Sleep Time Estimated by an Actigraphy Watch Correlates With CSF Tau in Cognitively Unimpaired Elders: The Modulatory Role of APOE.

Sara López-García,Ana Pozueta,Martha Kazimierczak,Juan Irure,Carmen Lage,Eloy Rodríguez-Rodríguez,Luis Reyes-González,Andrea Fernández-Rodríguez,María García-Martínez,Marcos López-Hoyos,María Bravo,Pascual Sánchez-Juan

doi:10.3389/fnagi.2021.663446

Abstract

There is increasing evidence of the relationship between sleep and neurodegeneration, but this knowledge is not incorporated into clinical practice yet. We aimed to test whether a basic sleep parameter, as total sleep estimated by actigraphy for 1 week, was a valid predictor of CSF Alzheimer’s Disease core biomarkers (amyloid-β-42 and –40, phosphorylated-tau-181, and total-tau) in elderly individuals, considering possible confounders and effect modifiers, particularly the APOE ε4 allele. One hundred and twenty-seven cognitively unimpaired volunteers enrolled in the Valdecilla Study for Memory and Brain Aging participated in this study. Seventy percent of the participants were women with a mean age of 65.5 years. After adjustment for covariates, reduced sleep time significantly predicted higher t-tau and p-tau. This association was mainly due to the APOE ε4 carriers. Our findings suggest that total sleep time, estimated by an actigraphy watch, is an early biomarker of tau pathology and that APOE modulates this relationship. The main limitation of this study is the limited validation of the actigraphy technology used. Sleep monitoring with wearables may be a useful and inexpensive screening test to detect early neurodegenerative changes.

Highlights

Sleep disturbances are very common in Alzheimer’s disease (AD) and represent a major clinical problem (Pollak and Perlick, 1991; Moran et al, 2005)
Sex, and APOE ε4 status, we found that total sleep was associated with t-tau (β = −0.96; p = 0.00036) and p-tau (β = −0.14; p = 0.0072)
We found an inverse correlation between total sleep time and CSF levels of t-tau (r = −0.32; p = 0.001) and p-tau (r = −0.26; p = 0.005); no significant association was found with Aβ42/40 (Figure 1)

Summary

Introduction

Sleep disturbances are very common in Alzheimer’s disease (AD) and represent a major clinical problem (Pollak and Perlick, 1991; Moran et al, 2005). Studies have explored the relationship between tau and sleep (Kam et al, 2019; Lucey et al, 2019) The majority of these studies have used self-reported questionnaires to evaluate sleep (Spira et al, 2014; Sprecher et al, 2015; Branger et al, 2016; Brown et al, 2016). Sleep was assessed by one-night in-lab polysomnography (PSG) (Varga et al, 2016)

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