507. Schizophrenia patients and normal controls demonstrate a similar effect of sex on prepulse inhibition of the startle reflex

Abstract

Prepulse inhibition (PPI) of the startle response is an operational measure of sensorimotor gating that is impaired in schizophrenia patients, whose PPI deficits correlate with thought disorder and distractibility. Normal control males have greater PPI than normal females. We investigated the effects of gender on PPI and other startle measures in schizophrenia and control participants with the goal of examining whether the effect of schizophrenia on sensorimotor gating interacts with the effect of gender. Fifty-two schizophrenia patients (25 female) and fifty-seven normal controls (26 female) participated in a startle reflex testing session. Overall, schizophrenia patients demonstrated less PPI than normal subjects and men showed more PPI than women. There was no interaction between gender and group. Additionally, schizophrenia patients demonstrated less habituation of startle than controls, but there was no significant effect of gender and no gender by group interaction on habituation. There were no significant effects of gender or group on the overall amplitude of the startle reflex, but women demonstrated a faster peak latency than men, and controls demonstrated a trend toward faster responses than patients (p = .056). This study of 109 subjects demonstrates that: 1) Schizophrenia patients have deficient PPI regardless of gender effects. 2) Males have greater PPI than females, and this is true for both schizophrenia patients and normal control subjects. 3) Although female schizophrenia patients have decreased PPI attributable to both gender and diagnosis, their “milder” form of clinical impairment may relate to the process of cyclical modulation of PPI by sex hormones. This hypothesis relates to dynamical theories of complex dysregulation verses hypotheses of fixed deficits of brain functions and will be discussed in detail.