Patients were classified into violent and non-violent in accordance to the Overt Aggression Scale. P50 auditory evoked potentials of 32 unmedicated patients with schizophrenia (violent = 14, non-violent = 18) and 17 healthy controls were recorded during five runs of 30 click pairs.
Healthy controls exhibited a lower S2/S1 ratio when compared to violent (p < 0.001) and non-violent (p = 0.04) patients. Using a cutoff point of 0.50 for S2/S1 ratio to define abnormal gating a significant proportion of violent patients did not show P50 suppression (71.4%) in comparison to non-violent patients (38.9%) and healthy controls (23.5%) (p = 0.02).
Violent behavior in patients with schizophrenia could be associated with a disturbed information sensory gating. Violence in patients with schizophrenia may be facilitated by an increased arousal which may in turn be the result of an information-processing deficit.