Objective: This study was designed to investigate the association between major mental disorders (MMDs) and homicide.
Method: The rates of exculpations because of MMDs among 1087 Austrian homicide offenders during 1975 and 1999 were compared with the rates of the respective disorders in the general population.
Results: MMDs were associated with an increased likelihood of homicide (two-fold in men and six-fold in women). This was exclusively because of schizophrenia (age-adjusted ORs in men 5.85, CI 4.29-8.01; in women 18.38, CI 11.24-31.55) and delusional disorder in men (OR 5.98, CI 1.91-16.51). Comorbid alcohol abuse/dependence (additionally) increased the odds in schizophrenia, major depression and bipolar disorder.
Conclusion: The increased likelihood of homicide in subjects with MMDs cannot be fully explained by comorbid alcoholism. The results point to the special importance of sufficient treatment for a subgroup of mentally ill individuals being at higher risk of violence.