Correlation between moderate daily physical activity and neurocognitive variability in healthy elderly people.

Recent studies have reported that moderate physical activity in daily life contributes to maintenance of a proper state of cognitive function in elderly individuals. The present study investigated the validity of correlations between moderate physical activity and cognitive function using more objective and detailed assessments of both physical activity and neurocognitive function. Participants comprised 72 healthy elderly individuals who wore an electronic accelerometer during waking hours for 3 months. This device recorded the number of steps per day as well as the duration of each intensity level in daily life; levels 1-3 were the equivalent of easy-paced walking (light activity), while levels 4-6 corresponded to brisk walking (moderate activity). To estimate executive cognitive ability in healthy elderly individuals, performance variability of executive control was examined with a task-switching reaction time (RT) test measuring intra-individual variability (IIV) in RTs. In 43 consenting participants, functional magnetic resonance imaging (fMRI) during the task-switching RT trial was analyzed to assess differences in brain activity patterns as a function of daily physical activity. Daily duration of level 4 physical activity correlated negatively with and significantly predicted IIV. Moreover, fMRI analysis confirmed that the higher physical activity group (duration of level 4 activity ≥ 26.4 min/day) showed significantly reduced age-related functional attenuation of prefrontal activations during the task-switching RT trial. The study discusses the possibility that enhancing the moderate daily physical activity could be helpful for lowering the rate of neurocognitive degradations in healthy elderly individuals.