Illicit Drug Use in Oneʹs Social Network and in Oneʹs Neighborhood Predicts Individual Heroin and Cocaine Use

PURPOSE: The nature of competing social environmental factorsʹ influence on substance abuse is unclear. A longitudinal study was undertaken to determine the relative power of social network and neighborhood characteristics to predict continuing illicit drug use. METHODS: Three hundred forty-two inner-city adults with a history of injection drug use were followed for 1 year; their heroin and cocaine use were assessed semiannually. Multiple logistic regression models were fit to determine the degree to which social network and neighborhood characteristics, assessed at baseline, predicted continuing heroin and/or cocaine use throughout the study period. RESULTS: Two hundred thirty-six (69%) participants reported continuing heroin and/or cocaine use. Drug use by members of the social network was a stronger predictor of participantsʹ continuing drug use (OR = 4.31, 95% CI 2.51 to 7.40) than was a high level of drug-related arrests in the participantʹs neighborhood (OR = 2.41, 95% CI 1.24 to 4.71), after adjusting for drug treatment and demographic variables. Both seemed to have independent effects on study participantsʹ drug use. CONCLUSIONS: These findings reiterate the importance of breaking ties with drug-using associates, even for those who reside in high-risk environments. Further work is needed to develop interventions that increase drug usersʹ success in altering social network composition or also treat drug-using network members.