Objective. To study the characteristics of the early stages of sensory (inhibition of the P50 event-related potential) and sensorimotor (prestimulus modification of the acoustic startle reaction (ASR)) information processing in patients with schizophrenia taking account of their behavioral characteristics. Materials and methods. Two groups of patients were investigated using oculography and electroencephalography: aggressive patients (group A, 44 subjects) and nonaggressive patients (group NA, 27 subjects); a control group of 48 healthy subjects were also studied. Patients' mental status was assessed on the PANSS. Results and conclusions. These studies identified features characteristic of schizophrenia patients, particularly increases in the latent period of ASR, deficiency of prestimulus inhibition (PSI) (with delay intervals of 60 msec), and inhibition of P50 relative to normal. The aggressivity factor influenced the lateralized features of these deviations in ASR only in group A. Group NA showed an increase in baseline ASR amplitude and a decrease in prestimulus ASR amplitude. Analysis of P50 showed a significant increase in amplitude and a decrease in latency in responses to the second stimulus in group NA. A significant increase on the G14 scale (Poor impulse control) and the nature of its correlation with ASR and P50 measures in group A suggested that increased impulsivity was an important factor in aggressive behavior in the cohort of patients studied here. The characteristics of ASR and P50 typical of group NA provided evidence of increased sensitivity to external stimuli, which may be associated with personality features inhibiting aggression. These results led to the conclusion that measures of the earl y stages of information processing can be regarded as potential predictors of aggressive behavior in schizophrenia patients.
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