Patterns of sleep disturbances across stages of cognitive decline

Abstract

Objectives:The purpose of this study was to investigate insomnia symptoms and excessive sleep/sluggishness across stages of cognitive decline (cognitively normal [CN], Cognitively Impairment, Not Demented [CIND], dementia) in a large, racially/ethnically diverse sample of older adults (70+) in the US. We also examined whether sleep disturbances at baseline predicted conversion to CIND or dementia at follow-up. Methods: In this secondary analysis of the Aging, Demographics, and Memory Study (ADAMS) supplement of the Health Retirement Study, we analyzed patterns of informant-reported insomnia and excessive sleep symptoms among three groups of older adults (n = 846): CN, CIND, and dementia.Results: CIND adults were significantly more likely to have informant-reported insomnia symptoms than those in the CN group (p = 0.013). This was driven by a significant race/ethnicity-by-insomnia interaction with diagnostic status (p = 0.029), such that CIND Black and Hispanic older adults had increased insomnia symptom rates compared to CN, whereas White adults had similar insomnia symptoms across diagnostic status. Across all racial/ethnic groups, the prevalence of excessive sleep symptoms increased stepwise from CN to CIND to dementia (p < 0.001). Overall, insomnia symptoms at baseline predicted conversion from CN to CIND (p < 0.001, OR = 0.288; 95% CI: 0.143-0.580) at 4-year (approximate) follow-up; there was no relationship between baseline insomnia or excessive sleep/sluggishness symptoms and conversion from CIND to dementia. Discussion/Conclusion:This study provides evidence for the increased risk of insomnia symptoms among Hispanic and Black older adults with CIND, and indicates that insomnia symptoms may be associated with increased risk for development of cognitive impairment.

Interrelationship of Sleep Disturbances and Cognitive Status on Mortality

“…Sleep disturbances differentially impacted survival time depending on cognitive status, wherein there was a greater negative impact among participants with MoCA scores between 24-27, a range that captures normal cognition and the cusp of mild cognitive impairment. Previous research has found that the presence of insomnia symptoms at baseline (similar to our study’s “visit #1”) predicted conversion from cognitively normal to cognitively impaired, not demented (CIND, 33 and MCIover time, but not from MCI to dementia. While these previous studies did not examine the impact of sleep disturbances on mortality, there are interesting parallels with worse outcomes associated with higher cognitive status (normal cognition or MCI).…”

Factors associated with reduced sleep among spouses and caregivers of older adults with varying levels of cognitive decline

“…As detailed in our recent paper examining patterns of sleep disturbances across stages of cognitive decline, 30 ADAMS participants were a subset of the 1770 HRS respondents aged ≥70 from the 2000 and 2002 waves of HRS data collection. Sampling strategy for ADAMS participants included ensuring there were sufficient participants from each cognitive stratum, ranging from ‘low functioning’ to ‘high normal’ (which was determined by a self‐ or proxy‐cognitive assessment measure in the parent HRS study), and oversampling Hispanic and Black participants to achieve a nationally representative racial/ethnic sample of older adults 31 .…”