Lecture: Epidemiology and forensic psychiatry*

Abstract

Epidemiology has been oustandingly successful in assisting with the understanding and prevention of disease. This is as true in psychiatry as in general medicine. It is also true in forensic psychiatry, for example in understanding the relationship between homicide and psychosis, the development of antisocial personality disorder and the causation of crime. Philippe Pinel advocated scientific enquiry as part of humanitarian psychiatry. The Institute of Psychiatry in London has used epidemiology for research in forensic psychiatry, for example in determining the prevalence of mental disorders, including epilepsy, in prisons, the relationships between violence and disease and the outcome of patients deemed unfit to plead. Epidemiological findings need careful interpretation, for example Penrose’s Law is an invalid myth that has arisen from a misunderstanding of epidemiological data. Recent surveys of prisoners have confirmed that substance abuse and personality disorder are the most common psychiatric diagnoses among prisoners, only 1‐2% being psychotic. About 4% of prisoners (700 or 800) should be transferred into NHS psychiatric hospitals. These findings could be useful to planners.