Exploring the reciprocal relationship between cognitive function and edentulism among middle-aged and older adults in China

Relationship between triglyceride-glucose index and cognitive function among community-dwelling older adults: a population-based cohort study

Background

The global increase in the aging population presents considerable challenges, particularly regarding cognitive impairment, a major concern for public health. This study investigates the association between the triglyceride-glucose (TyG) index, a measure of insulin resistance, and the risk of cognitive impairment in the elderly.

Methods

This prospective cohort study enrolled 2,959 participants aged 65 and above from the 2015 and 2020 waves of the China Health and Retirement Longitudinal Study (CHARLS). The analysis employed a logistic regression model to assess the correlation between the TyG index and cognitive impairment.

Results

The study included 2,959 participants, with a mean age of 71.2 ± 5.4 years, 49.8% of whom were female. The follow-up in 2020 showed a decrease in average cognitive function scores from 8.63 ± 4.61 in 2015 to 6.86 ± 5.45. After adjusting for confounding factors, a significant association was observed between TyG index quartiles and cognitive impairment. Participants in the highest quartile (Q4) of baseline TyG had a higher risk of cognitive impairment compared to those in the lowest quartile (Q1) (odds ratio [OR]: 1.97, 95% confidence intervals [CI]: 1.28-2.62, P<0.001).

Conclusion

The study highlights a significant connection between elevated TyG index levels and cognitive impairment among older adults in China. These findings suggest that targeted interventions to reduce the TyG index could mitigate cognitive impairment and potentially lower the incidence of dementia.

The relationship between handgrip strength and cognitive function among older adults in China: Functional limitation plays a mediating role

BACKGROUND

The deterioration of cognitive function with age has become a major public health issue. To date, the underlying mechanisms of the association between handgrip strength and cognitive function were poorly understood. This study aimed to examine the mediating effect of functional limitation in the longitudinal relationship between handgrip strength and subsequent cognitive function.

METHODS

This research recruited 4416 participants aged 60 and above from wave 2015 and 2018 of the China Longitudinal Study of Health and Retirement (CHARLS). We conducted the linear regression model and bootstrap analyses to test the mediating role of functional limitation in the relationship between handgrip strength and cognitive function.

RESULTS

After adjusting the confounders, handgrip strength was positively associated with subsequent cognitive function (β = 0.12, P < 0.001) and was negatively associated with functional limitation (β = -0.14, P < 0.001). The mediation effect of functional limitation accounted for 23.33 % of the total effect regarding the handgrip strength with cognitive function, and the magnitude of mediation effect was a*b = 0.021 (95%CI: 0.017-0.027).

LIMITATIONS

The variable of functional limitations was self-reported. And this study did not analyse the severity and duration of handgrip strength loss and functional limitations, which may lose some information.

CONCLUSIONS

Our findings revealed that handgrip strength not only directly influenced cognitive function among older individuals but also indirectly via functional limitation over 3-year follow-up. Physical exercise targeting handgrip strength and functional limitation may be an effective approach to prevent and delay cognitive decline.

Association of edentulism and all-cause mortality in Chinese older adults: do sex differences exist?

OBJECTIVES

Previous studies revealed that tooth loss or edentulism was related to mortality. However, research in developing countries with large numbers of elderly populations is rare, and whether sex differences exist in this relationship is unknown. This study aimed to investigate the association between edentulism and 7-year all-cause mortality among older adults in China and whether sex differences existed.

STUDY DESIGN

This was a prospective cohort study.

METHODS

Data were from 2011 to 2018 waves of the China Health and Retirement Longitudinal Study. A total of 6538 participants aged ≥60 years were included. Logistic models were adopted to estimate the risks of mortality according to edentulism.

RESULTS

The participants with edentulism at baseline were 20% more likely to die over 7 years after controlling for a set of covariates (odds ratio [OR] = 1.20, 95% confidence interval [CI]: 1.02-1.42). Moreover, edentulism was associated with a 35% higher odds of death among male participants (OR = 1.35, 95% CI: 1.08-1.70), whereas a significant association was not found in female participants.

CONCLUSIONS

The findings demonstrated that baseline edentulism predicted all-cause mortality in Chinese older adults, and sex differences existed in this association. This study implied the importance of developing oral health education programs, incorporating dietary recommendations into dental care for edentulous patients, and expanding the coverage of dental services in the health insurance system to prevent edentulism and alleviate its negative outcomes for older adults.

Exploring the reciprocal relationship between activities of daily living disability and depressive symptoms among middle-aged and older Chinese people: a four-wave, cross-lagged model

BACKGROUND

Early studies have shown a relationship between activities of daily living (ADL) disability and depressive symptoms in older people. However, discussions on the direction of this relationship are insufficient. The study's objective was to assess the reciprocal relationship between ADL disability and depressive symptoms among middle-aged and older Chinese people.

METHOD

Data was collected in four waves of a nationwide survey, the China Health and Retirement Longitudinal Study (CHARLS), which was carried out in 2011, 2013, 2015, and 2018. In total, this study included 4,124 participants aged ≥ 45 years at baseline. A summing score of the eleven items for basic activities of daily living (BADL) and instrumental activities of daily living (IADL) was calculated to indicate the degree of ADL disability. The 10-item Centre for Epidemiological Studies Depression Scale (CESD-10) was adopted to measure depressive symptoms. The reciprocal relationship between ADL disability and depressive symptoms was tested by cross-lagged models.

RESULT

At baseline, 911 (22.1%) participants were classified as having difficulties with ADL, and the prevalence of depressive symptoms was 34.4% (1,418). Among middle-aged and older people in China, there was a significant reciprocal and longitudinal relationship between ADL disability and depressive symptoms. People who had difficulty with ADL faced a higher risk of depressive symptoms, and those who suffered from depressive symptoms were accompanied by an increase in ADL disability in the following years. The subgroup analysis on age also showed that ADL disability was reciprocally and longitudinally related to depressive symptoms. However, only women showed similar results in the subgroup analysis on gender.

CONCLUSION

This study shows that ADL disability is bi-directionally related to depressive symptoms in middle-aged and older Chinese people over time. The results suggest we should identify ADL disability and bad psychological conditions in time to prevent subsequent mutual damage among middle-aged and older Chinese people, a vulnerable group rising in the future.

Longitudinal association of edentulism with cognitive impairment, sarcopenia and all-cause mortality among older Chinese adults

BACKGROUND

Tooth loss may be a surrogate for systemic health and aging. However, no previous studies have systematically assessed multiple outcomes relevant to aging trajectory in this area, and many important confounders were not adjusted in most previous studies. This study aims to prospectively evaluate the associations of complete tooth loss (edentulism) with broad markers of sarcopenia, cognitive impairment and mortality.

METHODS

Data were derived from the China Health and Retirement Longitudinal Study, a nationally representative household study of the Chinese population aged 45 years and older. Multivariate Weibull proportional hazards regression was used to assess the association between edentulism with sarcopenia and all-cause mortality. Average changes in cognitive function by edentulism was estimated by mixed-effects linear regression models.

RESULTS

During the 5-year follow-up, the prevalence of edentulism among adults aged 45 and over was 15.4%. Participants with edentulism had a greater decline in cognitive function compared to those without (β=-0.70, 95%CI:-1.09, -0.31, P < 0.001). The association of edentulism and all-cause mortality for 45-64 age group (HR = 7.50, 95%CI: 1.99, 28.23, P = 0.003), but not statistically significant for the ≥ 65 age group (HR = 2.37, 95%CI: 0.97, 5.80, P = 0.057). Effects of edentulism on sarcopenia are statistically significant for all age groups (45-64 age group: HR = 2.15, 95%CI: 1.27, 3.66, P = 0.005; ≥65 age group: HR = 2.15, 95%CI: 1.27, 3.66, P = 0.002).

CONCLUSIONS

These findings could have important clinical and public health implications, as tooth loss is a quick and reproducible measurement that could be used in clinical practice for identifying persons at risk of accelerated aging and shortened longevity, and who may benefit most from intervention if causality is established.

Tooth loss, body mass index and cognitive function among middle-aged and older adults in China: Does gender matter?

BACKGROUND

Previous studies have shown a longitudinal association between tooth loss and cognitive function. Body mass index (BMI) is an essential applicable indicator of health status screening. However, the underlying mechanism among these factors remains unclear. This study aimed to determine the mediating role of BMI in the tooth loss-cognition relationship by gender among Chinese middle-aged and older adults.

METHODS

This is a prospective and cohort study. We used three waves of follow-up data (2011, 2013, and 2015) from the China Health and Retirement Longitudinal Survey, including 10,013 participants aged 45 years or above. Cognitive function was evaluated by Telephone Interview of Cognitive Status, words recall, and figure drawing. The cross-lagged panel model was applied to test the hypothesized model.

RESULTS

Tooth loss is associated with higher BMI and lower level of cognitive function. We found significant total effects (B = -0.017, P = 0.008), direct effect (B = -0.015, P = 0.022) and indirect effects (B = -0.002, P = 0.010) of tooth loss on cognition mediated through BMI only among middle-aged and older men. For middle-aged and older women, the total effect (B = -0.010, P = 0.125) and direct effect (B = -0.007, P = 0.249) were no more significant.

CONCLUSIONS

The longitudinal association between tooth loss and cognition was primarily indirect through BMI among middle-aged Chinese males but not women. Public health authorities should remind middle-aged and older males with tooth loss and high BMI to participate in timely medical checkups for improving cognition.

The Bidirectional Association Between Cognitive Function and Gait Speed in Chinese Older Adults: Longitudinal Observational Study

BACKGROUND

Cognitive and gait speed decline are common conditions in older adults and are often associated with future adverse consequences. Although an association between cognitive function and gait speed has been demonstrated, its temporal sequence remains unclear, especially in older Chinese adults. Clarifying this could help identify interventions to improve public health in older adults.

OBJECTIVE

This study aims to examine the longitudinal reciprocal association between gait speed and cognitive function and the possible temporal sequence of changes in both factors in a national longitudinal cohort.

METHODS

Data were derived from 2 waves (2011 baseline and 2015 follow-up) of the China Health and Retirement Longitudinal Study (CHARLS). Participants 60 years or older, without dementia or Parkinson disease at baseline, and with completed data on gait speed and cognition at both baseline and follow-up were included. Usual gait speed was measured over two 2.5-m walks. Mental intactness and episodic memory were used to assess global cognitive function. Cross-lagged panel models and linear mixed-effects models were used to examine the association between cognition and gait speed over time. Standardized coefficients were reported.

RESULTS

A total of 3009 participants (mean age 66.4 years, SD 5.4 years; 1422/3009, 47.26%, female participants) were eligible for inclusion in our analyses. Cross-lagged panel analyses revealed that after accounting for baseline gait speed, cognition, and potential confounders, baseline global cognition (β=.117, 95% CI 0.082-0.152; P<.001), mental intactness (β=.082, 95% CI 0.047-0.118; P<.001), and episodic memory (β=.102, 95% CI 0.067-0.137; P<.001) were associated with subsequent gait speed. Simultaneously, baseline gait speed was also associated with subsequent global cognition (β=.056, 95% CI 0.024-0.087; P=.001), mental intactness (β=.039, 95% CI 0.008-0.069; P=.01), and episodic memory (β=.057, 95% CI 0.023-0.092; P=.001). The comparison of standardized cross-lagged coefficients suggested that the effect size of baseline global cognition on subsequent gait speed was significantly larger than the reverse effect (χ₁²=6.50, P for difference=.01). However, the effects of both mental intactness and episodic memory on subsequent gait speed were not significantly stronger than those of the reverse pathway (χ₁²=3.33, P for difference=.07 and χ₁²=3.21, P for difference=.07). Linear mixed-effects analyses further supported these bidirectional relationships, revealing that lower baseline cognitive scores predicted steeper declines in gait speed trajectory, and slower baseline gait speed predicted more declines in cognitive trajectory over time.

CONCLUSIONS

There is a longitudinal bidirectional association between usual gait speed and both global cognitive function and specific domains of mental intactness and episodic memory among Chinese older adults. Baseline global cognition is likely to have a stronger association with subsequent gait speed than the reverse pathway. This interlinkage is noteworthy and may have implications for public health. Maintaining normal cognitive function may be an important interventional strategy for mitigating age-related gait speed reduction.

Relationship between Cognition, Depression, and Oral health status in Older adults: A longitudinal cross-lagged analysis

BACKGROUND

The world's population is aging increasingly, and older adults' physical and mental health needs to be prioritized. Although several studies have explored the relationship between cognition, depression, and oral health in older adults, the exact nature and direction of this relationship are poorly understood. Moreover, most studies to date have been cross-sectional, with fewer longitudinal studies. The current longitudinal study explored the relationship between cognition, depression, and oral health in older adults.

METHODS

We used data from two waves (2018, 2020) of the Korean Longitudinal Study of Aging, which included 4543 older adults aged 60 years and older. General socio-demographic characteristics were analyzed using descriptive analysis, and study variables were described using t-tests. Generalized Estimating Equations (GEE) and cross-lagged models were used to examine the longitudinal associations between cognition, depression, and oral health.

RESULTS

The GEE results suggested that better cognition and less depression over time were associated with better oral health in older adults. Cross-lagged models further validated the effect of depression on oral health over time.

LIMITATIONS

The directionality of the influence of cognition on oral health could not be determined.

CONCLUSIONS

Although there were several limitations, our study provided novel ideas for verifying the effects of cognition and depression on oral health in older adults.

Unhealthy oral status contributes to the older patients with cognitive frailty: an analysis based on a 5-year database

BACKGROUND

Oral health is associated with the onset and deterioration of cognitive function and physical frailty, which can be improved with appropriate interventions. However, far too little attention has been paid to oral health status of elderly with cognitive frailty. The objective of this study was to investigate the oral health status and potential risk factors of elderly hospitalized patients aged 60 years or older with cognitive frailty.

METHODS

The participants' assessment data derived from the Comprehensive Geriatric Assessment Database of hospitalized patients from The First Affiliated Hospital of Chongqing Medical University. Data were collected from April 2016 to December 2021. All participants underwent a face-to-face assessment conducted by professional evaluators. Physical frailty was defined by Fried's criteria. Cognitive function was assessed by Mini Mental State Examination (MMSE). The cognitive frailty is characterized by the simultaneous presence of at least 1 Fried's criteria and mild cognitive impairment according to Diagnostic and Statistical Manual of Mental Disorders 5th edition. The oral health was assessed according to 10-item Brief Oral Health Status Examination (BOHSE). The general demographic characteristics, BOHSE scores were compared between the cognitive frailty and non-cognitive frailty (control group). The score of BOHSE and ten items were included in the binary logistic regression analysis. The covariate characteristics were adjusted for a final model with a multivariate analysis.

RESULTS

A total of 425 patients (245 females) with cognitive frailty and 491 patients (283 females) with non-cognitive frailty were enrolled in this retrospective study. Univariate analysis showed statistically significant differences in age, education level, living arrangement, diabetes, Body Mass Index (BMI), Pittsburgh Sleep Quality Index (PSQI), depression between the two groups. The total BOHSE score of cognitive frailty was higher than that of the control group (4.35 ± 2.68 vs. 3.64 ± 2.60, Z = 4.07, P < 0.001). The average scores and the proportions of health changes and unhealthy states of tongue, mucosa tissue, gums, natural teeth, dentures, masticatory teeth and oral hygiene in cognitive frailty were greater than those of the control group (all P < 0.05). The binary logistical regression analysis showed that four or more natural teeth decayed or broken was independently associated with cognitive frailty after adjusting the age, gender, education level, living arrangement and BMI, PSQI, diabetes and depression (OR = 1.91, 95%CI: 1.20-3.07, P = 0.007). Additionally, while in the chewing position, those cases with a normal-occlusal-relationship number of less than 11 pairs had a higher risk of cognitive frailty than those with 12 pairs or more.

CONCLUSIONS

The oral health status of older hospitalized patients over 60 years with cognitive frailty was worse than that of patients with non-cognitive frailty. But only four or more natural teeth decayed or broken and a reduction in chewing pairs were independent risk factors for cognitive frailty.

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.

Translation, cross-cultural adaptation, and validation of the Chinese version of self-efficacy and attitudes for providing Mouth Care scale

Background

In recent years, oral care for older people has received extensive attention in long-term care facilities. The Self-Efficacy for Providing Mouth Care (SE-PMC) and Attitudes for Providing Mouth Care (A-PMC) scale evaluated the self-efficacy and attitude of nursing staff while providing oral care. However, whether this scale is valid and reliable for Chinese nursing staff in China remains unverified. This study aims to translate the English version of SE-PMC and A-PMC into Chinese and determine their reliability and validity.

Methods

After obtaining the author’s consent, the procedure for a double-back translation and cross-cultural adaptation was conducted to develop the Chinese version of SE-PMC and A-PMC. The validity and reliability of the Chinese version of SE-PMC and A-PMC were evaluated in a cross-sectional observational study with 852 nurses from 42 Geriatric Care Facilities (GCFs). Exploratory factor analysis (EFA) (n = 427) and confirmatory factor analysis (CFA) (n = 425) were conducted to test the construct validity and quality of the factor structures. We applied the item discrimination test and homogeneity test for item analysis. Cronbach’s alpha coefficient and split-half coefficient were adopted to evaluate internal consistency.

Results

The Chinese version of SE-PMC (11 items, 3 factors) and A-PMC (11 items, 2 factors) included 22 items, reflecting adequate construct validity and reliability. In addition, test-retest reliability was 0.809 for SE-PMC and 0.811 for A-PMC, evincing good stability. The Cronbach’s α coefficient of SE-PMC was 0.831, with each factor ranging from 0.793~0.906. The Cronbach’s α coefficient of the A-PMC was 0.768, with each factor ranging from 0.814~0.824. Item-Content Validity Index (I-CVI) of SE-PMC and A-PMC ranged from 0.84 ~1.00 and 0.82~1.00, respectively.

Conclusion

The Chinese version of SE-PMC and A-PMC was validated as a reliable assessment tool to evaluate the self-efficacy and attitude of nursing staff in GCFs for providing oral care in China.

Effects of the Co-occurrence of Diabetes Mellitus and Tooth Loss on Cognitive Function

OBJECTIVE

Both diabetes mellitus (DM) and poor oral health are common chronic conditions and risk factors of Alzheimer's disease and related dementia among older adults. This study assessed the effects of DM and complete tooth loss (TL) on cognitive function, accounting for their interactions.

METHODS

Longitudinal data were obtained from the 2006, 2012, and 2018 waves of the Health and Retirement Study. This cohort study included 7,805 respondents aged 65 years or older with 18,331 person-year observations. DM and complete TL were self-reported. Cognitive function was measured by the Telephone Interview for Cognitive Status. Random-effect regressions were used to test the associations, overall and stratified by sex.

RESULTS

Compared with older adults without neither DM nor complete TL, those with both conditions (b = -1.35, 95% confidence interval [CI]: -1.68, -1.02), with complete TL alone (b = -0.67, 95% CI: -0.88, -0.45), or with DM alone (b = -0.40, 95% CI: -0.59, -0.22), had lower cognitive scores. The impact of having both conditions was significantly greater than that of having DM alone (p < .001) or complete TL alone (p = 0.001). Sex-stratified analyses showed the effects were similar in males and females, except having DM alone was not significant in males.

CONCLUSION

The co-occurrence of DM and complete TL poses an additive risk for cognition. Healthcare and family-care providers should pay attention to the cognitive health of patients with both DM and complete TL. Continued efforts are needed to improve older adults' access to dental care, especially for individuals with DM.