Sleep and APOE‐ε4 have a synergistic effect on plasma biomarkers and longitudinal cognitive decline in older adults

Abstract

AbstractBackgroundSleep disorders are prevalent among patients with Alzheimer's disease (AD), and the APOE ε4 genotype is a key genetic risk factor for sporadic AD. However, the combined effect of the genotype and sleep disorders on cognitive decline remains uncertain.MethodsA total of 972 participants were drawn from the SILCODE cohort, comprising 655 without the ε4 allele (APOE−) and 317 with ε4 allele (APOE+). Data were collected, including neuropsychological assessments, sleep measurements, plasma biomarkers, and PET imaging. A Sleep Composite Index (SCI) was created, categorizing participants into high risk (Sleep+) and low risk (Sleep−).ResultsSignificant predictions of dementia risk associated with plasma p‐tau181, neurofilament light chain (NfL), and SCI. Individuals with both Sleep+ and APOE+ had a higher risk of dementia compared to those with Sleep‐. The Sleep+/APOE+ group had higher plasma NfL levels than the Sleep−/APOE− group. Similar trends emerged in plasma NfL levels among the Aβ PET‐positive subgroup. Plasma NfL levels explained 23% of the relationship between SCI and cognitive impairment.ConclusionOur study highlights sleep disorder was associated with cognitive decline, with plasma NfL playing a partial mediating role. These findings explain how sleep disorders affect cognitive function and emphasize the importance of healthy sleep for older adults.