Availability of drugs and psychological proneness in opioid addiction.

The role of drug availability and psychological proneness in opioid addiction was examined using longitudinal data from the Drug Abuse Reporting Program (DARP). The sample included 424 addicts who were followed up and interviewed approximately 12 years after admission to treatment in the DARP, and for whom admission, during-treatment, and 6-year follow-up data were also available. Drug availability and proneness were both found to be important for drug use at any given time--from initial stages of addiction as well as in Year 12 of the follow-up--but proneness was rated as relatively more important for opioid use in the later stages of the addiction career. Proneness measures contributed more to the prediction of long-term drug use outcomes.