Longitudinal studies of cognition in first episode psychosis: a systematic review of the literature.

Although cognitive deficits are recognized as a core feature in schizophrenia, their evolution over the course of the illness is still debated. Longitudinal studies of cognition in patients after a first episode of psychosis (FEP) provide extremely useful information, in that they include an adequate and realistic baseline measure of cognitive performance, while at the same time minimizing the effect of confounding variables associated with chronicity. The aim of this systematic review was to summarize findings of studies assessing the longitudinal course of neuropsychological deficits in patients with FEP for durations of at least one year. Overall, the neuropsychological deficits that are present following a first episode of psychosis appeared to remain stable over time for periods of up to ten years, the only possible exception being verbal memory deficits, where there is some evidence of further deterioration over the long term. However, further studies are needed to confirm this conclusion, especially in the (somewhat inconsistently defined) domain of executive function. Improvements in psychopathology appear to positively influence the course of cognitive deficits, although the effects of antipsychotic medication are not as clear.