Detecting age-related cognitive decline using a visual gist task

Introduction: Individuals age differently. Changes in cognition with increasing age is accepted as a normal part of aging. However, some show more marked but gradual cognitive decline over their lifespan, particularly in memory. This atypical decline in cognitive functioning in the aging population is often referred as mild cognitive impairment. It is thought to be associated with later more serious impairment. Current instruments to detect cognitive decline are insensitive. This study investigated the potential of a visual gist task that measured stimulus recognition and the response latency to recognise stimuli to detect age related changes in cognition. The study used three age groups to examine whether the onset of age-related cognitive decline occurred earlier than the recognised age from previous studies.

Methods: Sixty-six participants aged 20 to 78 years were opportunistically sampled from South-Eastern Queensland to complete computerised tasks assessing visual gist recognition and digit span forward task.

Results: Accuracy of overall Gist memory did not significantly decline with age. However, exploratory correlational analysis indicated a significant increase in semantically related errors with increasing age. Planned comparisons indicated a significant increase in latency for target recognition in older adults than younger adults.

Conclusions: The findings are consistent with the theory of generalised slowing of information processing. Latency of response appears a more sensitive indicator of cognitive decline than accuracy measures. Visual gist task sensitivity may be improved with further instrument refinement to improve the utility of the measure and provide a better diagnostic tool to detect age-related decline.