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

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.