In a recent study published in the journal Scientific Reports, researchers explored how changes in daily step counts and variability affect cognitive function in older adults during a 10-week physical activity intervention.

Study: Association between changes in habitual stepping activity and cognition in older adults. Image Credit: SibRapid / Shutterstock

Background 

Aging often leads to cognitive decline, particularly in executive functions and inhibitory control, which are early indicators of conditions like Alzheimer’s disease. Engaging in regular physical activity can reduce or even reverse these declines in older adults. As the population ages, identifying strategies to preserve cognitive function becomes crucial. While structured exercise in controlled settings has been linked to cognitive health, the effects of habitual, daily physical activity on cognition remain underexplored. Further research is needed to clarify the mechanisms linking physical activity patterns to cognitive improvements and to establish customized intervention strategies for diverse aging populations.

About the study 

In the present study, 43 older adults were recruited, with 37 completing due to incomplete stepping data. Participants were over 55, able to walk independently, cognitively healthy, and free from significant health issues, though some were on medication. They engaged in a 10-week intervention focused on improving cognitive function through group aerobic and resistance activities, aligning with a dynamic socio-ecological model. Participants committed to a minimum of 150 minutes of moderate-to-vigorous activity weekly, with adherence verified by activity logs.

Activity was monitored with Fitbit devices, requiring consistent wear for accurate step count and variability data. Step count validity and variability (using average real variability, ARV) were assessed, focusing on the day-to-day differences in activity levels.

Physical and cognitive assessments pre- and post-intervention included heart rate, blood pressure, body mass index, a six-minute walk test for aerobic fitness, and a computerized Stroop task for cognitive function. The Stroop task evaluated processing speed, inhibitory control, and cognitive flexibility through different stages, with high accuracy and reaction times recorded.

Data analysis, adhering to normality checks and parametric statistics, modeled step counts and variability non-linearly, assessing changes in physical and cognitive measures via paired t-tests and Analysis of Covariance (ANCOVA), and adjusting for demographic factors. Regression analyses explored the relationship between activity changes and cognitive performance, with statistical significance set at p < 0.05.

Study results 

In this study, the majority of participants were female (33 out of 37), and all demonstrated cognitive health with Mini-Mental State Examination (MMSE) scores exceeding 24. Following the intervention, a significant reduction in body mass and body mass index was observed alongside an increase in distance covered during the six-minute walk test (6MWT), indicating physical improvements (all, p < 0.001).

Analysis of stepping data revealed that total step counts increased and day-to-day step variability decreased over the course of the 10-week intervention. These changes were most pronounced at the start and end of the period, with the data fitting best to a cubic model, signifying a non-linear relationship in both total steps taken and in the variability of these steps from day to day. The intervention increased overall physical activity levels, as evidenced by higher step counts while promoting more consistent activity patterns among participants, as shown by reduced variability in day-to-day step counts.

Cognitive outcomes measured through a computerized Stroop task before and after the intervention revealed notable improvements. Specifically, reaction times during the simple naming condition were faster post-intervention, indicating enhanced processing speed. Although the inhibition condition did not significantly improve, the switching condition, which tests cognitive flexibility and is considered the most challenging, exhibited faster completion times post-intervention. 

When examining the relationship between changes in physical activity and cognitive performance, the study found no significant association between the increase in total step counts and improvements in reaction time for any of the Stroop task conditions (naming, inhibition, and switching). However, a significant positive association was observed between reductions in day-to-day step variability and faster reaction times in the switching condition. 

Conclusions 

To summarize, this study confirmed that stabilizing daily step variability, rather than increasing total step count, led to faster reaction times in the Switching task of the Stroop test, indicating improved cognitive flexibility in older adults. This suggests promoting consistent daily physical activity as a potential strategy for enhancing executive function. The Stroop task showed that such cognitive flexibility improvements could significantly lower the risk of cognitive disorders. The findings challenge current physical activity guidelines by suggesting that daily consistency, alongside a high number of steps, may better support cognitive health in older adults. This personalized physical activity intervention increased average step counts, reduced variability, and enhanced cognitive flexibility, indicating its potential as a model for encouraging consistent daily activity among older adults.