Heterogeneity of Cognitive Trajectories in Diverse Older Person

摘要

This study examined trajectories of cognitive change in psychometrically matched measures of episodic memory, semantic memory, and executive function in an ethnically, demographically, and cognitively diverse sample of older persons. Individual rates of change showed considerable heterogeneity in each domain. Baseline clinical diagnosis predicted differential change in semantic memory and executive function (dementia > mild cognitive impairment (MCI) > normal), but average decline in verbal episodic memory was similar across all three diagnostic groups. There was substantial overlap of distributions of cognitive change across baseline diagnostic groups for all three measures. Cognitive change was strongly related to change in clinical diagnosis. Rapid and similar change was present for all three cognitive measures in demented cases and in normals and cases with MCI who progressed clinically. In cognitively normal cases, verbal episodic memory change was greater than change in the other two domains. Global status, measured by the Clinical Dementia Rating scale, predicted change in semantic memory and executive function, while ApoE genotype predicted change in verbal episodic memory, and age had no effect on rates of change in any domain independent of global status and ApoE. Results show important limitations in using cross sectional diagnosis to predict prognosis, and suggest that research to identify robust predictors of cognitive change across the full spectrum from normal to dementia is needed for better early identification of diseases causing progressive decline.