Excess brain age in the sleep electroencephalogram predicts reduced life expectancy

Abstract

The brain age index (BAI) measures the difference between an individual's apparent "brain age" (BA; estimated by comparing EEG features during sleep from an individual with age norms), and their chronological age (CA); that is BAI = BA-CA. Here, we evaluate whether BAI predicts life expectancy. Brain age was quantified using a previously published machine learning algorithm for a cohort of participants ≥40 years old who underwent an overnight sleep electroencephalogram (EEG) as part of the Sleep Heart Health Study (n = 4877). Excess brain age (BAI >0) was associated with reduced life expectancy (adjusted hazard ratio: 1.12, [1.03, 1.21], p = 0.002). Life expectancy decreased by -0.81 [-1.44, -0.24] years per standard-deviation increase in BAI. Our findings show that BAI, a sleep EEG-based biomarker of the deviation of sleep microstructure from patterns normal for age, is an independent predictor of life expectancy.

Keywords: Biomarker; Brain age; EEG; Life expectancy; Mortality; Sleep.

Conflict of interest statement

Disclosure statement

The authors declare no conflict of interest.

Copyright © 2019 Elsevier Inc. All rights reserved.

Figures

Fig. 1.

(A). Survival curves (multivariate Weibull regression models) for a participant with BAI = +36.8 versus BAI = −36.8 years (+/− 3 standard deviations of BAI). The area under each survival curve is the life expectancy. The difference in area under the 2 curves is 5.1 years. (B). The change in life expectancy as a function of BAI, relative to a baseline BAI = 0. For an increase in BAI of one standard deviation (12.3 years), life expectancy decreases by 0.85 years. Similarly, for participants with younger-appearing sleeping brain activity (negative BAI), life expectancy is increased. Abbreviations: BAI, brain age index.