Pattern of P50 suppression deficit in patients with epilepsy and individuals with schizophrenia.

OBJECTIVE To identify P50 suppression in patients with epilepsy, to investigate the effect of seizure control on P50 suppression, and to compare epilepsy patients with individuals with schizophrenia and healthy volunteers. METHOD P50 evoked potential parameters and P50 suppression were studied crossectionally in patients with uncontrolled or controlled epilepsy, in individuals with schizophrenia and in healthy volunteers. RESULTS Individuals with schizophrenia had significantly smaller conditioning stimulus (S1) amplitude, and patients with epilepsy had larger test stimulus (S2) amplitude. Mean S2/S1 ratio was 0.71 ± 0.33 for patients with uncontrolled epilepsy; 0.68 ± 0.36 for patients with controlled epilepsy; 0.96 ± 0.47 for individuals with schizophrenia, and 0.42 ± 0.24 for healthy volunteers. CONCLUSION The sensory filter of patients with epilepsy is altered, and this alteration is not associated with seizure control. Also, it works differently from the sensory filter of individuals with schizophrenia.