THE ROSCOMMON FAMILY STUDY .2. THE RISK OF NONSCHIZOPHRENIC NONAFFECTIVE PSYCHOSES IN RELATIVES

Objective: We sought to clarify the familial relationship between the nonschizophrenic, nonaffective psychoses (schizoaffective disorder [SA D], schizophreniform disorder, delusional disorder, and atypical psych osis) and schizophrenia and affective illness (AI). Designs: A case-co ntrolled epidemiologic family study using DSM-III-R criteria. Results: Compared with relatives of unscreened controls, the risk of nonschizo phrenic, nonaffective psychoses was significantly elevated in relative s of probands with schizophrenia, SAD, schizotypal personality disorde r, and psychotic AI. No significant elevation in risk to these disorde rs was seen in relatives of probands with nonpsychotic AI. The risk fo r SAD alone was significantly increased in relatives of probands with psychotic or bipolar AI. Conclusions: The nonschizophrenic, nonaffecti ve psychoses have a significant familial relationship with both schizo phrenia and schizotypical personality disorder. Schizoaffective disord er, as defined by DSM-III-R, shares familial etiologic factors with at least some forms of AI.