Insomnia Mediates the Effects of Psychological Stress on Cognitive Decline Among Older Adults over 10 years: Insights from Health and Retirement Study

Previous studies suggest associations between chronic stress, poor sleep, and cognitive function in older adults; however, few studies have formally examined this association longitudinally. Given the prevalence of age-related sleep disturbances and the widespread use of pharmacotherapies with deleterious effects on cognition and other health outcomes (e.g., benzodiazepine receptor agonists), this question is of high public health importance.The University of Michigan’s Health and Retirement Study (HRS) involves approximately 20,000 older American adults, sampled biannually via paper or electronic surveys, telephone interviews, and other examinations (Health and Retirement Study [HRS], 2024). The publicly available study database spans 1992-2024 and includes data on participant cognition, health behaviors, sociodemographic characteristics, and other clinical information. The present analysis utilized data from 2010 to 2020. Notably, 2012 was excluded due to sleep-related items not being asked in that year.
Self-reported chronic stress (8-item scale) and insomnia scores (4-item scale) were operationalized as the independent (i.e., predictor) variables of cognitive status. Zero-order correlations, regression, and mediation analyses were initially performed cross-sectionally with 2010 and 2014 participant data, as a complete case analysis. Subsequently, longitudinal analyses were performed by implementing Generalized Estimating Equations and a Fine-Gray Cox Proportional Hazards Model using 2010 or 2014 baseline participants with normal cognition.
The objective of this study is to explore cross-sectional and longitudinal associations between chronic psychological stress, sleep, and cognitive function in older adults. More specifically, we hypothesize that insomnia mediates the association between chronic stress and incident cognitive decline in older adults averaged 60 years and older. This led to population predictions that those, who on average, report more stress and more insomnia will have a higher probability of incident cognitive decline over time.