Prevalence of serious mental illness among jail inmates

This study estimated current prevalence rates of serious mental illness among adult male and female inmates in five jails during two time periods (four jails in each period).

During two data collection phases (2002-2003 and 2005-2006), recently admitted inmates at two jails in Maryland and three jails in New York were selected to receive the Structured Clinical Interview for DSM-IV (SCID). Selection was based on systematic sampling of data from a brief screen for symptoms of mental illness that was used at admission for all inmates. The SCID was administered to a total of 822 inmates-358 during phase I and 464 during phase II. To determine the current (past-month) prevalence of serious mental illness (defined as major depressive disorder; depressive disorder not otherwise specified; bipolar disorder I, II, and not otherwise specified; schizophrenia spectrum disorder; schizoaffective disorder; schizophreniform disorder; brief psychotic disorder; delusional disorder; and psychotic disorder not otherwise specified), interview data were weighted against strata constructed from the screening samples for male and female inmates by jail and study phase.

Across jails and study phases the rate of current serious mental illness for male inmates was 14.5% (asymmetric 95% confidence interval [CI]=11.0%-18.9%) and for female inmates it was 31.0% (asymmetric CI=21.7%-42.1%).

The estimates in this study have profound implications in terms of resource allocation for treatment in jails and in community-based settings for individuals with mental illness who are involved in the justice system.