Motor dysfunction and risk for schizophrenia.

Motor dysfunction is associated with schizophrenia, and recent longitudinal studies indicate that it precedes the onset of clinical symptoms. Of particular interest is the heightened occurrence of involuntary movements, which are apparent as early as infancy and suggest the presence of subcortical brain abnormalities. In this article, we present the results of a study of spontaneous movements in adolescents with schizotypal personality disorder (SPD). SPD is a syndrome that has been shown to be genetically linked with schizophrenia and is often observed prior to the early adult onset of schizophrenia. Systematic coding of videotapes of diagnostic interviews revealed that the SPD group showed significantly more involuntary movements of the head, trunk, and upper limbs than did normals and adolescents with other personality disorders. There were no diagnostic group differences in the rate of voluntary movements. Salivary cortisol, measured before the interview, was positively correlated with involuntary movements. Taken together, the findings provide further support for the hypothesized etiologic relation between SPD and schizophrenia. Based on a neural diathesis-stress model, potential underlying mechanisms are discussed.