Latent variable analyses of age trends of cognition in the Health and Retirement Study, 1992-2004

Mediation analysis of cognitive function in the relationship between pulmonary function and depression among middle-aged and older adults

AIM

This study aims to explore the association between declining lung function and depression in middle-aged and older adults, with a special focus on the mediating role of cognitive function.

METHODS

This study utilizes self-reported and physical examination data from 5345 individuals participating in the 2015 cycle of the China Health and Retirement Longitudinal Study (CHARLS) to explore the role of cognitive function changes in mediating the effects of diminished lung function on depression among middle-aged and older adults.

RESULTS

Multivariate linear regression analysis revealed a positive correlation between pulmonary and cognitive functions (β = 0.003, 95% CI: 0.002∼0.003, P < 0.01) and a negative correlation between cognitive function and depression (β = -0.279, 95% CI: -0.330-0.228, P < 0.01). Cognitive function plays a mediating role in linking pulmonary function with depression, exhibiting a mediation effect of -0.0007 and a total effect of -0.0046, wherein the mediation effect contributes to 15.22% of the total effect. For females, the mediating effect of cognitive function was stronger (β = -0.0013, 95% CI: -0.0018∼-0.0008, P < 0.01) than it was for males (β = -0.0006, 95% CI: -0.0009∼-0.0003, P < 0.01).

CONCLUSIONS

The study underscores the importance of monitoring lung and cognitive functions as interconnected factors contributing to the mental health of middle-aged and older adults. It suggests that interventions aimed at improving pulmonary health and cognitive function may help mitigate depressive symptoms among middle-aged and older adults. Further research is warranted to validate these findings across diverse cultural and demographic settings. Geriatr Gerontol Int 2024; 24: 1210-1217.

Associations between the Number of Children, Depressive Symptoms, and Cognition in Middle-Aged and Older Adults: Evidence from the China Health and Retirement Longitudinal Study

Background: China's rapidly aging population presents challenges for cognitive health and mental well-being among the older adults. This study examines how the number of children affects cognitive function in middle-aged and older adults and whether depressive symptoms mediate this relationship. Methods: This study analyzed data from waves 1 to 5 (2011-2020) of the China Health and Retirement Longitudinal Study (CHARLS), involving 5932 participants aged 45 and older. Participants were grouped by the number of children: childless, only child and multiple children. We used Logarithmic Generalized Linear Models (LGLMs) to explore the relationships among the number of children, depressive symptoms, and cognitive function. Indirect effect coefficients and 95% bias-corrected and accelerated confidence intervals (BCaCI) were estimated using Simultaneous Equation Models (SEM) with three-stage least squares (3SLS) and the bootstrap method to assess the mediating effect of depressive symptoms. Results: In middle-aged and older adults, a negative association was observed between the number of children and overall cognitive functioning (all p < 0.01). This association remained significant even after adjusting for covariates in groups with three (β = -0.023, p < 0.05) and four or more children (β = -0.043, p < 0.001). Conversely, the positive association between the number of children and depression also persisted after adjusting for covariates, although it weakened as the number of children increased (all p < 0.01). Depressive symptoms consistently correlated negatively with overall cognitive function (p < 0.001) and partially mediated the relationship between the number of children and cognitive function (pMe = 20.36%, p < 0.05). The proportion of the mediating effect attributed to depression was more pronounced in middle-aged and older adults who had experienced the loss of children (pMe = 24.31%) or had two children (pMe = 25.39%), with stronger mediating effects observed in males (pMe = 48.84%) and urban residents (pMe = 64.58%). Conclusions: The findings indicate that depressive symptoms partially mediate the relationship between the number of children and cognitive function in middle-aged and older adults in China. These results highlight the significance of considering mental health factors when studying cognitive function in this demographic. Notably, in families without children and those with two children, depressive symptoms play a crucial role in explaining the decline in cognitive function.

A Cross-Lagged Panel Analysis of Social Participation in the Relationship Between Functional Limitations and Cognitive Functioning: Evidence From CHARLS

Functional limitations refer to the dependency to perform activities of daily living. Increasing evidence has demonstrated a bidirectional association between functional limitations and cognitive functioning, although the exact mechanism remains unclear. This study investigated whether social participation bidirectionally mediates the association between functional limitations and cognitive decline. We analyzed a sample of 16,385 middle-aged and older adults (aged over 50 years) using longitudinal data from the China Health and Retirement Longitudinal Study (CHARLS; Waves 1-4). We utilized a cross-lagged panel model to examine the bidirectional mediation of social participation between functional limitations and cognitive functioning over a span of eight years. The results indicated that social participation bidirectionally and partially mediated the relationship between the onset of functional limitations and cognitive decline, indicating that social participation may play an important role in mitigating the disablement process.

Cognitive impairment and depression precede increased HDL-C levels in middle-aged and older Chinese adults: cross-lagged panel analyses

BACKGROUND

High-density lipoprotein cholesterol (HDL-C) is widely recognized for its protective effects against cognitive decline. However, recent studies have presented conflicting results, with some suggesting no significant cognitive benefits or even an increased risk of dementia associated with high HDL-C levels. For those who suffer from depression, the cognitive benefits of HDL-C may be diminished or reversed. The purpose of this study is to investigate the associations between HDL-C, cognitive ability, and depressive symptoms in middle-aged and older Chinese adults.

METHODS

The datasets utilized were sourced from the China Health and Retirement Longitudinal Study (CHARLS) for the years 2011 and 2015, comprising 4,302 participants. Cross-lagged models were employed to explore the temporal sequence between cognitive performance and HDL-C levels, and to examine the interplay among depression, cognition, and HDL-C. Confounding factors such as sociodemographic characteristics, sleep conditions, and history of chronic diseases were controlled for.

RESULTS

The analysis revealed unidirectional effects of baseline impaired cognition and greater severity of depression on increased HDL-C levels at follow-up (β =  - 0.036 and β = 0.028, respectively, P < 0.05). However, higher baseline HDL-C levels did not significantly predict cognitive performance or depression 4 years later (β =  - 0.008 and β = 0.023, respectively, P > 0.05). Depressive symptoms and cognition were found to have a significant bidirectional association (β =  - 0.026 and β =  - 0.053, respectively, P < 0.05).

CONCLUSIONS

Cognitive impairment and depression are associated with higher HDL-C levels, whereas higher HDL-C levels do not appear to protect against cognitive decline or depressive symptoms. These findings underscore the importance of preserving cognitive and mental health, which may lower the likelihood of cardiovascular disease and dementia. Future studies should validate these findings and develop targeted interventions tailored to specific populations.

Association of handgrip strength asymmetry and weakness with cognitive function: a nationally representative cohort study

OBJECTIVE

To describe the association of handgrip strength asymmetry and weakness with cognitive function among Chinese middle-aged and older adults.

STUDY DESIGN

We used data from four waves (2011, 2013, 2015, and 2018) of the China Health and Retirement Longitudinal Study. Handgrip strength was measured at baseline. Handgrip strength asymmetry was defined on the basis of the ratio of handgrip strength of the non-dominant hand to that of the dominant hand (i.e. non-dominant/dominant): a ratio of <0.9 defined as dominant handgrip strength asymmetry and >1.1 as non-dominant handgrip strength asymmetry. Weakness was defined as a handgrip strength of <28 kg for males or <18 kg for females.

MAIN OUTCOME MEASURES

Cognitive function with its two core dimensions (episodic memory and mental status) at each wave was assessed and standardized.

RESULTS

9333 participants (48.3 % female, age 58.2 ± 9.0 years) were included. Non-dominant but not dominant handgrip strength asymmetry was significantly associated with poorer cognitive function at baseline (β = -0.121, -0.092, and -0.132 for mental status, episodic memory, and global cognition, respectively). In longitudinal analyses over 2 years, dominant handgrip strength asymmetry significantly slowed cognitive decline (β = -0.078 and -0.069 for mental status and global cognition, respectively), and non-dominant handgrip strength asymmetry accelerated cognitive decline (β = 0.053 and 0.043 for episodic memory and global cognition, respectively). Weakness was associated with poorer cognitive function at baseline and cognitive decline over 2, 4, and 7 years (all P < 0.05).

CONCLUSIONS

In middle-aged and older adults, non-dominant handgrip strength asymmetry and weakness were associated with poorer cognitive function and predicted accelerated cognitive decline. Dominant handgrip strength asymmetry may be beneficial for maintaining cognitive function.

Health Care Access and Cognitive Function in Older Adults: A Cross-Lagged Panel Longitudinal Analysis

Objective: The current longitudinal study examined how (1) cognitive measures, including episodic memory, executive function, and global cognition, predict later healthcare access and how (2) healthcare access predicts later cognition. Methods: Drawing a sample (n = 9920) from the Health and Retirement Study dataset, we created a cross-lagged panel model to examine the longitudinal association between cognitive measures and healthcare access from 2012 to 2018. Results: Results revealed that cognitive measures significantly predict later healthcare access, with effects increasing across waves. However, within sub-domains, memory was more predictive of later healthcare access over time compared to executive function. Discussions: Our study suggested an increased link between cognition and healthcare access during aging. Even outside of the context of AD, there are likely both policy-based and practical implications to ensure those experiencing cognitive decline continue to maintain access to care.

WeChat usage and preservation of cognitive functions in middle-aged and older Chinese adults: indications from a nationally representative survey, 2018-2020

PURPOSE

To investigate the associations between the most popular social media platform WeChat usage and cognitive performance among the middle-aged and older Chinese population using data from a nationally representative survey.

METHODS

In total, 17,472 participants (≥ 45 years old) from the China Health and Retirement Longitudinal Study (CHARLS, Wave 4, 2018) were analyzed. Cognitive performance including episodic memory and executive function was assessed using Mini-Mental Status Examination (MMSE). Other confounding variables included socio-economic characteristics, medical status, and lifestyle-related information. Multiple linear regression models were used to test the association between cognitive performance and WeChat usage by introducing covariates hierarchically. Subgroup analyses of age and gender were conducted to estimate the robustness of the primary findings.

RESULTS

After adjusting for multiple confounders across all linear models, WeChat usage is significantly associated with executive function, episodic memory, and global cognitive performance (all p values<0.05). Such results remained robust in subgroup analyses, stratified by age and gender, and also verified according to longitudinal analyses. Compared to 'Chat-only' users who only used WeChat for online interpersonal communication, further usage of WeChat functions such as using 'Moments' appeared to be significantly associated with better cognitive performance, especially for episodic memory.

CONCLUSION

Social media usage is significantly and positively associated with better cognitive performance among the middle-aged and older Chinese population. Along with point-to-point messaging, using 'Moments' and extended social media platform functions may correlate to better cognitive performance.

Parent-Child Relationship Typologies and Associated Health Status Among Older Adults in the United States and China: A Cross-Cultural Comparison

Background and Objectives

Cultural differences in intergenerational relationships have been well established in prior research. However, cross-national comparison evidence on the parent-child relationship and its health implications remains limited.

Research Design and Methods

Data from the 2014 U.S. Health and Retirement Study and the 2015 Health and Retirement Longitudinal Study in China were used (N US, non-Hispanic Whites only = 3,918; N China = 4,058). Relationship indicators included coresidence, living nearby, having weekly contact, receiving assistance with daily activities, providing grandchild care, and financial transfer to/from children. Latent class and regression analyses were conducted.

Results

Four classes were identified for non-Hispanic White older Americans: (1) distant and uninvolved (6.58%), (2) geographically proximate with frequent contact and downward support (47.04%), (3) coresident with frequent contact and upward support (13.1%), and (4) geographically proximate with frequent contact (33.28%). Three classes were identified among older Chinese: (1) coresident with frequent contact and upward support (37.46%), (2) coresident/interdependent (25.65%), and (3) geographically proximate with frequent contact and upward financial support (36.89%). For non-Hispanic White older Americans, providing downward support was associated with fewer functional limitations and better cognition. Receiving instrumental support from children was associated with more depressive symptoms, more functional limitations, and poorer cognition among older Chinese.

Discussion and Implications

Cultural contrasts were evident in parent-child relationship typologies and their health implications. Compared to the U.S. non-Hispanic Whites, parent-child relationships in China tended to be closer and associated with poorer health status. The findings call for culturally relevant strategies to improve parent-child relationships and ultimately promote the health of older adults.

Associations Between Self-Reported Visual Difficulty, Age of Onset, and Cognitive Function Trajectories Among Chinese Older Adults

Objectives: This study examined the association between self-reported visual difficulty and age-related cognitive declines among older Chinese adults and how the timing of visual difficulty onset plays a role in cognitive trajectories. Methods: Data were drawn from the 2011-2018 wave of the China Health and Retirement Longitudinal Study, involving 9974 respondents aged 60 years or older (mean age 65.44 years, range 60-101 years). Results: At baseline, 14.16% respondents had self-reported visual difficulty. Growth curve models showed that Chinese older adults with visual difficulty experienced a faster decline in cognitive function compared to those without visual difficulty (β = -0.02, p < .01). Older adults who began experiencing visual difficulty between 61 and 75 years of age had steeper cognitive declines compared to those with earlier or later onset (β = -0.05, p < .01). Discussion: Older adults with self-reported visual difficulty experience faster rates of cognitive decline. Future research should explore potential factors that underlie the association between onset timing of visual difficulty and cognitive function.

Race, Educational Attainment, and Sustained High Body Mass Index over 24 Years of Follow-up in Middle-Aged and Older Adults

BACKGROUND

Educational attainment has been linked to reduced risk of health problems such as obesity, but research suggests that this effect may be weaker for non-Hispanic Black individuals compared to non-Hispanic White individuals, a pattern known as minorities' diminished returns (MDRs).

OBJECTIVES

This study is aimed at examining the differential association between educational attainment and sustained high body mass index (BMI) among non-Hispanic Black and non-Hispanic White middle-aged and older adults in the USA.

METHODS

Using data from the Health and Retirement Study (HRS) spanning 1992-2016, we analyzed a national sample of 35,110 individuals, including 7766 non-Hispanic Black and 27,344 non-Hispanic White individuals. We used logistic regression models to examine the relationship between educational attainment, race, and sustained high BMI, while controlling for age, sex, and marital status at baseline.

RESULTS

Approximately 30.6% of the sample (n = 10,727) had sustained high BMI, while 69.4% (n = 24,383) had sustained low BMI over the period of follow-up. Higher levels of educational attainment were associated with a lower risk of sustained high BMI. We also found, however, that the protective effects of education against sustained high BMI were weaker for non-Hispanic Blacks compared to non-Hispanic Whites.

CONCLUSION

Our findings suggest that the protective effects of educational attainment against sustained high BMI may be more robust for non-Hispanic Whites than for non-Hispanic Blacks. Further research should explore whether these results are found in other racial and ethnic minorities and whether potential life history experiences may contribute to these disparities.

Association of prediabetes progression and regression with cognitive decline: Findings from the CHARLS

AIM

The aim of the study was to describe the association of prediabetes progression and regression with change in cognitive function.

METHODS

Data from three waves (2011, 2015 and 2018) of the China Health and Retirement Longitudinal Study (CHARLS) were analysed. Diabetic statuses in 2011 and 2015 were ascertained using the American Diabetes Association criteria. Cognitive function was assessed and standardized at all three waves, where a total score and its two components (episodic memory and metal status) were calculated. We evaluated the association of prediabetes progression and regression (from 2011 to 2015) with changes in cognitive function from 2011 to 2015 and from 2015 to 2018.

RESULTS

Of 2590 participants (56% women, mean age 58.6 ± 8.4 years) with prediabetes, 12% progressed to diabetes and 41% regressed to normoglycaemia. Compared with participants who remained as prediabetes, those who progressed to diabetes showed a trend to have accelerated decline in episodic memory (β = -0.11, 95% confidence interval -0.22 to 0.003, p = 0.057). However, participants who regressed to normoglycaemia did not have less cognitive decline. Neither prediabetes progression nor regression predicted change in cognitive function from 2015 to 2018. In a separate group of participants who remained as normoglycaemia (n = 858), changes in cognitive function from 2011 to 2015 and from 2015 to 2018 were similar to those who remained as prediabetes.

CONCLUSION

In people with prediabetes, progression to diabetes may be associated with accelerated cognitive decline but regression to normoglycaemia does not retard cognitive decline. Prediabetes progression and regression may not be predictive of change in cognitive function.

Association of social integration with cognitive function trajectories among Chinese older adults: evidence from the China health and retirement longitudinal study (CHARLS)

Background

The prevalence of cognitive impairment among older adults remains high. It has been proven that social integration is related to cognitive function. However, limited research has examined the association of social integration and its different dimensions with cognitive function trajectories of older adults.

Methods

The data were from the China Health and Retirement Longitudinal Study (CHARLS) spanning 2013 (T1) to 2018 (T3). A total of 3,977 older adults were included in the final analysis. Cognitive function was measured with items from an adapted Chinese version of the Mini-Mini-Mental Mental State Examination (MMSE), while the measurement of social integration included three dimensions: economic integration, relational integration and community integration. A group-based trajectory model (GBTM) was used to identify cognitive trajectory groups among participants and an unordered multinomial logistic regression was employed to explore the association of baseline social integration and its three dimensions with cognitive function trajectories.

Result

Three cognitive function trajectory groups were identified: low-decline group (24.1%), medium-decline group (44.2%) and high-stable group (31.7%). Comparing to the medium-decline trajectory group, older adults with higher social integration scores were more likely to be in the high-stable trajectory group (OR = 1.087, 95%CI: 1.007 ~ 1.174), while less likely to be in the low-decline group (OR = 0.806, 95%CI: 0.736 ~ 0.882). Among the different dimensions of social integration, older adults with higher community integration scores were more likely to be in the high-stable trajectory group (OR = 1.222, 95%CI: 1.026 ~ 1.456); Older adults with higher relational integration scores were less likely to be in the low-decline trajectory group (OR = 0.816, 95%CI: 0.734 ~ 0.906). The economic integration was not found to correlate with the cognitive function trajectories. Stratified analyses revealed that the association between community integration and cognitive trajectories was only significant among older adults aged 60 to 69, and the association between relational integration and cognitive trajectories was only significant among older adults who was agricultural household registration.

Conclusion

The developmental trajectories of cognitive function among Chinese older adults are heterogeneous. Social integration is significantly related to the trajectories of cognitive function in Chinese older adults. Measures should be taken to promote social integration of Chinese older adults to reduce the decline of cognitive function.

The association between sarcopenia and functional disability in older adults

OBJECTIVES

Sarcopenia is associated with functional disability in older adults. However, no consistent conclusions have been reached considering the differences in the measurement and criteria of sarcopenia. We aimed to examine the association between sarcopenia status and functional disability based on China Health and Retirement Longitudinal Study (CHARLS).

DESIGN

A nationally representative longitudinal study.

SETTING AND PARTICIPANTS

Participants aged at least 60 years old from the CHARLS 2015y were included.

MEASUREMENTS

Sarcopenia was assessed according to the Asian Working Group for Sarcopenia 2019 algorithm. The outcomes of this study were basic activities of daily living (ADLs) and instrumental activities of daily living (IADLs). The logistic regression model was conducted to analyze the cross-sectional and longitudinal associations between sarcopenia status and ADLs and IADLs disability.

RESULTS

In the cross-sectional study, 37.2% of the 6893 participants were defined as having sarcopenia. Any form of sarcopenia was associated with ADLs and IADLs disability. During three years of follow-up, 786 (16.5%) participants developed new-onset ADLs disability, and 980 (22.5%) participants developed new-onset IADLs disability. Compared with the no-sarcopenia, participants with possible sarcopenia (OR: 1.62, 95%CI: 1.34-1.95), sarcopenia (OR: 1.58, 95%CI: 1.18-2.11), or total sarcopenia (OR: 1.58, 95%CI: 1.34-1.88) had a higher risk of ADLs disability. While, the risk of IADLs disability for participants with possible sarcopenia (OR: 1.68, 95%CI: 1.41-2.00), sarcopenia (OR: 1.87, 95%CI: 1.40-2.51), or total sarcopenia (OR: 1.71, 95%CI: 1.45-2.00) was still significantly increased. With statistical interaction between sarcopenia status and residence or sex in ADLs and IADLs disability, older adults in urban, with ORs ranging from 2.14 to 2.44, were at a higher risk of functional disability than those in rural. Possible sarcopenia was associated with a much higher risk of ADLs disability (OR: 1.68, 95%CI: 1.26-2.25) in males and a higher risk of IADLs disability (OR: 1.98, 95%CI: 1.56-2.52) in females.

CONCLUSIONS

Sarcopenia was associated with an increased risk of ADLs and IADLs disability among older Chinese adults. Even possible sarcopenia still significantly impacted ADLs and IADLs disability, and this association varied by sex and residence.

Bidirectional associations between hearing difficulty and cognitive function in Chinese adults: a longitudinal study

Background

Middle-aged and older adults frequently experience hearing loss and a decline in cognitive function. Although an association between hearing difficulty and cognitive function has been demonstrated, its temporal sequence remains unclear. Therefore, we investigated whether there are bidirectional relationships between hearing difficulty and cognitive function and explored the mediating role of depressive symptoms in this relationship.

Method

We used the cross-lagged panel model and the random-intercept cross-lagged panel model to look for any possible two-way link between self-reported hearing difficulty and cognitive function. To investigate depressive symptoms' role in this association, a mediation analysis was conducted. The sample was made up of 4,363 adults aged 45 and above from the China Health and Retirement Longitudinal Study (CHARLS; 2011-2018; 44.83% were women; mean age was 56.16 years). One question was used to determine whether someone had a hearing impairment. The tests of cognitive function included episodic memory and intelligence. The Center for Epidemiologic Studies Depression Scale, which consists of 10 items, was used to measure depressive symptoms.

Results

A bidirectional association between hearing and cognition was observed, with cognition predominating (Wald χ2 (1) = 7.241, p < 0.01). At the between-person level, after controlling for potential confounders, worse hearing in 2011 predicted worse cognitive function in 2013 (β = -0.039, p < 0.01) and vice versa (β = -0.041, p < 0.01) at the between-person level. Additionally, there was no corresponding cross-lagged effect of cognitive function on hearing difficulty; rather, the more hearing difficulty, the greater the cognitive decline at the within-person level. According to the cross-lagged mediation model, depressive symptoms partially mediates the impact of cognitive function on subsequent hearing difficulty (indirect effect: -0.003, bootstrap 95% confidence interval: -0.005, -0.001, p < 0.05), but not the other way around.

Conclusion

These results showed that within-person relationships between hearing impairment and cognitive function were unidirectional, while between-person relationships were reciprocal. Setting mental health first may be able to break the vicious cycle that relates hearing loss to cognitive decline. Comprehensive long-term care requires services that address depressive symptoms and cognitive decline to be integrated with the hearing management.

Gender-specific moderating role of abdominal obesity in the relationship between handgrip strength and cognitive impairment

BACKGROUND & AIMS

Both low handgrip strength (HGS) and abdominal obesity (AO) are associated with cognitive impairment. However, it remains unclear whether low HGS and AO interact to affect cognition, and whether the synergistic effect varies by gender. This study aimed to examine whether the association between low HGS and incident cognitive impairment was moderated by AO among Chinese older men and women.

METHODS

We used the data of participants (≥60 years) from four waves (2011-2018) of the China Health and Retirement Longitudinal Study. We defined low HGS as the maximal HGS of <28 kg in men and <18 kg in women, and AO as waist circumference of ≥90 cm for men and ≥80 cm for women. Cognitive impairment was defined as a global cognitive score in the lowest 10th percentile. For each gender, we used subdistribution hazards model to estimate subdistribution hazard ratios (SHRs) for the association of low HGS and AO with incident cognitive impairment, treating mortality as the competing event and controlling for other covariates. Multiplicative interaction was assessed through a cross-product interaction term of low HGS and AO in the model. Additive interaction between low HGS and AO was evaluated by calculating the relative excess risk due to interaction (RERI) and attributable proportion due to interaction (AP).

RESULTS

We included 3704 participants (Mean age: 66.9 ± 5.81; 54.9% male). During the 7-year follow-up, 1133 events of interest occurred (731 cognitive impairments and 402 deaths). Incidence rates of cognitive impairment and mortality were 4.1 (95% CI: 3.8 to 4.4) and 2.2 (95% CI: 2.0 to 2.5) per 100 person-years. There were positive multiplicative (SHR for the product term = 1.974, 95% CI: 1.114 to 3.500) and additive interactions (RERI = 1.056, 95% CI: 0.027 to 2.086, AP = 0.454, 95% CI: 0.158 to 0.750) of low HGS and AO on the risk of cognitive impairment among older men. Male participants with both low HGS and AO showed an increased risk of cognitive impairment (SHR = 2.325, 95% CI: 1.498 to 3.609) compared with those without either. There was no evidence of interaction among older women (SHR for the product term = 1.151, 95% CI: 0.725 to 1.825; RERI = 0.044, 95% CI: -0.524 to 0.613; AP = 0.039, 95% CI: -0.458 to 0.536).

CONCLUSIONS

Low HGS and AO may interact to synergistically increase the risk of cognitive impairment among Chinese older men. Screening the highest-risk subpopulation, who may benefit most from neurocognitive prevention strategies, may maximize potential public health gains.

Education, Social Engagement, and Cognitive Function: A Cross-Lagged Panel Analysis

OBJECTIVES

Although education and social engagement are considered cognitive reserves, the pathway of both reserves on cognitive function has been rarely studied. This study aimed to examine the underlying mechanism between education, social engagement, and cognitive function.

METHODS

This study used 2-wave data (2010 and 2014) from Health and Retirement Study in the United States (N = 3,201). Education was measured by years of schooling. Social engagement was evaluated by 20 items including volunteering, physical activities, social activities, and cognitive activities. Cognitive function was assessed by a modified Telephone Interview for Cognitive Status. A cross-lagged panel model was fitted to test the mediating mechanism between education, social engagement, and cognitive function.

RESULTS

Controlling for covariates, higher education in early life was associated with better cognitive function in old age (b = 0.211, 95% confidence interval [CI] = [0.163, 0.259], p < .01). Late-life social engagement partially mediated the association between education and cognitive function (indirect effect = 0.021, 95% CI = [0.010, 0.033], p < .01). The indirect path between education and social engagement via cognition also existed (b = 0.009, 95% CI = [0.005, 0.012], p < .001).

DISCUSSION

Education in earlier life stage may exert a lifelong effect on cognitive function as well as an indirect effect via enhancing late-life cognitive reserve such as social engagement. The cross-lagged effect of social engagement on cognitive function is significant and vice versa. Future research may explore other cognitive reserves over the life course and its underlying mechanism to achieve healthy cognitive aging.

The relationship between physical activity, cognitive function and health care use: A mediation analysis

Physical activity is known to provide substantial health benefits and subsequently reduce health care use among older people, but little is known about how much of this effect is due to improved cognitive function as opposed to physical improvements in health. We study the direct and indirect effect of physical activity on health care use using the word recall task as a measure of cognitive function in a mediation framework. We use data from eight waves of the US Health and Retirement Study (HRS) (2004 - 2018) of people aged 65 and older and exploit genetic variations between individuals as an instrumental variable (IV) for cognitive function, a local health care supply measure as IV for health care use, and neighbourhood physical activity as IV for individual physical activity in our simultaneous three-equation model. We find small but negative direct and indirect effects of physical activity through improved cognitive function on the probability to see a GP and being admitted to a hospital, as well as the number of GP visits and the hospital length of stay. Improved cognitive function explains between 5% to 17% of the total effect of physical activity on the reduction in health care use.

Music Engagement and Episodic Memory Among Middle-Aged and Older Adults: A National Longitudinal Analysis

OBJECTIVES

The objective of this study was to examine associations between music engagement and episodic memory for more than 12 years in a nationally representative sample of middle- and older-aged adults in the United States.

METHODS

This study is based on a secondary analysis of data from a sample (N = 5,021) of cognitively normal adults from the Health and Retirement Study (2006-2018). Episodic memory was measured by immediate and delayed recall tasks. Music engagement was classified as none, passive (i.e., listening to music), active (i.e., singing and/or playing an instrument), or both (i.e., listening to music and singing or playing an instrument).

RESULTS

Compared with those with no music engagement, respondents who reported both passive and active engagement performed 0.258 points better at baseline on episodic memory tasks. This group also performed better across time with scores that declined by 0.043 points fewer per study visit. Additionally, compared to those with no music engagement, participants with passive music engagement had scores that declined by 0.023 points fewer per visit. There were no significant differences in performance at baseline for those with passive or active music engagement, or across time for those with active engagement.

DISCUSSION

The results of this study suggest that engaging in both passive and active music engagement may be superior to engaging with music only passively or actively and that engaging in music both ways may be able to protect against age-related declines in episodic memory. Future research should examine whether community-based music engagement interventions can affect this trajectory of decline.

New evidence of trends in cognitive function among middle-aged and older adults in China, 2011-2018: an age-period-cohort analysis

BACKGROUND

Increasing evidence from high-income countries suggests the risk of cognitive impairment has been declining recently. However, related studies in China have rarely been done, and the results are inconsistent. We analyze the trends in cognitive function among middle-aged and older adults in China between 2011 and 2018.

METHODS

We used data from four waves of the China Health and Retirement Longitudinal Study (CHARLS), including 48918 individuals aged 45 years and older. Cognitive function was assessed using the CHARLS cognitive measures containing episodic memory, orientation, attention, and visuospatial abilities. The hierarchical age-period-cohort (APC) model was used to quantify the separate age, period, and cohort effects on trends in cognitive function.

RESULTS

The study sample's ages ranged from 45 to 105 years (Mean = 59.2, SD = 9.4). Cognitive function declined with age net of period and cohort effects, an apparent acceleration in the rate of cognitive decline after age 65 was found adjusting for individual characteristics. Although period effects on trends in cognitive function remained stable during the study period, hierarchical APC models demonstrated significant cohort variations. Independent of age and period effects, there was a fluctuating trend across cohorts before 1960 and an overall decline across successive cohorts.

CONCLUSIONS

Our study indicates that the age effect remains the most crucial factor regarding cognitive decline. Moreover, results demonstrate that cohorts living in social upheaval leading to educational deprivation and/or nutritional deficiency in early life may face a higher risk for cognitive deterioration later in life. Such findings indicate that dementia prevention from a life course perspective and cohort-specific strategies are critical to alleviating the future public-health burdens related to cognitive aging. Ongoing attention should be paid to the role of cross-cohort differences in education on cohort trends in cognition in countries like China that are aging rapidly and have a late start in educational expansion compared to other countries. Other factors, such as environmental stimulation, need to be noticed in younger cohorts.

Understanding the Effects of Widowhood on Health in China: Mechanisms and Heterogeneity

This paper analyzes the impact of widowhood on the health of mid-aged and older individuals in China using data from the China Health and Retirement Longitudinal Study (CHARLS) data. Our results show that widowhood significantly increases the risk of depression, chronic diseases, and body pain while reducing cognitive function, sleeping time, and daily activity functions. The effects on depression and daily functions are immediate, that on chronic diseases is lagged, and the effects on cognitive function and sleeping hours persist over time. We find that rural widows are particularly vulnerable to negative health outcomes due to their weaker economic positions, for whom widowhood leads to more grandchild care responsibility and corresponding workforce and social withdrawals. Moreover, rural widows' income loss is not compensated by children, either by co-residence or financial transfers, leading to reduced living standards. Overall, our findings suggest that China needs to strengthen economic security for older people, especially among rural women, in order to avoid significant negative consequences of widowhood.

Age-Related Trajectories of General Fluid Cognition and Functional Decline in the Health and Retirement Study: A Bivariate Latent Growth Analysis

There have been few studies on associations between age-related declines in fluid cognition and functional ability in population-representative samples of middle-aged and older adults. We used a two-stage process (longitudinal factor analysis followed by structural growth modeling) to estimate bivariate trajectories of age-related changes in general fluid cognition (numeracy, category fluency, executive functioning, and recall memory) and functional limitation (difficulties in daily activities, instrumental activities, and mobility). Data came from the Health and Retirement Study (Waves 2010-2016; N = 14,489; ages 50-85 years). Cognitive ability declined on average by -0.05 SD between ages 50-70 years, then -0.28 SD from 70-85 years. Functional limitation increased on average by +0.22 SD between ages 50-70 years, then +0.68 SD from 70-85 years. Significant individual variation in cognitive and functional changes was observed across age windows. Importantly, cognitive decline in middle age (pre-age 70 years) was strongly correlated with increasing functional limitation (r = -.49, p < .001). After middle age, cognition declined independently of change in functional limitation. To our knowledge, this is the first study to estimate age-related changes in fluid cognitive measures introduced in the HRS between 2010-2016.

Longitudinal associations between specific types/amounts social contact and cognitive function among middle-aged and elderly Chinese: A causal inference and longitudinal targeted maximum likelihood estimation analysis

BACKGROUND

Social contact has demonstrated associations with cognitive function, while the literature on the effect of specific social relationship subdomains on cognitive function is limited. This study aimed to examine the causal effects of specific types/amounts of social contact on cognitive function among middle-aged and elderly Chinese.

METHODS

A total of 38,883 middle-aged and elderly adults from the China Health and Retirement Longitudinal Study were involved. Social contact in this study included interaction with families, taking care of grandchildren, interaction with friends, and participation in three types of social activities. We performed the linear mixed-effects model analysis with propensity score approach and the longitudinal targeted maximum likelihood-based estimation analysis after adjusting for potential covariates and confounders.

RESULTS

Interaction with families, caring for grandchildren, interaction with friends and participation in social activities were all associated with cognitive z-scores. Participants who interacted with families "2-3 times a week" and "once a week" versus "almost every day" had higher cognitive z-scores. Those who interacted with friends and participated in social activities "almost every week" versus "almost daily" had higher cognitive z-scores.

LIMITATIONS

The assessment of cognition was biased against people with poor education due to elements of language and mathematical testing, and against those with visual impairment.

CONCLUSIONS

Social contact was associated with better cognitive function among middle-aged and elderly Chinese. Social contact "1-3 times a week" was optimal for cognitive function. More social contact in middle-aged and elderly Chinese led to less cognitive decline in later life than in their inactive peers.

Association of spouse's health status with the onset of depressive symptoms in partner: Evidence from the China Health and Retirement Longitudinal Study

BACKGROUND

This study aimed to evaluate the associations between the multidimensional health status of one spouse and the onset of depressive symptoms in partner, and whether the associations differed by gender and residence.

METHODS

We analyzed data from 2401 females and their husbands (scenario 1), and 2830 males and their wives (scenario 2) who participated in the 2011/2012 and 2015 waves of China Health and Retirement Longitudinal Study. Depressive symptoms were assessed using the 10-item Centre for Epidemiological Studies Depression Scale. Multidimensional health indicators included mobility disability, activities of daily living disability, frailty, global cognition, depressive symptoms, comorbidity, and self-reported health. Principal component analysis was used to construct a composite health indicator reflecting overall health status that was then categorized into three groups (poor, moderate, and excellent). Logistic regression models were performed.

RESULTS

We observed strong associations of spouse's health status with the onset of depressive symptoms in partner. For instance, females whose husbands had poor overall health status reported more depressive symptoms than those having husbands with excellent overall health after four years (OR: 1.75; 95 % CI: 1.35, 2.26). These associations were statistically significant in rural females and urban males, but surprisingly disappeared in rural males and urban females.

LIMITATIONS

No exact timing of depressive symptoms onset.

CONCLUSIONS

In Chinese middle-aged and older adults, spouse's health status is associated with depressive symptoms in partner and the associations vary by gender and residence. The findings underscore the importance of considering partner's health status to manage one spouse's mental health.

Depressive Symptom Trajectories and Cognition Among Older American Couples: A Dyadic Perspective

OBJECTIVES

This study examined whether trajectories of depressive symptoms of one spouse are associated with the other spouse's memory.

METHODS

Longitudinal data from the Health and Retirement Study (2004-2016) were used (N = 5690 heterosexual couples). Latent-class growth analysis and structural equation models examined the actor and partner effects of depressive symptom trajectories on memory.

RESULTS

Four depressive symptom trajectories were identified (i.e., persistently low, increasing, decreasing, and persistently high). Compared to the low trajectory group, the increasing and persistently high trajectories were associated with worse memory for both men and women. While none of the wives' depressive symptom trajectories was significantly associated with husbands' memory (p > .05), husbands' decreasing trajectory was linked to wives' better memory (β = 0.498, 95% CI = 0.106, 0.890).

DISCUSSION

Older adults with increasing and persistently high depressive symptoms may experience worse memory. Psychosocial interventions targeting depressive symptoms among older men may be beneficial to their spouses' memory.

Shifting of Cognitive Assessments Between Face-to-Face and Telephone Administration: Measurement Considerations

OBJECTIVES

Telephone-administered cognitive assessments are a cost-effective and sometimes necessary alternative to face-to-face assessments. There is limited information in large studies concerning mode effects, or differences in cognition attributable to the assessment method, as a potential measurement threat. We evaluated mode effects on cognitive scores using a population-based sample of community-living older adults.

METHODS

We used data from participants aged 65-79 in the 2014 Health and Retirement Study for whom the interview mode was randomized (n = 6,825). We assessed mode differences in test means, whether mode modifies associations of cognition with criterion variables, and formal measurement invariance testing.

RESULTS

Relative to face-to-face assessment, telephone assessment was associated with higher scores for memory and calculation (0.06 to 0.013 standard deviations [SD]) and lower scores for nonmemory items (-0.09 to -0.01 SD). Cognition was significantly differentially related to instrumental activities of daily living difficulty depending on assessment mode. Measurement invariance testing identified evidence of mode differences in certain tests as a function of mode: adjusting for underlying cognition, the largest mode differences in memory and attention: immediate noun recall, delayed word recall, and serial-7s scores were higher given telephone administration.

DISCUSSION

Differences by mode of administration are apparent in cognitive measurement in older adults, albeit to a small degree in our study, and most pronounced for tests of memory and attention. The importance of accounting for mode differences ultimately depends on one's research question and study sample: not all associations may be affected by mode differences, and such modification may only be apparent among those with lower cognitive functioning.

Does peak expiratory flow moderate trajectories of cognitive function among individuals with lung diseases? A longitudinal analysis of the National Health and Aging Trends Study

INTRODUCTION

Impaired cognitive function can co-exist in chronic respiratory diseases. However, it is not clear if peak expiratory flow (PEF) impacts changes in cognitive function. Our objective was to explore whether peak expiratory flow moderates trajectories of memory, visuospatial abilities, and executive function in individuals with chronic respiratory diseases.

METHODS

This was an analysis of individuals with lung diseases from the National Health and Aging Trends Study. Multivariable-adjusted generalized linear mixed models were used to estimate trajectories of immediate and delayed recall, and clock drawing over a 10-year follow-up. The interaction between PEF and time were plotted using sex-specific values for peak expiratory flow at 10th, 50th and 90th percentiles.

RESULTS

In females, interactions of time-by-PEF were found for both immediate (n = 489, t = 2.73, p<0.01) and delayed recall (n = 489, t = 3.38, p<0.01). Females in the 10th vs. 90th percentile of PEF declined in immediate recall at 0.14 vs. 0.065 words/year, and 0.17 vs. 0.032 words/year for delayed recall. Among males, recall declined linearly over 10 years (immediate recall: n = 296, t = -3.08, p < 0.01; delayed recall: n = 292, t = -2.46, p = 0.02), with no interaction with PEF. There were no time-by-PEF interactions nor declines over time in clock drawing scores in both sexes (females: n = 484, t = 0.25, p = 0.81; males: n = 291, t = -0.61, p = 0.55).

CONCLUSION

Females with the lowest PEF values experienced the greatest rates of decline in immediate and delayed recall over 10 years of follow-up, whereas males experienced similar declines in memory outcomes across all levels of PEF. Clock drawing scores remained stable over 10 years in both sexes.

Do Sensory Impairments Portend Cognitive Decline in Older Chinese Adults? Longitudinal Evidence from a Nationally Representative Survey, 2011-2018

Previous studies on longitudinal sensory-cognition association are limited and have yielded inconsistent conclusions in western and developed countries. The present study obtained data from the China Health and Retirement Longitudinal Survey (CHARLS, 2011−2018) and aimed to investigate the longitudinal effects of sensory impairments including single vision impairment (SVI), single hearing impairment (SHI), and dual sensory impairment (DSI) on cognitive decline in middle-aged and older Chinese population. In total, 11,122 participants accomplished all 4 interviews over 8 years and were included. Cognitive performances were assessed using Mini-Mental Status Examination (MMSE) and self-reported sensory status were accepted as well. Confounding variables included age, sex, educational level, marital status, medical, and lifestyle related information. The impact of sensory impairment on cognitive decline over time was assessed using linear mixed-effects models (LMM). After being adjusted for multiple confounders, SVI/SHI/DSI were all shown to be significantly associated with executive functions, episodic memory impairment, and global cognitive decline over 8 years (all p < 0.05). Such associations become less significant among female and relatively younger populations (45−59 years old). Single vision and hearing impairments, along with dual sensory impairment, are all independently associated with subsequent cognitive decline among middle-aged and older Chinese populations over 8 years of longitudinal observation.

Bidirectional associations of intellectual and social activities with cognitive function among middle-aged and elderly adults in China

BACKGROUND

Previous studies evaluating the association between leisure activities and cognitive function produced conflicting results. Different types of leisure activities may have different effects on cognition, and very few studies have explored their bidirectional associations. Our study aimed to explore whether intellectual and social activities had bidirectional associations with cognitive function among the middle-aged and elderly adults in China.

METHODS

Data was derived from the China Health and Retirement Longitudinal Study. The data in this study were based on 11,549 participants aged 45 or older whose intellectual and social activities and cognitive function were assessed at baseline. Cross-lagged panel model was used to examine the temporal relationship of intellectual and social activities with cognitive function.

RESULTS

Totally, 5624 participants completed the third follow-up in 2018. The results showed that the better the cognitive function they had at baseline, the more intellectual activities they were engage in (β = 0.044, P < 0.001) and vice versa (β = 0.042, P = 0.001). Additionally, better cognitive function at baseline was significantly associated with more engagement in social activities (β = 0.028, P = 0.030); in contrast, higher engagement in social activities at baseline was not related to better cognitive function (β = -0.008, P = 0.523).

LIMITATIONS

Engagement in social and intellectual activities was assessed via questionnaire.

CONCLUSIONS

Our findings indicated that there was a bidirectional relationship between intellectual activities and cognitive function. However, participation in social activities did not slow down the decline in cognitive function. Participating in intellectual activities, compared to social activities, is especially beneficial for cognitive function.

Examining Racial Disparities in Historical Change of Mental and Physical Health Across Midlife and Old Age in the United States

OBJECTIVES

To examine whether racial disparities are narrowing or widening with historical time among U.S. middle-aged and older adults, and test the extent to which educational attainment moderates racial disparities over historical time.

METHODS

Multilevel models were applied to longitudinal data on middle-aged (ages 40-65) and older adults (ages 66 and older) from the Health and Retirement Study. Historical change was indexed as cohort or birth year. The outcomes of focus were depressive symptoms, episodic memory, health conditions, functional limitations, and self-rated health.

RESULTS

Results revealed a differential pattern of racial disparities in historical change between midlife and old age. Across midlife and old age, on average, Blacks and Hispanics reported poorer levels of mental and physical health, compared with Whites. In midlife, racial disparities narrowed with historical time; later-born cohorts of Hispanics but not Whites reported fewer depressive symptoms than their earlier-born peers. Likewise, historical improvements in health were stronger among Hispanics and Blacks than Whites. Conversely, in old age, later-born cohorts across race consistently showed historical improvements in each of the outcomes examined. Regarding educational attainment, we observed little consistent evidence that health-promoting effects of educational attainment differ across race and cohort. Examining questions about heterogeneity, results revealed that in midlife and old age there was greater heterogeneity between race across each of the outcomes.

DISCUSSION

Our discussion elaborates on reasons behind the documented racial differences in historical changes among U.S. middle-aged and older adults, and how the protective role of education is changing over time.

Associations of physical activity with cognitive function and daily physical function among Chinese individuals with heart disease: A cross-sectional study

Background

To investigate the associations between different dimensions of physical activity (PA), cognitive function, and daily physical function in Chinese individuals with heart disease.

Materials and methods

This study included 2,792 individuals from the China Health and Retirement Longitudinal Study conducted in 2015. Physical activity (PA) was divided into vigorous PA (VPA), moderate PA (MPA), and light PA (LPA). Linear and logistic regression models were established to assess the associations among the indicators.

Results

Compared with taking no PA, MPA, and VPA at a frequency of 6-7 d/w had lower risks of impaired daily physical function (OR = 0.47, 95% CI: 0.25, 0.91; OR = 0.57, 95% CI: 0.37, 0.88) and higher cognitive function scores (β = 1.22, 95% CI: 0.42, 2.03; β = 1.08, 95% CI: 0.43, 1.73), while VPA at 3-5 d/w had lower cognitive function scores (β = -1.96, 95% CI: -3.51, -0.40). Light PA (LPA) with a duration of 30-119 min/d had a lower risk of impaired daily physical function (OR = 0.59, 95% CI: 0.36, 0.97). Moderate PA (MPA) and VPA of 30-119 min/d had higher cognitive function scores (β = 1.43, 95% CI: 0.49, 2.37; β = 1.30, 95% CI: -0.56, 2.06). The 1,800-2,999 METs had the lowest risks of impaired daily physical function and the highest cognitive function scores (OR = 0.18, 95% CI: 0.04, 0.75; β = 2.94, 95% CI: 1.67, 4.21).

Conclusion

Moderate PA (MPA) and LPA with a frequency of 6-7 d/w and a duration of 30-119 min/d, and PA in 1,800-2,999 MET min/week were most closely related to better cognitive and daily physical function, while VPA (3-5 d/w; ≥300 min/w) may be related to low cognition, but high-quality research is necessary to prove causality.

Trial registration

IRB00001052-11015.

Association of walking speed with cognitive function in Chinese older adults: A nationally representative cohort study

BACKGROUND

Slow walking speed has been shown to predict cognitive decline in older individuals, but studies conducted among Chinese older adults are scarce. We examined the association of walking speed with cognitive function and the trajectory of cognitive decline among Chinese adults aged 60 years and older.

METHODS

Data was from the China Health and Retirement Longitudinal Study (CHARLS), an ongoing nationally representative prospective cohort study. Walking speed was evaluated over a straight 2.5-meter flat course at baseline and categorized into tertiles (the lowest, middle, and highest). Cognitive function was assessed at each wave in three domains: episodic memory, mental status, and global cognition. Data were analyzed using linear mixed-effects models.

RESULTS

A total of 3,954 older adults (48.6% female; mean age: 67.6 ± 5.55 years) were followed for up to 7 years. Participants with lowest walking speed have poorer episodic memory (β = -0.37; 95% CI: -0.46, -0.28), mental status (β = -0.45; 95% CI: -0.60, -0.29), and global cognition (β = -0.81; 95% CI: -1.03, -0.60) over the follow-up. Compared with the highest tertile of walking speed, the lowest walking speed was associated with a faster decline in episodic memory (β = -0.04; 95% CI: -0.07, -0.02), mental status (β = -0.04; 95% CI: -0.07, -0.01), and global cognition (β = -0.06; 95% CI: -0.11, -0.01).

CONCLUSION

Slower walking speed is associated with subsequent risk of poorer cognitive function and faster cognitive decline in older Chinese adults.

Socioeconomic Status, Biological Aging, and Memory in a Diverse National Sample of Older US Men and Women

BACKGROUND AND OBJECTIVES

Exposure to socioeconomic disadvantage is associated with early-onset cognitive aging. Biological aging, the progressive loss of system integrity that occurs as we age, is proposed as a modifiable process mediating this health inequality. We examined whether socioeconomic disparities in cognitive aging in mid-to late-life adults is explained by accelerated biological aging similarly across race, ethnicity, and sex/gender.

METHODS

Data were from a prospective cohort study of the US Health and Retirement Study DNA methylation substudy. Socioeconomic status (SES) was measured from years of education and household wealth at baseline. The extent and pace of biological aging were quantified using 3 DNA methylation measures: PhenoAge, GrimAge, and DunedinPoAm. Cognitive aging was measured from repeated longitudinal assessments of immediate and delayed word recall. Latent growth curve modeling estimated participants' level of memory performance and rate of decline over 2-11 follow-up assessments spanning 2-20 years. Multiple-group models were estimated to assess whether the relationship between SES and memory trajectories was mediated by biological aging across racial-ethnic by sex/gender subgroups.

RESULTS

Data from a total of 3,997 adults aged 50-100 years were analyzed. Participants with lower SES had a lower memory performance, had a faster decline, and exhibited accelerated biological aging (SES effect size associations [β] ranged from 0.08 to 0.41). Accelerated biological aging was associated with decreased memory performance and faster memory decline (effect size range 0.03-0.23). SES-biological aging associations were the strongest for White men and women and weakest for Latinx women. The relationship between biological aging measures and memory was weaker for Black participants compared with that for White and Latinx people. In mediation analysis, biological aging accounted for 4%-27% of the SES-memory gradient in White participants. There was little evidence of mediation in Black or Latinx participants.

DISCUSSION

Among a national sample of mid-to late-life adults, DNA methylation measures of biological aging were variably associated with memory trajectories and SES across White, Black, and Latinx mid-to late-life adults. These results challenge the assumption that DNA methylation biomarkers of aging that were developed in primarily White people can equivalently quantify aging processes affecting cognition in Black and Latinx mid-to late-life adults.

Socioeconomic Status, Biological Aging, and Memory in a Diverse National Sample of Older US Men and Women

BACKGROUND AND OBJECTIVES

Exposure to socioeconomic disadvantage is associated with early-onset cognitive aging. Biological aging, the progressive loss of system integrity that occurs as we age, is proposed as a modifiable process mediating this health inequality. We examined whether socioeconomic disparities in cognitive aging in mid-to late-life adults is explained by accelerated biological aging similarly across race, ethnicity, and sex/gender.

METHODS

Data were from a prospective cohort study of the US Health and Retirement Study DNA methylation substudy. Socioeconomic status (SES) was measured from years of education and household wealth at baseline. The extent and pace of biological aging were quantified using 3 DNA methylation measures: PhenoAge, GrimAge, and DunedinPoAm. Cognitive aging was measured from repeated longitudinal assessments of immediate and delayed word recall. Latent growth curve modeling estimated participants' level of memory performance and rate of decline over 2-11 follow-up assessments spanning 2-20 years. Multiple-group models were estimated to assess whether the relationship between SES and memory trajectories was mediated by biological aging across racial-ethnic by sex/gender subgroups.

RESULTS

Data from a total of 3,997 adults aged 50-100 years were analyzed. Participants with lower SES had a lower memory performance, had a faster decline, and exhibited accelerated biological aging (SES effect size associations [β] ranged from 0.08 to 0.41). Accelerated biological aging was associated with decreased memory performance and faster memory decline (effect size range 0.03-0.23). SES-biological aging associations were the strongest for White men and women and weakest for Latinx women. The relationship between biological aging measures and memory was weaker for Black participants compared with that for White and Latinx people. In mediation analysis, biological aging accounted for 4%-27% of the SES-memory gradient in White participants. There was little evidence of mediation in Black or Latinx participants.

DISCUSSION

Among a national sample of mid-to late-life adults, DNA methylation measures of biological aging were variably associated with memory trajectories and SES across White, Black, and Latinx mid-to late-life adults. These results challenge the assumption that DNA methylation biomarkers of aging that were developed in primarily White people can equivalently quantify aging processes affecting cognition in Black and Latinx mid-to late-life adults.

Association of Adverse Childhood Experiences and Social Isolation With Later-Life Cognitive Function Among Adults in China

IMPORTANCE

Studies investigating the association of threat-related and deprivation-related adverse childhood experiences (ACEs) with later-life cognitive decline are lacking.

OBJECTIVES

To evaluate the independent association of threat-related and deprivation-related ACEs with cognitive decline over time among middle-aged and older Chinese adults and to examine the modifying role of social isolation in such associations.

DESIGN, SETTING, AND PARTICIPANTS

This prospective cohort study used cognitive data from the China Health and Retirement Longitudinal Study (CHARLS) baseline survey that was administered between June 1, 2011, and March 31, 2012, and the CHARLS follow-up survey administered between July 1 and September 30, 2015. The life history survey with information of ACEs was additionally administered between June 1 and December 31, 2014. Statistical analysis was performed from March 1 to July 31, 2022. The study population consisted of middle-aged and older adults (age range, 45-97 years) with complete data on ACEs and 2 cognitive assessments and without cognitive impairment at baseline.

EXPOSURES

Five threat-related ACEs (ie, physical abuse, household substance abuse, domestic violence, unsafe neighborhood, and bullying) and 5 deprivation-related ACEs (ie, emotional neglect, household mental illness, incarcerated household member, parental separation or divorce, and parental death) before 17 years of age were queried by questionnaires. The cumulative scores of the 2 ACE dimensions were calculated and grouped into 3 categories as 0, 1, and 2 or more in main analyses.

MAIN OUTCOMES AND MEASURES

Cognitive function was measured by episodic memory and executive function. Global cognition was further calculated as the total score of these 2 dimensions. The raw scores of each cognitive test were standardized to z scores using baseline means and SDs. Linear mixed-effects models were constructed to examine the association between 2 dimensions of ACEs and the rate of annual cognitive decline. The modifying role of baseline social isolation in such associations was assessed with 3-way interaction tests.

RESULTS

Of the 6466 participants included in main analyses, 3301 (51.1%) were men and the mean (SD) age was 57.2 (8.3) years. Compared with no exposures, experience of 1 deprivation-related ACE was associated with faster cognitive decline in global cognition (β = -0.012 [95% CI, -0.022 to -0.002] SD/y) and executive function (β = -0.010 [95% CI, -0.020 to -0.00002] SD/y), whereas individuals with at least 2 childhood deprivations had faster cognitive declines in all cognitive tests (β = -0.035 [95% CI, -0.050 to -0.019] SD/y for global cognition; β = -0.047 [95% CI, -0.068 to -0.025] SD/y for episodic memory; β = -0.019 [95% CI, -0.034 to -0.004] SD/y for executive function). However, such an association was not observed for threat-related ACEs. In addition, baseline social isolation was a significant modifier in the associations between deprivation-related ACEs and cognitive declines in global cognition (β = -0.033 [95% CI, -0.061 to -0.005] SD/y; P = .02 for 3-way interaction) and executive function (β = -0.032 [95% CI, -0.059 to -0.005] SD/y; P = .02 for 3-way interaction).

CONCLUSIONS AND RELEVANCE

Deprivation-related ACEs, but not threat-related ACEs, were associated with faster decline in later-life cognitive function, whereas social isolation could modify such detrimental impact. These findings highlight the potential benefits of promoting social integration in maintaining later-life cognitive function among individuals who have experienced childhood deprivation.

Age Profiles of Cognitive Decline and Dementia in Late Life in the Aging, Demographics, and Memory Study

OBJECTIVES

To better understand the temporal dynamics of progression from cognitive decline to onset of dementia in the dementia-free older population in the United States.

METHODS

We used longitudinal data from a diverse national population-based sample of older adults (N = 531) in the Aging, Demographics, and Memory Study from the Health and Retirement Study with repeated measures of cognitive function and dementia diagnosis during 12 years of follow-up from 1996 to 2009. We employed joint latent class mixed models to estimate the association between cognitive change and competing risks of dementia and nondementia death and identify heterogeneity in the age profiles of such association adjusting for baseline characteristics.

RESULTS

Our analyses found 3 latent classes with distinct age profiles of cognitive decline and associated risk of dementia and mortality: "Rapid Cognitive Decline" (19.6%), "Moderate Progression" (44.6%), and "Optimal Cognitive Aging" (35.8%). When simultaneously accounting for cognitive trajectories and time-to-dementia/death, we also found associations of baseline covariates with slope of cognitive decline (e.g., steeper decline among non-Hispanic Blacks and more educated) and risk of dementia (e.g., greater risk for females and apolipoprotein E-4 carriers, but no difference by education level) that differ substantially from those in separate longitudinal mixed models or survival models.

DISCUSSION

The differential age patterns of cognitive decline predicting dementia incidences identified in this study suggest variation in the course of cognitive aging in older adults that may inform future etiological and intervention studies.

Prospective association between standing balance and cognitive function in middle-aged and older Chinese adults

Objective

To investigate the association of standing balance with cognitive functions and the rate of cognitive decline among middle-aged and older Chinese adults.

Methods

Participants were selected from China’s Health and Retirement Longitudinal Study. A total of 8,499 subjects aged ≥45 years who participated in wave 1 to wave 3 surveys were included in the final analysis. Standing balance was measured using the tandem test, and participants were categorized into two groups according to their ability to maintain standing balance. Cognitive functions were assessed in three domains: episodic memory, mental status, and global cognition. The associations between standing balance scores, cognitive scores, and the rate of cognitive decline were evaluated using linear regression and linear mixed models.

Results

Compared with participants who successfully completed the standing balance test, those who were unable to complete the test had lower scores on episodic memory [β = −0.18; 95% confidence interval (CI): −0.24, −0.11], mental status (β = −0.28; 95% CI: −0.37, −0.19), and global cognition (β = −0.51; 95% CI: −0.65, −0.38) after 4 years of follow-up. In addition, the rate of decline in mental status and global cognition increased by 0.10 (β = 0.10; 95% CI: 0.07, 0.13) and 0.08 (β = 0.08; 95% CI: 0.04, 0.12) units, respectively, in participants who were unable to complete the test compared with their counterparts.

Conclusion

Good standing balance was significantly associated with higher cognitive function and a lower decline in mental status and global cognition in middle-aged and older Chinese adults.

Catastrophic health expenditure among Chinese adults living alone with cognitive impairment: findings from the CHARLS

BACKGROUND

The catastrophic health expenditure of older adults results in serious consequences; however, the issue of whether cognitive status and living situations contribute to such financial burdens is uncertain. Our aim was to compare the differences in catastrophic health expenditure between adults living alone with cognitive impairment and those adults living with others and with normal cognition.

METHODS

We identified 909 observations of participants living alone with cognitive impairment (cases) and 37,432 observations of participants living with others and with normal cognition (comparators) from the 2011/2012, 2013, 2015 and 2018 waves of the China Health and Retirement Longitudinal Study (CHARLS). We used propensity score matching (1:2) to create matched cases and comparators in a covariate-adjusted logistic regression analysis. Catastrophic health expenditure was defined as an out-of-pocket cost for health care ≥40% of a household's capacity to pay.

RESULTS

In comparison with participants living with others and with normal cognition, those adults living alone with cognitive impairment reported a higher percentage of catastrophic health expenditure (19.5% vs. 11.8%, respectively, P < 0.001). When controlling for age, sex, education, marital status, residence areas, alcohol consumption, smoking status and disease counts, we found that this subpopulation had significantly higher odds of having catastrophic health expenditure (odds ratio [OR] = 1.89, 95% confidence interval [CI]: 1.40, 2.56). Additional analyses confirmed the robustness of the results.

CONCLUSIONS

This study demonstrated that adults living alone with cognitive impairment in the CHARLS experienced a high burden of catastrophic health expenditure. Health care policies on social health insurance and medical assistance should consider these vulnerable adults.

Associations between childhood maltreatment and educational, health and economic outcomes among middle-aged Chinese: The moderating role of relative poverty

BACKGROUND

Despite substantial evidence in developed countries showing that child maltreatment can lead to serious life-long consequences, relatively few studies so far have examined the associations between childhood maltreatment and adulthood outcomes in developing countries, such as China. It also remains unclear as to the impact of relative poverty on the long-term development of maltreated children.

OBJECTIVE

This study aims to investigate the associations between childhood maltreatment and educational, health, and economic outcomes among middle-aged Chinese, as well as explore the moderating effects of relative poverty.

PARTICIPANTS AND SETTING

The participants of this study were the middle-aged respondents (aged 45 to 59) in the 2011, 2013, and 2015 China Health and Retirement Longitudinal Studies (CHARLS) and the CHARLS Life History Survey (N = 24,114).

METHODS

Physical abuse and emotional neglect were measured to investigate childhood maltreatment. Subjective and objective indicators were used to examine relative poverty. A broad range of midlife outcomes were explored, including educational attainment, physical health, mental health, cognitive functions, labor force participation, wage expenditure, and financial strain. Data analyses were conducted using fixed effects model for panel data and a propensity score matching approach.

RESULTS

Childhood physical abuse and emotional neglect were both significantly associated with lower levels of midlife educational attainment, cognitive functions, individual wages, and household expenditures, as well as higher rates of chronic diseases, depressive symptoms, poverty, and welfare involvement. Childhood physical abuse also predicted higher risks of difficulty performing the activities of daily living (ADL), unemployment, and fewer work hours. Early-life exposure to relative poverty was linked to a greater likelihood of childhood maltreatment and mid-life adversities. It further aggravated the negative impacts of childhood maltreatment on middle-age outcomes.

CONCLUSION

Child maltreatment had a profound effect on long-term child development and midlife outcomes in Chinese contexts. Relative poverty in early life was a moderator that exacerbated the outcomes associated with childhood maltreatment.

Prevalence and Correlates of Motoric Cognitive Risk Syndrome in Chinese Community-Dwelling Older Adults

Background: Motoric cognitive risk (MCR) syndrome is considered to be a pre-dementia syndrome. Although an increasing number of studies have begun to focus on this syndrome, few investigations have been launched in China. This study was performed to examine the prevalence and correlates of MCR in China.

Methods: We included 5,725 adults aged over 60 years from China Health and Retirement Longitudinal Study (CHARLS). MCR was defined as the presence of subjective cognitive complaints and a gait speed ≤20th percentile of the weighted population distribution adjusted for sex and height. The associations among selected modifiable associated factors and clinical measures with MCR were examined using multivariate logistic regression analysis.

Results: Of the participants, 414 met the criteria for MCR with an overall prevalence 7.29% (95% CI: 6.62–7.96%). MCR was found to be more prevalent among women than men (9.73 vs 4.85%), and more prevalent among participants ≥75 years than those &lt;75 years (7.85 vs 5.23%). After multivariable adjustment, lower or upper extremity functional limitations, activities of daily living (ADL) disabilities, weak grip strength, exhaustion, and history of hypertension were found to be significantly associated with MCR. The multivariate analysis also showed higher levels of cystatin C and C-reactive protein were associated with increased odds for MCR.

Conclusions: The present study showed that MCR syndrome is highly prevalent among Chinese community-dwelling older adults, and revealed several factors that were correlated with MCR. Longitudinal studies are warranted to further explore the modifiable risk factors of MCR.

Depression and memory function - evidence from cross-lagged panel models with unit fixed effects in ELSA and HRS

BACKGROUND

Individuals with depression are often found to perform worse on cognitive tests and to have an increased risk of dementia. The causes and the direction of these associations are however not well understood. We looked at two specific hypotheses, the aetiological risk factor hypothesis and the reverse causality hypothesis.

METHOD

We analysed observational data from two cohorts, English Longitudinal Study of Ageing (ELSA) and Health and Retirement Study (HRS), using cross-lagged panel models with unit fixed effects. Each model was run once with depression and repeated with cognition as the dependent variable and the other variable as the main explanatory variable. All models were estimated separately for contemporaneous effects and lagged effects up to 8 years in the past. We contrasted the results with models making the random effects assumption.

RESULTS

Evidence from the fixed effects models is mixed. We find no evidence for the reverse causality hypothesis in ELSA and HRS. While there is no evidence for the aetiological risk factors hypothesis in ELSA, results from HRS indicate some effects.

CONCLUSION

Our findings suggest that current levels of cognitive function do not influence future levels of depression. Results in HRS provide some evidence that current levels of depressive symptoms influence future cognition.

Green Space, Air Pollution, Weather, and Cognitive Function in Middle and Old Age in China

Prior research has shown that environmental hazards, such as limited green space, air pollution, and harmful weather, have the strong adverse impact on older adults' cognitive function; however, most of the studies were conducted in developed countries and limited to cross-sectional analyses. China has the largest aging population in the world so the research evidence from it can offer an insight to the study in other developing countries facing similar issues and inform future public health policy and disease control. This study examined the long-term impact of environmental factors, namely, green space coverage, air pollution, and weather conditions on cognitive function using a nationally representative sample consisting of adults aged 45 years and older selected from the China Health and Retirement Longitudinal Study (CHARLS 2011–2018), the China City Statistical Yearbook, and other sources. Multilevel growth curve models were utilized for analysis and the mediator effects of physical activity and social engagement on the relationship between environmental factors and cognitive function were examined. Findings of this study showed that after controlling for sociodemographic characteristics, annual precipitation of 80 cm or more, living in areas with July temperature of 28°C or higher, urban community, and green space coverage were positively associated with cognition score at the baseline and lower precipitation, urban community, and greater green space coverage were associated with slower cognitive decline over a 7-year period. The impact of gross domestic product (GDP) seemed to take into effect more and more over time. These effects did not substantially change after weekly total hours of physical activities and levels of social engagement were added. More research on the mechanisms of the effect of environmental factors on cognition is needed such as the subgroup analyses and/or with more aspects of environmental measures.

Longitudinal association between visual disability and cognitive function among middle-aged and older adults in China

BACKGROUND/AIMS

To determine the associations between visual disability and cognitive decline in Chinese middle-aged and older adults.

METHODS

A total of 6748 subjects were enrolled into this longitudinal, population-based, nationally representative study from two waves of the China Health and Retirement Longitudinal Study. Lagged dependent variable regression was used to model the independent associations between self-reported visual disability and cognitive function including memory and mental status.

RESULTS

The mean age of the 6748 individuals was 56.33 years, and 3350 (49.6%) were women. The prevalence of visual disability was 3.8%, which increased with age (p<0.001). Both memory and mental status score worsened over time (all p<0.001). After controlling for covariates, lagged dependent variable regression models showed that visual disability at baseline was significantly associated with memory decline after 7 years (β=-0.252, p=0.046). After stratifying by age groups, this association was only significant in the 55-64 age group (β=-0.372, p=0.033). In addition, both memory and mental status in 2011 predicted memory decline over 7 years (p=0.024 and p=0.045, respectively).

CONCLUSIONS

Our results suggest that visual disability may be a risk factor of memory decline, but not mental status among middle-aged and elderly adults in China. Future studies are needed to further corroborate the association between visual disability and cognitive decline and to determine whether interventions to preserve good visual function can prevent cognitive decline.

Earlier migration, better cognition? The role of urbanization in bridging the urban-rural cognition gaps in middle and older age

OBJECTIVES

With the process of population aging and urbanization, a vast amount of studies have confirmed the increasing urban-rural cognition gaps, while less is known about the extent to which cognition gaps can be explained by urban-rural difference and urbanization status. This study aimed to examine the role of urbanization in bridging the cognition gaps for Chinese middle-aged and older adults.

METHOD

Based on the national representative China Health and Retirement Longitudinal Study (CHARLS) 2015, the Blinder-Oaxaca decomposition method was employed. The method uses stratified linear regression to disaggregate cognition gaps into explained and unexplained differences, as well as the absolute and relative attribution of explanatory factors.

RESULTS

There were significant cognitive differences between urban and rural samples. Migrating to the urban predicts better cognition among the rural-born. A larger environment-related explained gap existed for those fully urbanized and those migrating earlier, indicating that migration can operate through a beneficial and cumulative change in the environment and bridge the urban-rural cognition gap.

CONCLUSION

Public health actions targeting cognitive disparities can benefit from focusing on the unequal distribution in urban-rural social and economic recourses. Areas of priority include promoting their socioeconomic status, physical functioning, social support, and lifestyles.

Race/Ethnic Differences, Skin Tone, and Memory Among Older Latinos in the United States

OBJECTIVES

U.S. Latino populations are diverse. Research on racial identity, skin tone, and Latino health is imperative for understanding and combating racism and colorism. We examined differences in memory performance: among non-Latinos and Latinos who identified as Black, other, and White in the United States and then among Puerto Ricans in Boston whose skin tones ranged from dark, medium, light to "white."

METHODS

We used 2010 Health and Retirement Study and 2004 Boston Puerto Rican Health Survey data, respectively, to examine racial and color differences in memory performance among 50 and older adults in the United States and Puerto Rican older adults in Boston. We applied ordinary least squares regression to immediate and delayed word recall test scores and adjusted for education, health conditions, and health behaviors.

RESULTS

In adjusted models, White non-Latinos had better memory performance than White Latinos. Black Latinos, other Latinos, and Black non-Latinos had lower delayed word recall scores than White Latinos. Black Latinos and Black non-Latinos had similar scores. Intra-Latino racial disparities endured despite the inclusion of education and other covariates. Among Puerto Ricans in Boston, medium-toned individuals had higher scores than "white"-toned individuals.

DISCUSSION

Findings support the importance of examining self-identified race and skin tone in Latino aging research. Further investigation is needed to understand the stubborn intra-Latino racial disparities in memory performance and surprising adverse cognitive performance among "white"-toned relative to darker-toned Puerto Ricans in Boston.

The Effect of Adult Children's Education Attainment on Their Parents' Cognitive Health: An Intergenerational Support Perspective

The purpose of this study is to examine the relationship between adult children's education attainment and their parents' cognitive health, and to further explore the mechanism of intergenerational support. Based on empirical analysis of data from China Health and Retirement Longitudinal Survey, our study finds a positive association between children's educational attainment and parents' cognitive health. This correlation is provided for by emotional communication of informal caregiving, financial support, and healthy behaviors shaped in the parents by adult children. The strength of the effect varied by the adult child's gender. While sons' education attainment significantly improves parental cognitive parameters through informal caregiving, financial support, and development of healthy behaviors, the effect of daughters' education derives from financial support and healthy behaviors, not being related to informal caregiving. The study enriches the evidence on the mobility of children's human capital toward their parents and provides practical insights for advancing children's participation in family caregiving.

Unmet healthcare needs among middle-aged and older adults in China

BACKGROUND

Unmet healthcare needs have increasingly been recognised as an indicator of equity of healthcare access and utilisation, having the potential to capture frailty of health and social protection systems.

OBJECTIVES

This study aimed to estimate the prevalence of unmet healthcare needs and its correlates among middle-aged and older adults in China.

METHODS

This study is based on analyses of the China Health and Retirement Longitudinal Study carried out in 2011 among Chinese adults aged 45 years and above. Multivariable logistic regression models were conducted to examine associated factors, stratified by rural or urban residence. Reasons for having unmet needs for inpatient and outpatient services were also analysed.

RESULTS

Among 14,774 participants, the prevalence of unmet healthcare needs was 13.0% (95% confidence interval 12.3-13.8%) and was higher in rural areas. The most prevalent reasons for unmet need for inpatient and outpatient care were 'not enough money' and 'illness is not serious, don't need treatment', respectively. The respondents who were unmarried, employed, had poor self-reported health, needed help with activities of daily living, reported lower life satisfaction, multiple chronic conditions and depressive symptoms had increased odds of unmet healthcare needs.

CONCLUSION

This study suggests that unmet healthcare needs are more concentrated among people living with multiple health conditions and mental health problems in China. If universal health coverage goals and sustainable development goal 3 are to be met, it is essential that effective mechanisms for addressing unmet healthcare needs are identified.

Change in Episodic Memory With Spousal Loss: The Role of Social Relationships

OBJECTIVES

The spousal relationship is one of the most important social contexts in old age, and the loss of a spouse/partner is associated with stress and cognitive decline. In the present study, we examined whether social relationships can buffer potential negative effects of spousal loss on cognition. We examined the role of social network, social activities, and perceived deficiencies in social relationships (loneliness).

METHOD

We used longitudinal data between 1998 and 2012 from 2,074 participants of the Health and Retirement Study, who had experienced spousal loss during the study period. Multilevel modeling was used to examine how time-varying indicators of social network, social activities, and loneliness were related to age-related trajectories of episodic memory prior to and after spousal loss. Analyses controlled for gender, race/ethnicity, education, time-varying functional health, and being repartnered/remarried.

RESULTS

Having children living within 10 miles and providing help to others buffered negative effects of widowhood on episodic memory. In addition, within-person increase in providing help to others buffered against decline in episodic memory after spousal loss. Having friends in the neighborhood, more frequent social visits, providing help to others, volunteering, and lack of loneliness were related to higher episodic memory, while having relatives in the neighborhood was related to lower episodic memory.

DISCUSSION

Our findings suggest that social networks, social activities, and loneliness are related to levels of cognitive function at the time of spousal loss and that social relationships can buffer negative effects of spousal loss on cognitive function. Implications for future research are discussed.

Intersectional Discrimination Attributions and Health Outcomes Among American Older Adults: A Latent Class Analysis

Guided by an intersectionality framework, this study examined intersectional discrimination attributions and their associations with health outcomes. Older respondents (aged ≥50) from the Health and Retirement Study in 2014-2015 were included (N = 6286). Their reasons for discrimination (age, gender, sexual orientation, race, national origin, religion, financial status, weight, physical appearance, disability, and others) were examined. Latent class analysis examined the subgroup profiles. Six classes were identified: class 1 (54.52% of the sample) had no/minimal discrimination; Class 2 (21.89%) experienced primarily ageism; class 3 (8.81%) reported discrimination based on age/gender/national origin/race; class 4 (7.99%) attributed discrimination to financial/other reasons; class 5 (5.87%) experienced discrimination based on age/weight/physical appearance/disability; and class 6 (0.92%) perceived high discrimination. Intersectional discrimination was associated with poorer self-rated health and higher depressive symptoms compared to the no/minimal discrimination group. Multiple marginalized identities co-occur and contribute to discrimination. An intersectional approach is recommended to understand discrimination in later life.

Social isolation, rather than loneliness, is associated with cognitive decline in older adults: the China Health and Retirement Longitudinal Study

BACKGROUND

Social isolation and loneliness have each been associated with cognitive decline, but most previous research is limited to Western populations. This study examined the relationships of social isolation and loneliness on cognitive function among Chinese older adults.

METHODS

This study used two waves of data (2011 and 2015) from the China Health and Retirement Longitudinal Study (CHARLS) and analyses were restricted to those respondents aged 50 and older. Social isolation, loneliness, and cognitive function were measured at baseline. Follow-up measures on cognitive function were obtained for 7761 participants (mean age = 60.97, s.d. = 7.31; male, 50.8%). Lagged dependent variable models adjusted for confounding factors were used to evaluate the association between baseline isolation, loneliness, and cognitive function at follow-up.

RESULTS

Loneliness was significantly associated with the cognitive decline at follow-up (episodic memory: β = -0.03, p < 0.01; mental status: β = -0.03, p < 0.01) in the partially adjusted models. These associations became insignificant after additional confounding variables (chronic diseases, health behaviors, disabilities, and depressive symptoms) were taken into account (all p > 0.05). By contrast, social isolation was significantly associated with decreases in all cognitive function measures at follow-up (episodic memory: β = -0.05, p < 0.001; mental status: β = -0.03, p < 0.01) even after controlling for loneliness and all confounding variables.

CONCLUSIONS

Social isolation is associated with cognitive decline in Chinese older adults, and the relationships are independent of loneliness. These findings expand our knowledge about the links between social relationships and the cognitive function in non-Western populations.