108. Neurocognitive predictors of functional decline in poor-outcome schizophrenia

Abstract

Although cognitive abilities have been shown to be directly related to social, occupational, and adaptive functioning in patients with schizophrenia, there is no evidence indicating that a specific neuropsychological index can predict decline in functional status. Impairments in verbal learning and memory, verbal skills, and executive functions correlate with functional impairments, and are predictive of functional ability over time. Yet, there is no evidence that impairment on a specific neurocognitive index is associated with functional decline, or whether these measures are all associated with functional impairments due to a global or specific cognitive deficit. In order to test whether any of these neuropsychological measures (Verbal Learning and Memory, Praxis, and Confrontational Naming) is most associated with functional decline, 68 subjects were chosen from a long-term study of the effects of aging in schizophrenia. Subjects were chosen specifically because they declined functionally from a mildly impaired level of functioning to a moderate or severely impaired level of functioning across two assessments (mean interval 5 1.89 years, sd 5 1.42 years), based on a global rating of functioning on the Clinical Dementia Rating Scale (CDR). Age and education corrected z-scores were derived for measures of verbal learning, delayed memory, praxic ability, and confrontational naming, based on performance of healthy controls on these measures as part of the Consortium to Establish a Registry of Alzheimer’s Disease (CERAD). Change in performance on these neuropsychological measures was calculated by subtracting the standardized z-score of each measure at the follow-up assessment from the standardized score obtained on each measure at the initial assessment. A repeated measures ANOVA was used to determine if any of these measures were specifically associated with functional decline. Whereas the overall ANOVA was significant (F(1, 67) 5 14.49, p , .001), no specific measure of neurocognitive functioning was able to account for the decline in functional ability (Rao’s R (3, 65) 5 1.19, p , .321). These data suggest that the cognitive decline seen in these patients is generalized, rather than selective. It may be that this functional decline is related to low levels of cortical decline in patients with poor premorbid functioning and a chronic clinical course of illness.