A preliminary study of acoustic startle reflex in male patients with chronic schizophrenia

Abstract

Objective To explore the deficits of acoustic startle reflex (ASR) that might exist in Chinese patients with schizophrenia and the effects of antipsychotics on ASR. Methods Participants included 25 male patients with chronic schizophrenia treated with typical antipsychotics ( typical group), 25 with atypical antipsychotic clozapine (clozapine group) and 25 healthy male subjects (control group)matched for age and years of education. Startle reflex to acoustic stimuli were examined in all subjects from the three groups. At the same day of startle testing, psychopathological symptoms of the patients were assessed with the Positive and Negative Syndrome Scale (PANSS). Results (1) Startle response(SR) was significantly reduced in typical group than in control group[ (553.6 ±516. 9) mV vs (942. 0 ±447. 3) mV,P =0. 009]. SR of clozapine group [ (755.9 ±439. 4) mV] was greater than that of typical group and less than that of control group, but there was no significant difference between clozapine group and the other two ( P ＞ 0. 05 ). (2) Habituation (HAB) of startle reflex in typical group was significantly lower than in control group [ ( 17. 8 ± 35. 8 ) % vs (44. 9 ± 28.9) %, P = 0. 027 ]. HAB of clozapine group [ (22. 9 ± 34. 1 ) % ]was higher than that of typical group and less than that of control group, but there was no significant difference between clozapine group and the other groups ( P ＞ 0. 05 ). ( 3 ) Compared with healthy controls,patients of typical group exhibited the significant reduction in prepulse inhibition (PPI) of startle reflex (P = 0. 024) when prepulse interval (LI) was 120 ms. PPI of clozapine group was higher than typical group and less than control group, but no significant differences in PPI were found between clozapine group and the other groups. While LI was 30 ms or 120 ms, PPI among the three groups did not show significantly different (P ＞ 0. 05 ). (4) No significant relationship was found between PPI of different LIs and symptom scores assessed with PANSS in patients with schizophrenia ( P ＞ 0. 05 ) . Conclusions Our findings suggest impaired PPI in Chinese patients with schizophrenia. Atypical antipsychotic clozapine might partly improve disinhibition of startle reflex in schizophrenic patients. Key words: Schizophrenia; Startle reaction; Prepulse inhibition