Changes in the social networks of heroin and cocaine users after quitting

Research has shown a relationship between an individuals' substance use and the substance use of their social network members. Competing theories posit that an individual uses drugs due to influences from drug-using peers (Differential Association), that individuals who have poor bonding to conventional society use drugs and consequently spend time with drug-using individuals (Social Control), or both (Interactional). The present study examines the social networks of drug users after quitting with data from 636 individuals who used cocaine or heroin in the past year at baseline. Individuals were “quitters” if they had no heroin or cocaine use in the past 6 months at time 2 (9 months later). At baseline, 94% of those who would later quit and 95% of those that did not quit had at least one current drug user among their social network members. At time 2, the proportion dropped to 58% for quitters and 90% for non-quitters. The differences in these proportions over time between quitters and non-quitters were tested in a logistic regression model, using Generalized Estimating Equations to handle the repeated measures. The model indicated that both groups had a significant decline between times 1 and 2 (OR = 0.4, 95% CI: 0.3-0.7), and the decline was significantly greater for those who quit their drug use by time 2 than for non-quitters (by an interaction term; OR = 0.2, 95% CI: 0.1-0.5). The model also included age, sex, and education. The findings support social control processes and have implications for drug treatment.