Age-associated differences in cognitive performance in older community dwelling schizophrenia patients: differential sensitivity of clinical neuropsychological and experimental information processing tests.

Cognitive dysfunction is a common feature of schizophrenia and deficits are present before the onset of psychosis, and are moderate to severe by the time of the first episode. Controversy exists over the course of cognitive dysfunction after the first episode. This study examined age-associated differences in performance on clinical neuropsychological (NP) and information processing tasks in a sample of geriatric community living schizophrenia patients (n=172). Compared to healthy control subjects (n=70), people with schizophrenia did not differ on NP tests across age groups but showed evidence for age-associated cognitive worsening on the more complex components of an information-processing test. Age-related changes in cognitive function in schizophrenia may be a function of both the course of illness and the processing demands of the cognitive measure of interest. Tests with fixed difficulty, such as clinical NP tests, may differ in their sensitivity from tests for which parametric difficulty manipulations can be performed.