Individual predictors of the subjective effects of intravenous cocaine.

The subjective and reinforcing effects of addictive substances can vary greatly between individuals. This study compared the relative contributions of baseline drug use, craving, stressful life events, and social factors in determining the subjective effects of cocaine in individual participants. Twelve veterans meeting criteria for cocaine dependence were evaluated in a laboratory setting. Self-report of the subjective effects of intravenous cocaine was recorded following single- and double-blind, placebo-controlled injections. Increased positive subjective effects of cocaine, including drug-induced 'good' effects and the value of intravenous injections, were most strongly correlated with greater family and social dysfunction measured through the Addiction Severity Index (ASI). Social dysfunction was the strongest predictor of cocaine-induced euphoria, accounting for approximately one-half of its variability. Participants who were dissatisfied with their current marital status reported almost no 'bad' effects of cocaine but instead reported increased drug-induced 'high', euphoria, and injection value. Although further research is required to determine the generalizability of this association, our findings are parallel to recent preclinical results showing that social interaction can attenuate psychostimulant reward. Effects of substance abuse treatment that rely on improved social function may be mediated through changes in the brain's reinforcement system that modify the rewarding effects of cocaine.