The relationship between mental disorders and different types of crime

Background Previous studies of relationships between mental disorder and crime have tended to group the mental disorders, the crimes or both, leaving uncertainty about a more specific mental disorder: crime relationships.Objective To examine the relationship between types of mental disorder and types of crime in pre-trial defendants.Method Data were extracted from 21,424 pre-trial forensic psychiatric reports made between 2000 and 2006 in the Netherlands. We compared the prevalence of axis I disorders, personality disorders, intellectual functioning and substance abuse in defendants charged with a range of crimes (homicide, attempted/threatened homicide, assault, battery, rape, sexual crimes, arson and/or property crimes) using chi-square tests. Relationships with diminished accountability, reflecting a direct relationship with underlying mental disorder, were calculated using multivariate regression models, adjusted for age, gender, ethnicity and history of judicial contact.Results Arson had the strongest relationship with mental disorders in our sample, then assaults, then homicidal attempts or threats. Sexual and property crimes had the weakest relationship with diminished or absent accountability. Diminished accountability had the strongest relationship with psychotic disorders, followed by organic psychosyndromes and developmental disorders, whereas other axis I disorders, personality disorders or an IQ score of <85 points were only moderately related. These relationships varied little according to the type of crime, although tended to be weaker for defendants in property crimes. Cannabis and hard drugs were significantly associated with decreased accountability only in respect of arson.Discussion Mental disorders are related to all types of crimes but especially to arson, battery and homicidal attempts or threats, with a court finding of diminished accountability providing some validation for perceived links between the disorder and crime in this study.