The Windows to Functional Decline: Exploration of Eye Movements in Relation to Everyday Task Performance in Younger and Older Adults

Abstract

Research has demonstrated that everyday functional abilities are compromised in mild cognitive impairment (MCI), a transitional stage between normal cognitive aging and dementia, as well as in healthy aging. These functional changes have been shown to be strong predictors of future decline, highlighting their importance. However, early changes in everyday functioning remain poorly characterized, largely due to a scarcity of sensitive measures capable of detecting subtle disruption. Recent research suggests that eye-tracking methodology may be effective in addressing this gap. Fifty-two participants (27 younger adults and 25 non-demented older adults) completed a novel eye-tracking task involving passive viewing of a naturalistic scene and verbalization of a task goal (e.g., make coffee, pack a lunch). Participants also completed a performance-based measure of everyday action that required them to enact the same tasks (e.g., coffee, lunch) that were included in the eye-tracking paradigm, self-report measures of functional ability, and neuropsychological measures. Mixed ANOVAs were conducted to examine group (young, old) and condition (passive viewing, verbalization)/task (simple, complex) effects on eye-tracking and everyday action performance. Independent samples t-tests/Mann-Whitney U tests were conducted to examine group differences in eye-tracking and everyday action performance. Correlation analyses across all measures were conducted to evaluate the potential mechanisms of eye-tracking and everyday action results. Results showed no significant group differences in the primary eye-tracking variables, but both groups made a lower proportion of fixations to distractor (i.e., non-target) objects during task verbalization compared to passive scene viewing. Older adults made more inefficient actions during performance-based everyday task completion, particularly when task demands were high. Eye tracking and everyday action variables were related to different measures of self-reported functional ability. Finally, eye-tracking variables were primarily related to neuropsychological measures of executive functions/working memory, whereas everyday action performance was most strongly related to measures of verbal learning and memory. These findings suggest that age-related functional changes at the level of eye movements may occur after changes in behavioral performance of everyday tasks. Importantly, performance-based assessment of everyday action appears sensitive to age-related decline. Additionally, naturalistic eye movements and everyday task performance may reflect distinct components of self-reported functioning and may be driven by distinct cognitive processes. Future research with refined naturalistic eye-tracking tasks and samples with a wider range of impairment is necessary to further explore these findings and improve characterization and detection of risk for dementia.