The latent structure of schizotypy: I. Premorbid indicators of a taxon of individuals at risk for schizophrenia-spectrum disorders.

A taxometric analysis (R. R. Golden & P. E. Meehl, 1979) was conducted to test the hypotheses that liability for schizophrenia-spectrum disorders is dichotomously distributed and that this liability can be detected premorbidly with behavioral indicators analogous to many of the criteria for schizotypal personality disorder. Behaviors were assessed in 207 offspring of schizophrenic mothers and 104 matched offspring of normal parents in 1962, when participants' mean age was 15 years. Diagnoses on the basis of the Diagnostic and Statistical Manual of Mental Disorders (3rd ed., rev.; American Psychiatric Association, 1987) were made in 1986-1989, when participants were nearly through the risk period for developing schizophrenia. The aggregation of indicators was consistent with a bimodal latent liability distribution. Membership in the schizotypal class was a sensitive and specific predictor of the emergence of schizophrenia-spectrum disorders in adulthood.