Effect of risperidone on prepulse inhibition of the startle reflex and P50 deficit in patients with first-episode and chronic schizophrenia

Abstract

Objective: To investigate the effect of antipsychotic medicine risperidone on prepulse inhibition of the startle reflex (PPI) and P50 deficit in patients with first-episode and chronic. Methods: Thirty-eight patients with first-episode schizophrenia and 36 patients with chronic schizophrenia, both in acute stage, were enrolled in the study. All patients were treated with risperidone of different doses (2 to 6mg/d). All patients fulfilled the evaluation of PPI and P50 before treatment and 8 weeks after treatment. The psychotic symptoms were assessed with Positive and Negative Syndrome Scale (PANSS), and the therapeutic effects were evaluated with PANSS reduction rate. Results: (1) There was no significant difference in PPI and P50 parameters between the two groups before treatment (PPI ratio: first group 43%±29%, chronic group 42%±27%, P>0.05; P50 S2/S1 ratio: first group 83%±33%, chronic group 82%±24%, P>0.05). (2) There was no significant correlation between PPI and P50 inhibition parameters and disease course, psychotic episodes and psychiatric symptoms (PANSS total score, positive symptoms score, negative symptoms score and general psychopathology symptoms score) of schizophrenia (P>0.05). (3) Except the group main effect for S2 amplitude (F=5.75, P=0.019), there was no significant change for main effect and interaction of the other P50 and PPI inhibition ratio parameters after treatment (P50 S2/S1 ratio: first group before treatment 83%±33%, after treatment 85%±49%, P>0.05; chronic group before treatment 82%±44%, after treatment 84%±35%, P>0.05. PPI ratio: first group before treatment 43%±29%, after treatment 42%±27%; chronic group before treatment 42%±27%, after treatment 41%±28%,P>0.05). The effect of risperidone on P50 and PPI parameters was not related to the therapeutic effect. Conclusion: Deficit in sensory gating inhibition exists in both first-episode schizophrenia and chronic schizophrenia, and risperidone is not effective in treating the deficit in sensory gating (PPI and P50) inhibition of schizophrenia.