Longitudinal associations between sleep duration and cognitive impairment in Chinese elderly

Abstract

BackgroundAge-associated cognitive decline has become a major threat to both personal welfare and public health and can further develop into Dementia/Alzheimer’s disease. Sleep is significantly correlated with cognitive function, but both cognitive impairment and sleep problems increase with normal aging. This study explored how sleep duration affects cognitive performance among older adults in China.MethodsUsing data from the Chinese Longitudinal Healthy Longevity Survey (CLHLS) in 2014 and 2018, cognitive function was assessed via the Mini-Mental State Examination (MMSE), which included five domains: orientation, registration, attention or calculation, recall, and language. Logistic regression was used to examine whether the change in sleep duration was a risk factor for cognitive impairment. We also used multinomial logistic regression to study the impact of sleep duration and the changes in sleep duration on cognitive changes during the follow-up period.ResultsThe empirical study showed a U-shaped relationship between sleep duration and increased risk of cognitive impairment. Short (< 6 hours) and long (> 8 hours) sleep durations were positively associated with cognitive impairment. Tests of interactions between sleep duration and sleep quality showed that short sleep durations with fair sleep quality had an increased risk of cognitive impairment. Further, the participants were divided into three groups: normal cognition (MMSE > 24), mild cognitive impairment (MCI, 18 ≤ MMSE score ≤ 24), and severe cognitive impairment (MMSE < 18). First, of the participants with normal cognition at baseline, those who sleeping > 7 h at follow-up and > 7 h at both baseline and 4-year follow-up assessments could increase the risk of cognitive impairment. Second, for individuals with MCI at baseline, those who transitioned to sleeping > 7 h at follow-up period and > 7 h at both baseline and 4-year follow-up assessments had a lower chance of reverting to normal cognition.ConclusionExcessive sleep may be a major risk for cognitive impairment among older adults. Furthermore, a moderate amount of sleep could be a possible strategy to prevent cognitive impairment.

Longitudinal associations between the frequency of playing Mahjong and cognitive functioning among older people in China: evidence from CLHLS, 2008–2018

“…Specifically, games like Mahjong, are considered to improve memory accuracy and reaction ability ( 29 , 67 ). Our research findings align with these previous studies ( 29 , 32–35 ). Moving to the data from 2011, older people who played Mahjong not only exhibited higher scores in attention and calculation but also demonstrated higher scores in language, understanding, and self-coordination.…”

“…The Mini-Mental State Examination (MMSE), also known as the Mini-Mental State Exam or the Simple Mental State Examination, was developed by Folstein et al in 1975 ( 31 ). The questionnaire encompasses an evaluation of five dimensions of cognitive function: general ability, reaction ability, attention and calculation abilities, recall capability, and self-coordination ability ( 32 ). It stands as one of the most influential standardized tools for assessing intellectual status.…”

Sleep state of the elderly population in Korea: Nationwide cross-sectional population-based study

“…In addition, this study confirmed that sleep quality was correlated with sociodemographic data such as sex, marital status, and education level. According to another recent nationwide cross-sectional study conducted in China, excessive sleep duration rather adversely affects the cognitive function of the elderly population ( 28 ). In addition, a US study of 25,962 people with an average age of 48.1 years concluded that sleep duration was independently associated with a high incidence of depression ( 29 ).…”

Association between cognitive dysfunction and diabetes in patients over 65 years old: a cross-sectional study using propensity score matching

“…The validity and reliability of this questionnaire have been validated in previous studies ( 17 , 18 ). Cognitive dysfunction in this study was defined using the criteria of Zhang et al ( 17 ) and Chen et al ( 19 ), whereby a MMSE score < 18 indicated cognitive dysfunction. Additional information regarding the MMSE scores of the participants is shown in Table SII .…”