Comparison of indices of premorbid function in schizophrenia

There has been a resurgence of interest in the area of premorbid functioning in schizophrenia as it provides clues to onset and etiology. Most studies rely on retrospective estimates of premorbid status that are incomplete, such as the Premorbid Adjustment Scale (PAS). Even prospective high-risk studies are hampered by the narrow range of premorbid functions assessed and are thus unable to answer crucial questions related to onset of illness. This study was undertaken to assess the relationship between several indices of premorbid functioning. Sixty four in-patients with schizophrenia were assessed at medication-free baseline and post-treatment with BPRS and SANS. PAS scores were derived from all available sources. Premorbid cognitive ability was estimated by the mean of WAIS-R Vocabulary and Information subscale scores. Estimated premorbid IQ was obtained using a demographic regression formula. Years of education and predicted VIQ, PIQ, and FSIQ were found to correlate with estimated premorbid cognitive ability. Predicted VIQ, PIQ, and FSIQ were associated with years of education and PAS childhood, early and late adolescence, and general scores. Each estimate of premorbid ability demonstrated a different pattern of association with clinical ratings, symptom change, and outcome. The results suggest that education, PAS, predicted IQ, and WAIS-R estimates of premorbid cognitive ability assess different but overlapping areas of pre-morbid functioning.