Article Neuropsychological Decline in Schizophrenia From the Premorbid to the Postonset Period: Evidence From a Population-Representative Longitudinal Study

Objective: Despite the widespread belief that neuropsychological decline is a cardi-nal feature of the progression from the premorbid stage to the chronic form of schizophrenia, few longitudinal studies have examined change in neuropsycho-logical functioning from before to after illness onset. The authors examinedwhether neuropsychological decline is unique to schizophrenia, whether it is generalized or confined to particularmental functions, and whether individuals with schizophrenia also have cognitive problems in everyday life. Method: Participants were members of a representative cohort of 1,037 individu-als born in Dunedin, New Zealand, in 1972 and 1973 and followed prospectively to age 38, with 95 % retention. Assessment of IQ and specific neuropsychological func-tions was conducted at ages 7, 9, 11, and 13, and again at age 38. Informants also reported on any cognitive problems at ag