Sleep macro‐architecture, nocturnal hypoxemia, and Alzheimer's Disease‐related MRI patterns among diverse older adults

Abstract

Background

Increasing evidence has linked sleep quality and sleep apnea to poorer brain health, yet the association between sleep macro‐architecture, nocturnal hypoxemia and Alzheimer's Disease (AD)‐related patterns on neuroimaging remains less known, especially across older adults from diverse ethnoracial groups.

Method

The recently completed Health and Aging Brain Study‐Health Disparities (HABS‐HD)‐Dormir Study recruited community‐dwelling non‐Hispanic White (NHW), Hispanic, and Black participants who underwent an in‐home sleep apnea assessment (WatchPAT, Itamar, IS) and brain magnetic resonance imaging (MRI) to evaluate sleep and AD‐related MRI biomarkers. Sleep stages were estimated using a validated proprietary algorithm. Our primary outcomes are AD‐signature cortical thickness (in individual regions of interests, including entorhinal cortex, fusiform gyrus, inferior temporal gyrus, and middle temporal gyrus, N = 636) and white matter hyperintensities (WMH) volume [log(WMH+1), normalized by intracranial volume, and categorized into tertiles, N = 842]. We applied multivariable linear or ordinal regression models adjusting for age, sex, ethnicity, education, body mass index, cognitive status, smoking, alcohol consumption, and MRI scanner.

Result

A total of 842 elderly participants [34% male; 42% NHW, 33% Hispanic and 25% Black; age 66.18.6 years] were included in the final analysis. Greater light sleep percentage and longer REM sleep latency were independently associated with thinner cortex in AD‐signature regions: standardized β _{light sleep percentage} per 1‐SD increase = ‐0.12 [95% confidence interval (95%CI), ‐0.19 to ‐0.05, false discovery rate (FDR)‐adjusted p = 0.007], β _{REM sleep latency} per 1‐SD increase = ‐0.14 (95%CI, ‐0.21 to ‐0.07, p<0.001); while inverse pattern was observed for deep sleep percentage: β _{deep sleep percentage} per 1‐SD increase = 0.12 (95%CI, 0.05 to 0.19, p = 0.006) (Figure 1). Higher AHI in REM sleep and mean oxygen saturation<94% (the median value of study sample) were independently associated with greater WMH volume: odds ratio_{AHI in REM sleep} per 1‐SD increase = 1.18 (95%CI, 1.02 to 1.36, p = 0.048), odds ratio_{mean oxygen saturation<94%} per 1‐SD increase = 1.38 (95%CI, 1.04 to 1.83, p = 0.049) (Figure 2). There were no ethnoracial interactions for these associations.

Conclusion

Light/deep sleep percentage, longer REM sleep latency, and nocturnal hypoxemia were associated with AD‐related MRI patterns.