P50 auditory sensory gating in first onset schizophrenics and normal healthy adults.

The aim of this research was to investigate the variations of P50 auditory sensory gating (P50) in normal healthy adults and the first onset schizophrenics. By using the American Nicolet Bravo electromyography/evoked potential (EMG/EP) system, P50 was measured with conditioning-testing paradigm (paired-click stimuli S1 and S2 were used) in 58 first onset schizophrenics and 108 healthy adults, and the Positive and Negative Syndrome Scale (PANSS) was applied. The following three conclusions have been reached. (1) In normal control (NC) group, measured from central, anterior and posterior zone (Cz, Fz and Pz respectively), there were no statistical differences (P > 0.05) between S1 and S2 evoked P50 peak latencies (S1-P50 and S2-P50); the amplitudes of S2-P50 [(2.2 ± 1.4), (2.3 ± 1.5) and (2.1 ± 1.4) μV respectively] reduced significantly as compared with S1-P50 [(5.6 ± 3.3), (5.6 ± 3.9) and (4.9 ± 2.8) μV respectively] (P < 0.01); the S2/S1 ration, S1-S2 difference, and 100 (1-S2/S1) had no statistical differences (P > 0.05). (2) Compared with NC, the schizophrenic group significantly showed lower S1-P50 amplitudes (P < 0.01, except at Pz in which Z = 2.030, P = 0.042), higher S2-P50 amplitudes, higher S2/S1 ratio, lower S1-S2 difference, and more decreased 100 (1-S2/S1) (P < 0.01) at Cz, Fz and Pz. (3) No significant correlations were found among S2/S1 ratio, S1-S2, 100 (1-S2/S1) of sensory gating and PANSS (P > 0.05) in schizophrenic group. The first onset schizophrenics had sensory gating deficits, which could be quantified by P50.