An Evaluation of the Structure of Schizophrenia Spectrum Personality Disorders

Research into the genetics of schizophrenia has revealed the importance of a spectrum of conditions that may indicate the underlying genetic diathesis for this condition. Important among these are specific personality disorders; schizotypal, paranoid, and schizoid. Despite specified criteria in the DSM-III-R, demonstration of their validity remains inconclusive and therefore a phenotype for use in genetic analyses is lacking. This article describes the internal structure of these personality disorders. Six hundred and twenty-one relatives of schizophrenic probands in multiple-affected families were examined using a modified SIDP. Latent class analytic techniques were employed to study the interrelationships of the individual DSM-III-R personality disorder criteria. The results reveal a unidimensional structure for DSM-III-R paranoid and schizoid personality disorders. The degree to which an individual belongs to each disorder is related to the number of criteria met. The DSM-III-R criteria defined for schizotypal personality disorder fall into three groups; these are paranoid, schizoid, and “positive symptom” schizotypy. External validation of these classes will be valuable.