Association Between Sleep Duration and Cognitive Decline

Yanjun Ma,Le Shi,Baoliang Zhong,Wuxiang Xie,Lirong Liang,Fanfan Zheng

doi:10.1001/jamanetworkopen.2020.13573

Abstract

An association between sleep duration and the trajectory of cognitive decline has not been conclusively demonstrated. To investigate the association between sleep duration and cognitive decline by a pooled analysis of 2 nationally representative aging cohorts. A pooled cohort study using data from waves 4 to 8 (2008-2009 to 2016-2017) in the English Longitudinal Study of Ageing and waves 1 to 3 (2011 to 2015) in the China Health and Retirement Longitudinal Study in a population-based setting. Participants were 2 randomly enrolled cohorts comprising 28 756 individuals living in England who were 50 years or older and those living in China who were 45 years or older. Self-reported sleep duration per night according to face-to-face interviews. Global cognitive z scores were calculated according to immediate and delayed recall test, an animal fluency test, the serial sevens test, an intersecting pentagon copying test, and a date orientation test. Data were analyzed from 20 065 participants, including 9254 from the English Longitudinal Study of Ageing (mean [SD] age, 64.6 [9.8] years; 55.9% [5174 of 9254] women; median follow-up duration, 8 [interquartile range, 6-8] years) and 10 811 from the China Health and Retirement Longitudinal Study (mean [SD] age, 57.8 [9.0] years; 50.2% [5425 of 10 811] men; median follow-up duration, 4 [interquartile range, 4-4] years). During 100 000 person-years of follow-up, global cognitive z scores in individuals with 4 hours or less (pooled β = -0.022; 95% CI, -0.035 to -0.009 SD per year; P = .001) and 10 hours or more (pooled β = -0.033; 95% CI, -0.054 to -0.011 SD per year; P = .003) of sleep per night declined faster than in the reference group (7 hours per night) after adjusting for a number of covariates. An inverted U-shaped association between sleep duration and global cognitive decline was also observed. In this pooled cohort study, an inverted U-shaped association between sleep duration and global cognitive decline was found, indicating that cognitive function should be monitored in individuals with insufficient (≤4 hours per night) or excessive (≥10 hours per night) sleep duration. Future studies are needed to examine the mechanisms of the association between sleep duration and cognitive decline.

Highlights

The proportion of older people has increased rapidly in recent decades such that 12% of the global population in 2015 was 60 years or older.[1]
Data were analyzed from 20 065 participants, including 9254 from the English Longitudinal Study of Ageing and 10 811 from the China Health and Retirement Longitudinal Study
An inverted U-shaped association between sleep duration and global cognitive decline was observed. In this pooled cohort study, an inverted U-shaped association between sleep duration and global cognitive decline was found, indicating that cognitive function should be monitored in individuals with insufficient (Յ4 hours per night) or excessive (Ն10 hours per night) sleep duration

Summary

Introduction

The proportion of older people has increased rapidly in recent decades such that 12% of the global population in 2015 was 60 years or older.[1] By 2050, this proportion is projected to be greater than one-fifth of the population.[1] the number of older adults with cognitive impairment and dementia is increasing rapidly.[2] Dementia is one of the most common and serious disorders in later life It is responsible for a large proportion of disability and mortality in older people and imposes a huge burden of long-term care for families and society.[3] No effective therapies are available for treating dementia; the development of dementia prevention strategies has become a priority.[4,5] During the long preclinical phase of dementia, accelerated cognitive decline is regarded as a cardinal marker. The identification of risk factors for cognitive decline is of great significance for dementia prevention

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Discussion

Conclusion