IQ scores of treatment-resistant schizophrenia patients before and after the onset of the illness.

In this study we examined the correlations of actual pre-morbid IQ scores (obtained from routine educational assessments) and estimated current IQ scores in 27 treatment-resistant schizophrenia patients. Pre-morbid (mean = 93) and current (mean = 83) IQ scores were significantly correlated (r = 0.807, P < 0.0001), while duration of illness (10-40 years) was unrelated to the magnitude of IQ score decline (r = -0.103, P = 0.575). These data suggest that pre-morbid IQ test scores are highly predictive of post-morbid scores.