Alzheimer's Imaging Consortium

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.

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.

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.

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