Epidemiology of mental illness in a correctional system

Reports of higher than community rates of mental disorder in incarcerated populations first appeared in the mid-1970s. These findings have been confirmed over the past three decades in numerous studies across a wide spectrum of forensic settings. Recent research has benefited from enhanced methodological sophistication, and reliable rates across clinical domains and divergent forensic population groups are now available. This article reviews the literature on the prevalence of mental illness in forensic settings over the past 10 years, with special reference to specific subgroups.

Overall rates of any mental disorder, including personality disorder and addiction, remain high, in general ranging between 55% and 80%. The findings of recent, systematic surveys and of 22 studies reviewed here reveal rates of psychosis that are several times higher in correctional settings than in the community. Mood disorder rates are elevated also, with higher morbidity reported for women than for men. Findings in specialized populations indicate similarly elevated rates of mental disorder among adolescent and geriatric prisoners, while addiction rates rank highest across all population domains.

The prevalence of psychiatric illness in correctional settings is significantly elevated, with higher than community rates reported for most mental disorders. It is estimated that in the USA one in five incarcerated persons is afflicted with major psychiatric illness; with an estimated 9-10 million persons imprisoned worldwide, the burden of psychiatric illness in this vulnerable and marginalized population poses a serious challenge to researchers and clinicians alike.