Neurological soft signs in psychometrically identified schizotypy

Abstract

Patients with schizophrenia often exhibit structural brain abnormalities, as well as neurological soft signs (NSS), consistent with its conceptualization as a neurodevelopmental disorder. NSS are mild, presumably nonlocalizing, neurological impairments that are inferred from performance deficits in domains such as sensory integration, motor coordination, and motor sequencing. The vulnerability for schizophrenia is presumed to be expressed across a broad continuum of impairment referred to as schizotypy. It is hypothesized that nondisordered people along the schizotypy continuum should exhibit elevated rates of NSS. The present study examined the relation of psychometrically identified positive and negative schizotypy with NSS using the Neurological Evaluation Scale in a nonclinically ascertained sample of young adults (n=177). As hypothesized, negative, but not positive, schizotypy was related to increased NSS in tasks that assessed fine and gross motor coordination, motor sequencing, eye movement abnormalities, and memory recall. However, positive schizotypy was associated with increased NSS in tasks related to sensory integration dysfunction. In general, the positive×negative schizotypy interaction term was unrelated to individual NSS tasks. The findings support: a) the theory that the vulnerability for schizophrenia is expressed across a broad continuum of subclinical and clinical impairment referred to as schizotypy; b) the multidimensional structure of schizotypy; and c) the notion that schizotypy is an appropriate construct for understanding the etiology and development of schizophrenia-spectrum disorders.