Habituation of the blink reflex in first-episode schizophrenia, psychotic depression and non-psychotic depression

Objective: Electrophysiological recording of the electrically elicited blin k reflex is the most reliable method of investigating habituation of the st artle reflex. The purpose of this study was to compare the habituation and the late R3-component of the blink reflex between control subjects (N = 19) and first-episode patients with schizophrenia (N = 17), psychotic depressi on (N = 23), and severe non-psychotic depression (N = 25). Methods: The bli nk reflex was evoked by electrical stimulation of the supraorbital nerve, a nd the deficient habituation of the R2i-component was measured with a compu ter-assisted integral area measurement. Prefrontal executive function of th e patients was assessed with the Wisconsin Card Sorting Test. Current psych iatric symptoms were assessed with the Brief Psychiatric Rating Scale, the Hamilton Depression Scale, the Positive and Negative Syndrome Scale, and th e Calgary Depression Scale. Results: Deficient habituation of the blink ref lex and occurrence of the late R3 component were associated both with a pre vious diagnosis of psychotic disorder and with the presence of current psyc hosis. The sensitivity and specificity of the abnormal habituation of the b link reflex in detecting psychotic disorder were 0.50 and 0.80, respectivel y. The abnormalities of the blink reflex were not associated with psychotro pic medication. In schizophrenic patients, defective habituation of the bli nk reflex was associated with negative and cognitive symptoms, and in depre ssive patients with the presence of delusions. Conclusions: The deficient h abituation of the blink reflex and occurrence of the late R3 component seem to be both trait and state markers of a psychotic disorder. The results su ggest that schizophrenia and psychotic depression share some common neurobi ological mechanisms involved in the modulation of the startle reflex. (C) 2 000 Elsevier Science B.V. FLU rights reserved.