Does the pattern of amphetamine use prior to incarceration predict later psychosis?--a longitudinal study of amphetamine users in the Swedish criminal justice system

Abstract

Objectives: The aim of this longitudinal study was to investigate the relationship between self-reported amphetamine use prior to inclusion in the criminal justice system and hospitalization due to psychosis in the years following release.

Method: All the information was extracted from existing databases. Amphetamine-using clients in the criminal justice system in Sweden were identified using the European version of the addiction severity index (Europ-ASI) interview. Between 2001 and 2006, a total of 1709 individuals were identified. A follow-up of the subjects, using national registry data, was conducted in 2010. The outcome measure was hospitalization for primary or substance-induced psychotic episodes during the follow-up period. Data was analyzed in a multivariate logistic regression model.

Results: Age of onset of amphetamine use, number of years used, and use in the month prior to baseline interview were all unrelated to risk of future hospitalization due to psychosis. Prior psychiatric hospitalization and experience of hallucinations not related to drug use, as well as being born outside of a Nordic country and being homeless, were all positively linked to hospitalization due to psychosis.

Conclusions: This study demonstrates that, in a cohort of amphetamine users within the criminal justice system, prior psychiatric morbidity and demographic risk factors are more important than baseline patterns of amphetamine use in predicting future risk of hospitalization due to psychosis.

Keywords: Amphetamine; Methamphetamine; Prison; Psychosis; Schizophrenia.