Psychosis and drug dependence: results from a national survey of prisoners

The links between drug use and psychosis are of major aetiological and prognostic significance. Psychosis and drug dependence frequently co-occur within the prison population, providing the opportunity to study this link more closely.

To explore the relationship between psychosis and drug dependence in a sample of prisoners.

A total of 3142 prisoners were surveyed nationally, and structured clinical data were obtained from a subsample of 503 respondents. Psychiatric assessment was based on the Schedules for Clinical Assessment in Neuropsychiatry (version 1.0). Measures of amphetamine, cannabis, cocaine and heroin use and dependence were obtained through self-report.

Logistic regression analyses indicated that first use of amphetamines or cocaine before the age of 16 years and severe cannabis or cocaine dependence were related to an increased risk of psychosis. In contrast, severe dependence on heroin was associated with a reduced risk of this classification.

Severe dependence on cannabis and psychostimulants is associated with a higher risk of psychosis and is in contrast to severe dependence on heroin, which has a negative relationship with psychosis.