Predicting Alzheimer disease using premorbid neuropsychological performance

Abstract

Individuals with Alzheimer Disease (AD) exhibit deficits across multiple cognitive domains years before clinical diagnosis, when they are in the preclinical stages of the disease. Four studies were conducted to (a) examine the preclinical neuropsychological characteristics of English- and French-speaking Alzheimer Disease (AD) participants from the Canadian Study of Health and Aging (CSHA) and (b) determine the utility of select CSHA neuropsychological and demographic measures in predicting AD over a five-year period. Both English- and French-speaking AD participants demonstrated cognitive changes on episodic memory, verbal fluency, and speeded visuomotor processing tasks five years prior to diagnosis, however declines in performance between initial- and re-assessment were not uniform across these domains for either language group. Advanced age and declines in delayed episodic memory were the most significant indicators of progression to AD over a five-year period for both language groups. A validation study was conducted to investigate how well the predictors of AD prognosticate diagnostic outcome for an independent group of at-risk English-speaking participants. The best predictors of AD for the English-speaking group (age, episodic memory, and speeded visuomotor processing) accurately classified close to 70% of individuals from the at-risk sample. The present findings will contribute to diagnostic decisions regarding AD in older English- and French-speaking Canadian adults.