Premorbid IQ in patients with functional psychosis and their first-degree relatives

Numerous studies have found deficits in premorbid IQ in schizophrenic patie nts, but it is not clear whether this deficit is shared by (a) patients wit h other functional psychoses, and (b) relatives of these patients. Ninety-o ne schizophrenic patients, 66 affective psychotic patients (29 schizoaffect ive and 37 manic or depressed), and 50 normal control subjects were adminis tered the National Adult Reading Test (NART) which provides an estimate of premorbid IQ. The NART was also completed by 85 first-degree relatives of s chizophrenic patients and by 65 first-degree relatives of affective psychot ic patients. After adjustments were made for sex, social class, ethnicity a nd years of education, schizophrenic patients had significantly lower premo rbid IQ than their relatives, the affective psychotic patients and controls . Manic and depressed patients had significantly lower NART scores than the ir first-degree relatives, but schizoaffective patients did not, and neithe r group differed significantly from controls. There was no significant diff erence in premorbid IQ between patients who had experienced obstetric compl ications (OC +) and those who had not (OC -). Both OC + and OC - schizophre nic patients differed significantly from their relatives, but the disparity was greatest between OC + patients and their relatives. Relatives of OC schizophrenic patients had significantly higher IQ than relatives of OC - s chizophrenic patients. (C) 2000 Elsevier Science B.V. All rights reserved.