[The follow-up study on P50 auditory sensory gating in naïve schizophrenia]

To understand the variations of sensory gating P50 in naïve schizophrenia during follow-up and the relations with positive and negative symptom scale (PANSS).

The data of auditory evoked potential P50 were recorded by USA Nicolet Brova instrument from 58 naïve schizophrenia patients (Sch) and 108 normal controls (NC) at baseline, Months 1, 2 and 3 after treatment. And a simultaneous assessment of PANSS was made.

(1) At baseline, as compared with NC, Sch group had a sensory gating deficit, reflected by a higher S2/S1 (Cz: NC: 0.43 (0.27, 0.58); Sch: 0.77 (0.58, 1.04); Z = -9.23, P < 0.01), lower S1-S2 (Cz: NC: 2.65 (1.55, 4.79) microV; Sch: 0.92(-0.13, 2.32) microV; Z = -6.01, P < 0.01) and decreased more (1-S2/S1) (Cz: NC: 0.57 (0.43, 0.73); Sch: 0.23 (-0.04, 0.42); Z = -10.61, P < 0.01). (2) During follow-up, Sch group still had a sensory gating deficit. Compared with NC, Sch group had a more elevated S2-P50 amplitude, higher S2/S1, lower S1-S2 and (1-S2/S1) at Cz, Fz and Pz brain sites (P < 0.05 - 0.01), and no significantly differences with S2-P50 amplitude, S2/S1, S1-S2 and (1-S2/S1) during follow-up (P > 0.05). At baseline, Sch group had a much lowered S1-P50 amplitude than NC group at Cz and Fz brain sites (Cz: Sch: 4.1 microV +/- 2.1 microV, NC: 5.6 microV +/- 3.3 microV, t = -1.47, P = 0.001; Fz: Sch: 3.9 microV +/- 2.1 microV, NC: 5.6 microV +/- 3.9 microV, t = -1.63, P = 0.003). At Month 3, Sch group showed an improved S1-P50 amplitude to normal level at Cz brain site, but S1-P50 amplitude improved at Fz brain site but it was lower than NC group (Sch: 3.9 microV +/- 1.9 microV, NC: 5.6 microV +/- 3.9 microV, t = -1.62, P = 0.03). (3) At Month 3, Sch group showed a much lowered PANSS scale, positive symptom scale, negative symptom scale and general psychiatric symptoms scale than that at baseline (baseline: 138 +/- 15, 33 +/- 7, 41 +/- 5, 65 +/- 8; Month 3: 80 +/- 15, 17 +/- 4, 24 +/- 4, 38 +/- 9 respectively, P < 0.01). Spearman correlation revealed that P50 was not correlated with PANSS at baseline (P > 0.05). After treatment S2/S1 and (1-S2/S1) correlated with positive symptom scale and thought disorder and S1-S2 positively with thought disorder in schizophrenia (P < 0.05).

Sensory gating deficit is closely related with thought disorder in naïve schizophrenia. And it may be an important pathogenesis of naïve schizophrenia. P50 sensory gating deficit is probably a diathesis marker in schizophrenia.