Schizophrenia and violence: Epidemiological, forensic and clinical aspects

Recent studies confirm a significantly (several times, in fact) increased risk for schizophrenics to commit severely violent acts compared to the general population. Violent acts of minor degree and threats not followed by forensic detention are even much more common. Data on prevalence depend on study conditions, sample selection, and outcome definitions of violence. In psychiatric hospitals, too, violent and threatening behaviour seems to occur most frequently in schizophrenic patients. However, in this respect findings are inconsistent and display considerable variations across different countries and times (with increasing rates reported within the last decade). Additional risk indicators beside the diagnosis of schizophrenia are male gender, comorbidity with personality disorders, substance abuse, lack of adequate treatment and increasing social disintegration due to an unfavourable course of the illness. The violence risk does not seem to decrease with increasing age in contrast to the general population. Beyond these sociodemographic data and variables related to treatment and course of illness, psychopathological causes of violence are less evident. Even imperative hallucinations are not clearly associated with violence; systematic delusions are associated with severe violent acts, but not with the much more frequent violent acts of minor degree. Most probably, the total of psychopathological symptomatology is associated with the proneness to aggressive behaviour. Neuropsychological and biological findings are also inconsistent.