Course of cognitive symptoms in schizophrenia: a review of the literature.

Longitudinal studies are the only ones capable of responding to the question of whether cognitive deficits present in schizophrenia follow a stable course and establishing its evolutive relationship with other clinical symptoms of the disease. This article reviews a total of 30 studies published in patients with a first psychotic episode or chronic or geriatric patients, with a minimum follow-up period of 1 year. The diversity in criteria and methods used significantly limits the conclusions that can be drawn on this subject. However, the global tendency of the results suggests that significant and measurable cognitive symptoms are present at the onset of the disease and these remain stable in the subsequent period between 2 and 5 years. Their deterioration increases with the course of the disease, especially in hospitalized patients, it not exceeding the deterioration level presented in other degenerative diseases. The authors are aware that unifying research criteria and overcoming the methodological limitations may offer results that change the conclusions herein gathered in the future.