Course of schizophrenia: neuropsychological evidence for a static encephalopathy.

The course of cognitive function in schizophrenia has often been debated. In one view, it is thought to be akin to that of a progressive dementia with relentless cognitive decline. In another view, the deficits are thought to remain relatively stable, analogous to those of a static encephalopathy. Review of longitudinal and cross-sectional studies strongly supports the latter interpretation. In particular, we present data from a recent cross-sectional study in which cohorts of patients in their third, fourth, fifth, sixth, and seventh decades of life were administered a battery of tests known to be sensitive to progressive dementing diseases. All patients were carefully screened to exclude those with neurologic, systemic, or psychiatric comorbid conditions, and cohorts were matched on estimated premorbid intellectual capacity. Although scores on most tests were impaired, no evidence of decline across groups was observed. These results are also consistent with neuroimaging and neuropathological studies in that no evidence for an active degenerative process has been discovered.