Associations of P50 suppression and desensitization with perceptual and cognitive features of "unreality" in schizotypy

Background: P50 suppression is an electrophysiologic index of early sensory gating and has consistently been found deficient in schizophrenic patients. This gating deficit is thought to lead to sensory overload and cognitive fragmentation, and correspondingly many symptoms of the disorder. However, the link between P50 suppression deficits and symptomatology is yet to be established, and so this study was designed to determine whether such a relation is present within a nonclinical population. Methods: P50 suppression and schizotypy measures were obtained from 36 healthy volunteers, and correlation analyses determined whether measures of schizotypy were related to P50 suppression. Results: Consistent with the view, that P50 gating deficits are related to schizophrenic symptoms, subjects with poorer P50 suppression reported more perceptual anomalies and magical ideation-an unreality syndrome-in contrast to other positive symptoms and to withdrawal. This study also found a trend to P50 suppression desensitization, and that whereas subjects low on "unreality" demonstrated desensitization to the second of the paired clicks, subjects high on "unreality" demonstrated sensitization. Conclusions: It is concluded that early sensory gating deficits, in the form of poor P50 suppression, are related to unreality aspects of schizotypy. This supports the view that poor P50 suppression in schizophrenia is related to symptomatology. Biol Psychiatry 2001;50:441-446 (C) 2001 Society of Biological Psychiatry.