Associations of sleep disturbances with cognitive function and plasma Alzheimer’s biomarkers in Chinese rural‐dwelling older adults: A population‐based study

Abstract

AbstractBackgroundSleep disturbances have been associated with cognitive impairment, but their associations with plasma Alzheimer’s disease (AD) biomarkers have been rarely explored. We sought to investigate the relationships of self‐reported and cardiopulmonary coupling (CPC)‐assessed sleep disturbances, cognitive function, and plasma AD biomarkers among rural‐dwelling older adults in China.MethodThis population‐based cross‐sectional study included 1987 dementia‐free individuals (age ≥60 years, 55.0% women) who participated in the CPC‐substudy as part of the baseline assessments of the MIND‐China Study; of these, 830 had data on plasma Aβ42, Aβ40, total‐tau, and neurofilament light chain (NfL) that were measured using the single molecule array (SIMOA) technology. We collected data via face‐to‐face interviews, clinical examinations, and neuropsychological test. Sleep disturbances were assessed using the Pittsburgh Sleep Quality Index (PSQI), the Epworth Sleepiness Scale (ESS), the self‐administered Berlin Questionnaire, and the ECG‐based CPC analysis. We used the neuropsychological test battery to assess memory, language, attention, and executive function. Data were analyzed using logistic and general linear regression models.ResultOf the 1987 participants, CPC‐measured total sleep time (TST) >8 hours/night (vs. 5‐8 hours) was significantly associated with a lower composite z‐score of memory (β = ‐0.080; 95% CI = ‐0.160 ‐ ‐0.001), language (‐0.114; ‐0.186 ‐ ‐0.042), attention (‐0.104; ‐0.175 ‐ ‐0.033), and executive function (‐0.117; ‐0.193 ‐ ‐0.041). Self‐reported poor sleep quality was associated with a lower composite z‐score of attention function (β = ‐0.077; 95% CI = ‐0.143 ‐ ‐0.011). Self‐reported excessive daytime sleepiness (EDS) was associated with a lower composite z‐score of memory (β = ‐0.217; 95% CI = ‐0.350 ‐ ‐0.084), language (‐0.182; ‐0.303 ‐ ‐0.061), and attention function (‐0.162; ‐0.282 ‐ ‐0.041). In the plasma biomarker subsample, CPC‐measured TST >8 hours/night was significantly associated with lower plasma Aβ42/Aβ40 ratio (β = ‐0.522; 95% CI = ‐0.764‐ ‐0.281) and higher plasma concentrations of Aβ40 (13.419; 6.515‐20.323), total‐tau (0.216; 0.071‐0.360), and NfL (0.071; 0.002‐0.140). There was no significant association between CPC‐measured apnea hypopnea index (AHI) and plasma AD biomarkers (P>0.05).ConclusionLong sleep duration and self‐reported EDS were associated with poor memory, language, and attention function among older adults, in which AD pathology and neurodegeneration may be the common pathways linking sleep disturbances with cognitive impairment.