British Journal of Psychiatry (1992), 161, 69—74 Estimation of Premorbid Intelligence in Schizophrenia

in the community. Schizophrenic patients were individually matched for age, sex, and education with a healthy, normal subject. Both schizophrenic samples scored significantly lower on the Wechsler Adult Intelligence Scale (WAIS) than their respective control groups. NART-estimated IQ did not differ significantly between the community-resident schizophrenics and their controls, suggestingthat the NARTprovidesa validmeansof estimatingpremorbidintelligenceinsuch a population. NART-estimated lQ was significantly lower in the long-stay sample than in their controls. Although low NART scores in this latter sample could be a valid reflection of low premorbid lQ, the alternative explanation that NART performance was impaired by onset of the diseasecannot be ruledout. A valid means of estimating premorbid intelligence in schizophrenia would be of benefit to both clinicians and researchers. It is clear from a host of studies (see Aylward et al, 1984) that schizophrenia can be associated with intellectual impairment. However, because of the wide variationin intellectua