associated with treatment utilization and overall services utilization, respectively. The presence of other substance use disorders (SUDs) was the strongest correlate of cocaine dependence severity. Results suggest that co-occurring substance dependence and psychiatric disorders warrant attention in cocaine dependence assessment, treatment, and self-help.