Psychopathy and violent behavior among patients with schizophrenia or schizoaffective disorder

Although a strong association between violence and psychopathy has been demonstrated in nonpsychotic forensic populations, the relationship between psychopathy and violence among patients with schizophrenia has not been thoroughly explored. Patients with and without a history of persistent violent behavior were compared for comorbidity of psychopathy and schizophrenia or schizoaffective disorder.

Violent and nonviolent patients were identified through reviews of hospital charts and records of arrests and convictions. The Psychopathy Checklist: Screening Version was administered to 51 patients, 26 violent patients and 25 matched nonviolent patients. Analysis of variance was used as the principal statistical method for comparing violent and nonviolent groups.

Mean psychopathy scores were higher for violent patients than nonviolent patients. Five of the violent patients (19 percent) had scores exceeding the cutoff for psychopathy, and 13 (50 percent) scored in the possible psychopathic range. All of the nonviolent patients scored below the cutoff for possible psychopathy. Higher psychopathy scores were associated with earlier age of onset of illness and more arrests for both violent and nonviolent offenses.

The comorbidity of schizophrenia and psychopathy was found to be higher among violent patients than among nonviolent patients. Violent patients with schizophrenia who score high on measures of psychopathy may have a personality disorder that precedes the emergence of psychotic symptoms, or they may constitute a previously unclassified subtype of schizophrenia, characterized by early symptoms of conduct disorder symptoms and persistent violent behavior.