Mood and Personality Disorders Research Program

Schizotypal Personality Disorder

Overview

Although schizotypal personality disorder shares an extensive array of similarities with schizophrenia in terms of genetics, phenomenology, neurochemistry, structural anatomy, and functional anatomy, patients with schizotypal personality disorder are spared overt psychotic symptoms and have less severe cognitive disturbances than patients with schizophrenia. Several possibilities may be hypothesized regarding the relationship between schizotypal personality disorder and schizophrenia. One is that schizophrenia and schizotypal personality disorders are truly distinct and only have superficial similarities. This hypothesis is unlikely given the common genetic factors shared between the two disorders, but could still apply to many schizotypal personality disorder subjects drawn from clinical or volunteer populations. While difficult to disprove definitively, this hypothesis would imply that an in-depth examination of genetic susceptibility factors, structural and functional neuroanatomy, and cognitive impairment would yield distinct differences and few similarities in the patterns of abnormalities of subjects with the schizotypal and schizophrenia disorders. A second hypothesis is that the two disorders are identical and differ only in severity, predicting that specific abnormalities in these domains would be identical in character and differ only in the extent of the abnormality. Finally, a third hypothesis posits that the disorders are partially overlapping in etiology and genetics with both similarities, i.e., common risk or susceptibility factors that they share as part of the schizophrenia spectrum and differences, that account for the sparing of schizotypal patients from frank psychosis and cognitive deterioration.

If this third hypothesis proves true, a better understanding of these differences would enable us to approach schizotypal personality disorder as an experiment of nature, and an opportunity to better understand the basis of psychosis and the cognitive impairments of schizophrenia can be afforded. It may also help us to disentangle the contributions of genetic and environmental factors in the development of schizophrenia. Recent findings of neurobiological differences between schizotypal personality disorder and schizophrenia are beginning to suggest specific factors that may be protective against overt psychotic symptoms in the schizophrenia spectrum and that explain the more circumscribed cognitive impairments in schizotypal personality disorder... These differences provide important clues to risk for "core" cognitive and social deficits and protective factors against psychosis and severe functional deterioration in the schizophrenia spectrum.

From: Larry J. Siever, Harold W. Koenigsberg, Philip Harvey, Vivian Mitropoulou, Marc Laruelle, Anissa Abi-Dargham, Marianne Goodman and Monte Buchsbaum, Cognitive and brain function in schizotypal personality disorder, Schizophrenia Research, Volume 54, Issues 1-2, 1 March 2002, Pages 157-167.