Longitudinal impact of metabolic syndrome and depressive symptoms on subsequent functional disability among middle-aged and older adults in China

The mediating effect of depressive symptoms on the association between childhood friendship and physical function in middle-aged and older adults: Evidence from the China Health and Retirement Longitudinal Study (CHARLS)

BACKGROUND

This study examines the extent to which depressive symptoms mediate the link between childhood friendship (CF) and physical function among middle-aged and older adults in China.

METHODS

China Health and Retirement Longitudinal Study (CHARLS) data were used; specifically, CHARLS life history survey (conducted from June 1-December 31, 2014) and follow-up health survey (conducted from July 1-September 30, 2015) data were used. The Sobel test, Bootstrap test and multivariable logistic regression were performed to examine the mediating role of depressive symptoms (measured by the 10-item Center for Epidemiologic Studies Depression Scale) in the association between CF (measured by a standardized retrospective questionnaire) and physical function, which was measured by basic activities of daily living (BADL) disability, instrumental activities of daily living (IADL) disability, and grip strength.

RESULTS

A total of 12,170 participants aged 45 years or older were included in this cross-sectional study. After controlling for covariates, low-quality CF was associated with an increased prevalence of BADL disability (OR = 1.18; 95 % CI = 1.05-1.32), IADL disability (OR = 1.25; 95 % CI = 1.12-1.40), and low grip strength (OR = 1.21; 95 % CI = 1.09-1.34). The proportion of the mediating effect of depressive symptoms was 48 % for CF and BADL, 40 % for CF and IADL, and 11 % for CF and grip strength. Depressive symptoms and worse CF have a joint effect on BADL disability (OR = 3.30; 95 % CI = 2.82-3.85), IADL disability (OR = 3.52; 95 % CI = 3.03-4.09), and low grip strength (OR = 1.65; 95 % CI = 1.43-1.92).

LIMITATIONS

Not all potential confounding factors (such as childhood behavioural problems, genetic factors, and memory function) were measured in the analysis, and there may have been recall bias in the retrospective collection of CF data.

CONCLUSIONS

Individuals with high-quality CF were more likely to have a decreased prevalence of impaired physical function in later life. Depressive symptoms acted as a mediator associated with the development of CF.

Estimating the joint effect of household solid fuel use and social isolation on depression among middle-aged and older adults in China

BACKGROUND

Household solid fuel use and social isolation are reported to increase the risk of depressive symptoms, but their joint effect has not yet been examined. This study aimed to explore the separate and joint effects of household solid fuel use and social isolation on depression.

METHODS

We used data from the latest four waves (2011-2018) of the China Health and Retirement Longitudinal Study (CHARLS). Depression was defined as a score of ≥12 using the Center for Epidemiologic Studies Depression Scale (CES-D 10). Cox proportional hazards models were applied to explore the separate and joint associations of household solid fuel use and social isolation with incident depression.

RESULTS

During the seven-year follow-up, 2793 (30.25 %) out of the 9232 participants were identified with depressive symptoms. Solid fuel use for household heating or cooking was significantly associated with more hazards of depressive symptoms after adjusting for potential confounders (cooking: HR = 1.280, 95 % CI = 1.175-1.394; heating: HR = 1.142, 95 % CI = 1.054-1.238). High social isolation at baseline was also a significant predictor of incident depressive symptoms (HR = 1.139, 95 % CI = 1.053-1.231). Participants exposed to both solid fuel use and high social isolation were found to have higher hazards of experiencing depressive symptoms than those exposed to none or only one of these two risk factors (heating: HR for 'solid fuel use + high social isolation'=1.308 versus HR for other groups = 1-1.185; cooking: HR for 'solid fuel use + high social isolation' = 1.430 versus HR for other groups = 1-1.255).

CONCLUSION

Household solid fuel use and social isolation were separately and jointly associated with higher risks of incident depression. Appropriate interventions to reduce solid fuel use and social isolation are recommended to improve the psychological health among middle-aged and older adults in China.

Economic development, weak ties, and depression: Evidence from China

OBJECTIVES

Weak ties are becoming mainstream in daily relationships and play an essential role in the improvement of individuals' mental health. Despite growing concerns on depression, inclusion of weak ties is limited. To address the gap, this study empirically shed light on the role of weak ties on individual depression in the context of economic development.

METHOD

A cross-sectional study was conducted based on 2018 China Health and Retirement Longitudinal Study (CHARLS) with a sample of 16,545 individuals. A moderated mediation model is constructed to evaluate the impact of economic development (GDP) on the degrees of depression, the mediating effect of weak ties, and the moderating effect of residents' residence types (living in urban or rural areas).

RESULTS

Economic development exerts a significant direct impact on depression (β=-1.027, p<0.001). Weak ties are significantly negatively correlated with depression (β=-0.574, p<0.001), and act as a mediator between economic development and local individual depression. In addition, the residence type plays a moderating role between economic development and weak ties (β=0.193, p<0.001). That is, living in urban areas would introduce the higher the level of weak ties.

CONCLUSIONS

Higher economic development is largely conducive to alleviating the degrees of depression, weak ties play a mediating role in economic development and depression, and residence types have a positive moderating effect on the economic development and weak ties.

The Mediating Role of Depression in Association Between Total Sleep Time and Instrumental Activities of Daily Living in China

Objectives: This study aims to investigate the mediating role of depression and the moderating effect of gender in the relationship between total sleep time (TST) and instrumental activities of daily living (IADL) in middle-aged and elderly people (aged 45 or above).

Methods: The data used in this study is from the China Health and Retirement Longitudinal Study (CHARLS), including a total of 10,460 respondents. Associations between TST, IADL, depression, and gender were analyzed using logistic regression and Karlson, Holm, and Breen (KHB) methods.

Results: Short (OR = 1.42, 95% CI = 1.28–1.58 of ≤6 h) and long TST (OR = 1.16, 95% CI = 1.02–1.32 of 8–9 h; OR = 1.35, 95% CI = 1.19–1.54 of &gt;9 h) were both associated with IADL. The mediation effect analyses observed that depression explained 64.80% of the total effect of short TST (≤6 h) and IADL, but was insignificant in long TST (8–9 h and &gt;9 h). Meanwhile, gender has moderating effects on the mediation effect model.

Conclusion: The study suggests that health interventions that focused on the dimensions of TST and depression are crucial for preventing functional disability while accounting for gender differences.

The longitudinal association of remnant cholesterol with diabetes in middle-aged and elderly Chinese: A nationwide population-based cohort study

BACKGROUND AND AIMS

The association between remnant cholesterol (RC) and diabetes remains unclear in Chinese.

METHODS AND RESULTS

We used the data of 9464 Chinese adults aged ≥45 years from the China Health and Retirement Longitudinal Study (CHARLS). Estimated RC level was calculated as total cholesterol minus high-density lipoprotein cholesterol minus low-density lipoprotein cholesterol. Cox proportional hazard models and restricted cubic spline models were used to assess the relationships between RC and diabetes.

RESULTS

After 6 years of follow-up, a total of 777 respondents experienced new-onset diabetes. In multivariable-adjusted analyses, the adjusted hazard ratios (95 % confidence intervals) for the highest versus lowest quartile of RC was 1.45 (1.19-1.75) for risk of diabetes, and each 1-SD increase of RC (19.52 mg/dl) was associated with 9 % (HRs = 1.09; 1.03-1.15) increased risk of diabetes. There were also significant linear associations between RC level and diabetes (P for linearity <0.001).

CONCLUSION

Elevated RC levels were positively associated with increased risk of diabetes in Chinese adult population, suggesting that RC could be considered as a preferential predictor and treatment target of diabetes in Chinese population. Future prospective studies are needed to verify our findings and to assess the effect of RC-lowering interventions in diabetes prevention.