U-shaped association between sleep duration and subjective cognitive complaints in Chinese elderly: a cross-sectional study

The effect of childhood social isolation on behavioral cognition in Chinese middle-aged and older adults: The moderating effect of family support

INTRODUCTION

This study aimed to analyze the association of childhood social isolation and behavioral cognition, and moderating effect of family support in middle-aged and older adults.

METHODS

The study samples were from the China Health and Retirement Longitudinal Study (CHARLS) of 2014 and 2018. The dependent variable was behavioral cognitive ability, measured by episodic memory and mental state; The independent variable was childhood social isolation, and the moderating variable was family support. The baseline OLS regression model was used to explore the correlation among independent variables, dependent variables and moderating variables, the least square regression model was used to analyze the moderating effect of family support, and the replacement model and the method of replacing characteristic variables were used for the robustness test. Hierarchical regression heterogeneity analysis was performed to further verify the results of the moderating effect.

RESULTS

In this study, 3459 samples were selected for analysis. OLS baseline regression results showed that the deepening of childhood social isolation was significantly correlated with the decline of behavioral cognitive ability in middle-aged and elderly people (β=-0.9664, t = 0.0893). After adding all covariates, we found that childhood social isolation was significantly negatively correlated with behavioral cognitive ability in middle-aged and elderly people (β=-0.4118, t = 0.0785). Among the moderating variables of family support, we found that there is a moderating effect on female guardians' efforts of caring in early parental support (β=0.0948, t = 0.0320) and the frequency of children's visits in late children support (β=0.0073, t = 0.0036). Finally, through the heterogeneity test, we found that there were differences in the relationship between childhood social isolation and behavioral cognitive ability among middle-aged and elderly people of different ages, genders and places of residence. Moreover, there are significant differences in the moderating effect of female guardian's effort of caring and the frequency of children's visits in heterogeneous groups.

CONCLUSIONS

The greater the degree of childhood social isolation experienced by middle-aged and elderly people, the worse their behavioral cognitive ability. Female guardian's effort of caring and the frequency of children's visits have a moderating effect to suppress this negative effect.

Longitudinal associations between sleep duration and cognitive impairment in Chinese elderly

BACKGROUND

Age-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.

METHODS

Using 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.

RESULTS

The 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.

CONCLUSION

Excessive 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.

Sleep disturbance is associated with mild cognitive impairment: a community population-based cross-sectional study

BACKGROUND

Sleep is conducive to the elimination of brain metabolites and the recovery of brain function. However, the relationship between sleep disturbance and Mild Cognitive Impairment is not fully been determined.

METHODS

This was a community population-based cross-sectional study. A total of 1,443 participants from a village in the suburbs of Xi'an, China were enrolled in 2017. Sleep quality was evaluated using the Pittsburgh sleep quality index (PSQI), and sleep disturbance was defined as a PSQI score > 5. Mini-Mental State Examination (MMSE) was used to assess cognitive function and Mild Cognitive Impairment(MCI) was defined as the MMSE score less than cutoff values and meets the diagnostic criteria. Univariate and multivariate analyses were used to analyze the relationships between sleep disturbance and MCI.

RESULTS

Among 1,443 subjects, 69(4.78%) had MCI, and 830 (57.52%) had sleep disturbance. In bivariate analysis, MCI was associated with sleep disturbance (ρ = 0.094, P<0.001). In the binary logistic regression, MCI was positively associated with the sleep disturbance (OR = 2.027, 95%CI = 1.112-3.698, P = 0.021). In the internal constitution of PSQI, MCI was negatively associated with the habitual sleep efficiency (OR = 0.447, 95%CI = 0.299-0.669, P < 0.001). Compared with waking up before or at 7 am, waking up after 7 am (OR = 0.555, 95%CI = 0.309-0.995, P = 0.048), or 8 am (OR = 0.296, 95%CI = 0.097-0.902, P = 0.032) was probably more likely to have normal cognition. However, people who slept more than 8 h a day might be more likely to suffer from MCI (OR = 5.560, 95%CI = 1.419-21.789, P = 0.014).

CONCLUSION

Sleep disturbance is associated with Mild Cognitive Impairment. However, the causal relationship between them is not clear. It needs to be further studied.