Neurocognitive performance in first-episode and chronic schizophrenic patients.

Previous research on neuropsychological disturbances in first-episode and chronic schizophrenic patients has provided mixed results which can be partially attributed to methodological inconsistencies. For the present study, 70 schizophrenic patients (40 with chronic and 30 with first-episode schizophrenia) were compared to 30 healthy controls on a large battery of neuropsychological tests. Special attention was paid to potential confounds such as differences in psychopathology, age and educational level between the schizophrenic sub-samples. Healthy controls performed better than both first-episode and chronic patients in almost all cognitive domains (P < 0.01), while the patient samples did not differ in any of the tasks. Results were confirmed in a second series of analyses in which patient subgroups were equated for sociodemographic background variables. The present results confirm recent data collected in longitudinal studies, thus, lending further support for a neurodevelopmental model of schizophrenia. It is suggested that neuropsychological disturbances occur early in schizophrenia and do not worsen in the course beyond age-related decrement. Possible reasons why previous research has produced contradictory findings are discussed.