Intraindividual variability in cognitive performance in older adults: Comparison of adults with mild dementia, adults with arthritis, and healthy adults

Intraindividual variability in latency and accuracy of cognitive performanc e across both trials and occasions was examined in 3 groups of older adults : healthy adults, adults with arthritis, and adults diagnosed with mild dem entia. Participants completed 2 reaction-time and 2, episodic-memory tasks on 4 occasions. Results indicated that intraindividual variability in laten cy was greater in individuals diagnosed with mild dementia than in adults w ho were neurologically intact, regardless of their health status. Individua l differences in variability were stable over time and across cognitive dom ains. Intraindividual variability was also related to level of performance and was uniquely predictive of neurological status, independent of level of performance. Results suggest that intraindividual variability may be a beh avioral indicator of compromised neurological mechanisms.