Variability in Health Behaviors Over 14 Years Predicts Later Cognitive Outcomes

TL;DR

Stable health behaviors like exercise and sleep over 14 years are linked to better cognitive outcomes later in life.

Contribution

This study shows that variability in exercise and sleep over time predicts later cognitive decline.

Findings

Higher variability in exercise scores over 14 years was linked to lower cognitive scores later.

Greater variability in sleep hours also correlated with worse cognitive outcomes.

Stable health behaviors are important for maintaining cognitive function in aging.

Abstract

Engaging in healthy behaviors is important for maintaining cognitive functioning throughout the lifespan. We assessed whether variability in physical exercise and hours of sleep over a fourteen year period are associated with subsequent cognitive performance among Health and Retirement Study (HRS) participants aged 50-69 in 2004. We calculated variability in exercise and sleep across 7 biennial assessments by dividing the standard deviation of each participant’s biennial scores by the mean of the participant’s exercise or sleep score over the 14 year interval. Linear Regression analyses of participants aged 50-59 (n = 2370) at baseline revealed that higher initial cognition and educational levels, and female gender were associated with higher cognitive scores 14 years later. Although baseline levels of exercise and mobility were not associated with cognitive scores 14 years later, older age, more chronic conditions at baseline, and higher variability in exercise scores over the 14 years were negatively associated with cognitive scores in 2018. Similar results were found for participants aged 60-69 (n = 2738). We replicated the analyses described above to assess the association between variability in hours of sleep and subsequent cognitive functioning and found very similar findings. Importantly, we also found that the greater variability in biennial assessments of sleep was negatively associated with cognitive functioning 14 years later for those aged 50-59 (n = 743) at baseline, and 60-69 (n = 889) at baseline. The findings reveal the importance of considering variability in health behaviors when assessing their impact on future cognitive functioning and the importance of maintaining health behaviors throughout adulthood.