Associations of Alzheimer’s disease Plasma Biomarkers' and slow wave sleep within Black and White Cognitively Normal Older‐Adults

Abstract

AbstractBackgroundWe studied whether plasma levels of Aβ40, Aβ42, Aβ42/Aβ40, Tau, tau/Aβ42 and NfL are associated with slow wave sleep, and if this association varied within non‐Hispanic Whites and Blacks/African‐Americans.MethodThis was a cross‐sectional analysis of baseline data from 171 cognitively normal older‐adults, volunteering in active NYU studies on memory and sleep. Plasma Aβ40, Aβ42, Tau and NfL were measured using single molecule array (SIMOA). Non‐rapid eye movement sleep (NREM) slow wave sleep (SWS) duration was assessed from 2 nights of in‐lab NPSGs. Associations of NREM SWS duration and plasma AD biomarker levels were examined by applying adjusted generalized linear models and Pearson correlation analysis after data normalization. Analyses were adjusted for age, sex, BMI, race, and education.ResultOf the 171 subjects (128 Whites and 43 Blacks), 112 (65.5%) were females, and mean (SD) age was 68.6 (6.6) years, BMI was 27.6 (6.1) kg/m**2, and education was 16.9 (2.1). There were no racial differences in age, sex, and BMI, SWS and AHI4%. In comparison to whites, blacks had significantly lower years of education (14.2 vs. 17.2, p <.01). Black/African‐American subjects had significantly lower plasma Aβ40 (248.3 vs. 262.5 pg/ml) and NfL levels (11.4 vs. 15.2 pg/ml). p<.05 for both. There were no significant racial differences in levels of plasma Aβ42, Aβ42/Aβ40, Tau, Tau/Aβ40 and Tau/Aβ42. NREM SWS duration was not associated with plasma Aβ42, Aβ40 or tau in the overall sample. However, in Whites, SWS negatively correlated with plasma Aβ42 (r = ‐0.28, p< = 0.05). In Black/African‐Americans, SWS positively correlated with plasma Aβ42 (r = 0.48, p = 0.05). In Whites, SWS negatively correlated with plasma Aβ40 (r = ‐0.087, p = 0.72), though not significant. In Black/African‐Americans, SWS positively correlated with plasma Aβ40 levels (r = 0.32, p = 0.04). In Whites, SWS negatively correlated with plasma Tau (r = ‐0.153, p = 0.27), though not significant. In Black/African‐Americans, SWS positively correlated with plasma Tau levels (r = 0.52, p = 0.04). NREM SWS was not associated with plasma tau/Aβ42, plasma tau/Aβ40 or plasma NfL in the overall sample and across racial‐subgroups.ConclusionRace‐specific relationships between NREM SWS and plasma Aβ42, Aβ40 & Tau might propose differences in SDOH mechanisms that may affect sleep and AD‐risk in older‐adults.