Consumption of psychoactive substances in prison: Between initiation and improvement, what trajectories occur after incarceration? COSMOS study data (2019)

Background: Few studies have examined the consumption trajectories of inmates after entry to prison. The aim of this study was to assess the changes in the consumption of psychoactive substance between the period before detention and during incarceration and to characterize the profiles of prisoners with similar consumption trajectories during incarceration.
Methods and findings: A multicenter, cross-sectional study was performed in all of the prisons from one region of France. All prisoners incarcerated during their 3rd months, over 18 years old, and with a sufficient level of French fluency to participate in the study were recruited over a period of 12 months. A total of 800 prisoners were recruited. All prisoners were interviewed face-to-face by a trained interviewer. A majority of prisoners had used at least one psychoactive substance in the weeks prior to incarceration. During incarceration, a substantial reduction in alcohol and illicit drug consumption was observed. The initiation of consumption and an increase in consumption were primarily related to medications. Five different profiles of consumption before incarceration were identified. These profiles all had a high probability of migrating to a similar profile during detention, characterized by less severe consumption of psychoactive substances.
Conclusions: Based on their consumption profile prior to incarceration, most prisoners would benefit from a specific medical evaluation as soon as possible following entry into detention. Prison could be an opportunity for reduced consumption and/or the initiation of treatment for the majority of prisoners, despite the pejorative development observed for a minority of prisoners during incarceration.