The role of sleep disturbance in cognitive outcomes among lonely adults in the health and retirement study

Abstract Both sleep disturbance and loneliness have been linked to poorer cognitive performance and increased risk of dementia in older adults. Loneliness is believed to influence cognitive functioning directly and indirectly through the HPA axis dysfunction, which increases systemic inflammation through endocrine, immune system, and genetic pathways which produce a range of negative effects on brain tissue. Higher levels of HPA axis activity associated with lonely feelings may lead to poorer sleep quality, which decreases beta-amyloid and tau clearance, as well as memory consolidation, which may further disrupt sleep through alterations in brain tissue. Despite the growing body of research, little is known about how sleep disturbance and loneliness, both modifiable risk factors, interact to effect cognition and dementia risk over time. Secondary analysis of the 2006, 2010, 2014, and 2018 waves of the Health and Retirement Study was completed using data from 1,092 participants (mean age: 66.24; SE: .1366). Mixed effects regression modeling was used to evaluate the role of sleep disturbance in the relation between loneliness (R-UCLA loneliness scale, 11 item) and four cognitive performance measures: Immediate and Delayed Word Recall, Serial 7s, and Backward Count, and cognitive status category (cognitively normal, cognitively impaired, and dementia) across a 12-year period. Sleep disturbance moderated the relation between loneliness and Immediate Word Recall (p=.048) and Serial 7s (p=.032) outcomes even after controlling for demographic covariates and depression. Findings suggest that sleep disturbance may exacerbate the negative physiological effects of loneliness on episodic memory and executive functioning in older adults.