Long Sleep Duration Associated With Cognitive Impairment in Chinese Community-Dwelling Older Adults

Relationship Between Sleep Duration and Cognitive Function in Older Adults: Analysis of NHANES and UK Biobank GWAS Data

OBJECTIVES

To explore the relationship between sleep duration and cognitive functions in older adults using NHANES, a national US population study dataset, and to explore the causal association with Mendelian randomization (MR) using the UK Biobank.

METHODS

First, an observational study was conducted with the NHANES database with participants ≥60 years. Sleep duration was measured with accelerometers for 7 consecutive days. Participants were divided into habitual short sleep (<7 h) and long sleep (>9 h) groups. Cognitive functions were measured with the CERAD Word Learning sub-set, Animal Fluency, and Digit Symbol Substitution test (DSST). Multivariate regression models were used to explore relationships between sleep duration and cognitive functions. Second, bidirectional MR was conducted with data for self-reported sleep duration, which came from a genome-wide association study (GWAS) comprising 446,118 adults from the UK Biobank, and general cognitive performance, which was obtained from a recent GWAS study (N = 257,841). Inverse-variance weighted (IVW) was used as the primary estimation of the outcome.

RESULTS

In the observational study, 2687 participants were included. Sleep duration was associated with cognitive functions in a non-linear way. Habitual long sleep (>9°h) was associated with lower scores on DSST (OR = 0.01, p = .003) in the fully-adjusted model. The association between habitual short sleep and cognitive functions was insignificant. For the MR, genetically predicted lower general cognitive performance was causally associated with a higher prevalence of habitual short sleep (OR = 0.97, p = 5.1 × 10-7) and long sleep (OR = 0.97, p = 8.87 × 10-16).

DISCUSSION

Short and long sleep duration might be both causally associated with worse outcomes of cognitive functions in older adults, highlighting the importance of maintaining sleep health.

Association between dependency and long sleep duration among elderly people: a community-based study

BACKGROUND

Long sleep duration is a common sleep disorder among elderly people. Dependency increases with increasing age. This study aimed to assess the association between dependency and long sleep duration among elderly people.

METHODS

This study is a population-based cross-sectional study. A total of 1152 participants aged ≥ 60 years were selected from 26 locations in China by a complex multistage sampling design. Data were collected through face-to-face interviews. Sleep duration was measured using the Pittsburgh Sleep Quality Index. Dependency was assessed using Minnesota Multiphasic Personality Inventory-II. Hierarchical multiple linear regression analysis was used to evaluate the efficacy of sleep-related factors and psychological factors for sleep duration. Analysis of covariance and logistic regression analysis were performed to evaluate the association between the dependency score and sleep duration, and the strength of dependency effect on sleep duration.

RESULTS

A total of 1120 participants were valid for the analysis. Among them, 15.8% of participants had a dependency score ≥60 points. The results of hierarchical multiple linear regression analysis showed that sleep duration was positively associated with dependency scores. Analysis of covariance indicated a J-shaped association between dependency scores and sleep duration. The results of logistic regression analysis showed dependency was significantly associated with long sleep duration, and the odds ratio was 3.52 (95% CI, 1.87-6.63; P < 0.001).

CONCLUSION

Dependency was significantly associated with long sleep duration among elderly people. The results suggested that dependent intervention may be a strategy that needs urgent implementation to reduce long sleep duration among elderly people.

Gender differences in the modifying effect of living arrangements on the association of sleep quality with cognitive function among community-dwelling older adults: a cross-sectional study

Background

Sleep quality is considered to be associated with cognitive function for older adults, but little is known about whether living with others can buffer mild cognitive impairment in older adults with poor sleep quality. The objective of this study was to examine the role of living arrangements in sleep quality and cognitive function among older adults aged 65 and over.

Methods

2,859 older adults over 65 years old were selected by using multi-stage stratified sampling method. Cognitive function and sleep quality were measured using Mini-Mental State Examination (MMSE) and Pittsburgh Sleep Quality Index (PSQI). Binary logistic regression was performed to examine the relationship between sleep quality and mild cognitive impairment, and the interaction effects of sleep quality and living arrangements on mild cognitive impairment stratified by gender.

Results

Poor sleep quality was associated with mild cognitive impairment among men and women regardless of living arrangements. The significantly protective role of living with others in reducing the incidence of mild cognitive impairment was found in men with poor sleep quality, but not in women.

Conclusion

Targeted support for older adults with poor sleep quality may be effective in preventing mild cognitive impairment, and gender differences should be taken into account when promoting cohabitations.

Longitudinal Relationship Between Frailty and Cognitive Impairment in Chinese Older Adults: A Prospective Study

We aimed to examine the longitudinal association between frailty and cognitive impairment in the older Chinese population. This prospective cohort study used data from the Chinese Longitudinal Healthy Longevity Study 2011 wave. We calculated the follow-up duration as 3 years from the baseline year. Frailty was measured using the frailty index, and cognitive function was calculated by Mini-Mental State Examination Scale. Participants who were non-frailty and those with normal cognitive function were included in 2011 and followed up in 2014, respectively. Frailty was an independent risk factor for early-onset cognitive impairment. Age, hearing impairment, and a decreased ability to perform daily activities were the main risk factors for cognitive impairment, while affluent economic status was a protective factor. Cognitive impairment was not found to be an independent risk factor for frailty. We concluded that the frailty index is a significant predictor of cognitive impairment among community-dwelling older adults.

Association between walking speed and cognitive domain functions in Chinese suburban-dwelling older adults

Objective

To examine the relationship among walking speed, cognitive impairment, and cognitive domain functions in older men and women living in a Chinese suburban community.

Methods

In total, 625 elderly (72.54 ± 5.80 years old) men (n = 258) and women (n = 367) from the Chongming district of Shanghai participated in this study. All participants had Mini-Mental State Examination (MMSE), 4-m walking test, medical history questionnaire, and physical examination. They were grouped according to walking speed (&gt;0.8 vs. ≤ 0.8 m/s) with the stratification of sex. The odds ratio (OR) and the 95% confidence interval (CI) were assessed using the chi-square test and logistic regression analysis.

Results

Around 11.6% of men and 14.2% of women had slow walking speeds. After adjusting for age, body mass index (BMI), education level, spouse, faller, the Geriatric Depression Scale (GDS) score, heart disease, stroke, arthritis, and low back pain, walking speed was negatively related to cognitive impairment in men (OR 0.11 [95% CI: 0.01, 0.94]; p = 0.043). In addition, the relationship between walking speed and impaired orientation was significant in both men (OR 0.003 [95% CI: 0.001, 0.05]; p &lt; 0.001) and women (OR 0.15 [95% CI: 0.03, 0.75]; p = 0.021).

Conclusion

The relationship between walking speed and cognitive impairment was only significant in men, but the association with impaired orientation was found in both men and women. Assessing the walking speed of the elderly is beneficial, which may help with early detection and early therapeutic prevention of cognitive impairment.

Association Between Pre-Stroke Subjective Sleep Status and Post-Stroke Cognitive Impairment: A Nationwide Multi-Center Prospective Registry

BACKGROUND

Although sleep disorders significantly increase the risk of cognitive impairment, literature is relatively scarce regarding the impact of sleep status on cognitive function in patients with acute ischemic stroke (AIS). We seek to study the association between pre-stroke subjective sleep status and cognitive function at 3 months after stroke.

PATIENTS AND METHODS

Data were analyzed for 1,759 AIS patients from the Impairment of Cognition and Sleep after Acute Ischemic Stroke or Transient Ischemic Attack in Chinese Patients Study (ICONS). Pre-stroke subjective sleep status was assessed by the Pittsburgh Sleep Quality Index (PSQI) and Epworth Sleepiness Scale (ESS). Greater sleep fragmentation was defined as waking up in the middle of the night or early morning ≥3 times a week. Cognitive function was evaluated using the Montreal Cognitive Assessment (MoCA) at 3 months after stroke. Primary endpoint was the incidence of post-stroke cognitive impairment (PSCI) at 3 months after stroke. The association between subjective sleep status and PSCI was evaluated using multivariable logistic regression.

RESULTS

PSCI occurred in 52.1% at 3 months after stroke. Patients with very bad sleep quality before stroke were at increased risk of PSCI (OR, 2.11; 95% CI, 1.11-4.03; P=0.03). Subgroup analysis found that the association between very bad sleep quality and PSCI was more evident among patients with high school education or above (OR, 5.73; 95% CI, 1.92-17.10; P for interaction=0.02). In addition, patients with greater sleep fragmentation before stroke were also at higher risk of PSCI (OR, 1.55; 95% CI, 1.20-2.01; P<0.01). Similarly, subgroup analysis showed that the risk of PSCI was more pronounced among patients without employment (OR, 2.45; 95% CI, 1.59-3.77; P for interaction=0.01).

CONCLUSION

Very bad sleep quality and greater sleep fragmentation before stroke were identified as independent risk factors for PSCI at 3 months after stroke.