Sexually dimorphic deficits of prepulse inhibition in patients with major depressive disorder and their relationship to symptoms: A large single ethnicity study.

Background: Sensorimotor gating deficits as measured by prepulse inhibition (PPI) of acoustic startle reflex have been repeatedly observed in patients with schizophrenia. However, studies investigating PPI in patients with major depressive disorder (MDD) are scarce, and this issue remains to be elucidated.

Methods: Subjects were 221 patients with MDD and 250 age-matched healthy comparison subjects. Depressive symptoms were assessed by the 21-item version of the Hamilton Depression Rating Scale (HAM-D21), and the scores were divided into six factors. Thirty-five trials of startle reflex to pulse alone and pulse with prepulse were measured by electromyography. Startle magnitude, habituation, and PPI were compared between patients and comparisons stratified by sex. Relationships of startle measures to symptoms and antidepressant medication were assessed.

Results: Male patients showed significantly reduced PPI compared to male comparisons, while no significant PPI difference was found between female patients and comparisons. HAM-D21 total score and several subscales were significantly correlated with PPI only in male patients. The effect of antidepressant medication was not significant for either male or female patients.

Limitations: Possible effects of the menstrual cycle could not be excluded among female subjects.

Conclusions: These findings suggest that male patients with MDD show sensorimotor gating deficits in a state-dependent manner. However, we obtained no evidence for such abnormalities in female patients with MDD.