RESUMO
OBJECTIVE: To investigate the change of sensory gating P50 in schizophrenic patients with and without homicide. METHODS: The auditory evoked potentials P50 were recorded from 26 schizophrenic patients with homicide (Sch group), 27 schizophrenic patients without homicide (non-Sch group) and 32 normal controls (NC) using conditioning/testing paradigm presented with auditory double click stimuli by EGI 256 dense array. And the same time, their clinical symptoms were evaluated by positive and negative symptom scale (PANSS). RESULTS: (1) Compared with NC, two Sch groups showed no significant difference in amplitude and latency of S1-P50 [amplitude: NC, Sch group, non-Sch group at Fz: (2.4 + or - 1.6) microV, (2.5 + or - 1.5) microV, (3.4 + or - 2.7) microV; latency: NC, Sch group, non-Sch group at Fz: (68 + or - 19) ms, (67 + or - 20) ms, (61 + or - 19) ms; respectively], but a higher amplitude and delayed latency of S2-P50 [amplitude: NC, Sch group, non-Sch group at Fz: (0.8 + or - 0.7) microV, (2.5 + or - 1.6) microV, (3.3 + or - 2.2) microV; latency: NC, Sch group, non-Sch group at Fz: (50 + or - 26) ms, (75 + or - 19) ms and (70 + or - 24) ms respectively] (P < 0.01), and no significant difference in amplitude and latency of S2-P50 between two Sch groups. (2) Compared with NC, two Sch groups showed a higher S2/S1 ratio [NC, Sch group, non-Sch group at Fz: 35 + or - 26, 153 + or - 137, 125 + or - 85, respectively], lower S2-S1 [NC, Sch group, non Sch group at Fz: 1.69 + or - 1.55, 0.08 + or - 2.41 and 0.17 + or - 2.30, respectively] and 100 (1-S2/S1) [NC, Sch group, non-Sch group at Fz: 65 + or - 26, -53 + or - 137 and -25 + or - 85 respectively] (P < 0.01). And there was no significant difference in S2/S1 ratio, S2-S1 and 100 (1-S2/S1) between two Sch groups. (3) Two Sch groups showed no significant difference in PANSS total, P scale, N scale, and G scale [Sch group: (110 + or - 27), (26 + or - 10), (29 + or - 7), (55 + or - 12); non Sch group: (105 + or - 27), (24 + or - 8), (28 + or - 10) and (53 + or - 12) respectively] (P > 0.05), and no significant correlation with S2/S1 ratio, S2-S1 and 100(1-S2/S1) (P > 0.05). CONCLUSION: Sensory gating deficit exists in schizophrenic patients with and without homicide. And it can be quantified by measuring auditory evoked potential P50, but sensory gating P50 has no difference between schizophrenic patients with and without homicide.