A Prospective Study on the Association Between Grip Strength and Cognitive Function Among Middle-Aged and Elderly Chinese Participants

Association between physical fitness and executive functions in cognitively healthy female older adults: a cross-sectional study

Cardiovascular endurance and muscular fitness seem to impact specific cognitive components in older females. However, it remains uncertain whether these relate to executive functions or if these correlations are limited to specific physical fitness indicators. This study aimed to determine the association between specific physical fitness components and executive functions in community-dwelling older females. Thirty-five cognitively healthy community-dwelling older females (71.5 ± 5.7 years) underwent a series of physical fitness tests. These included the handgrip strength test (HGT), the 6-min walk test (6MWT), the 8-foot up-and-go test (8FUGT), and the chair stand test (CST). Participants also completed trail A and trail B of the cognitive trail making test. Results showed that trail B reaction time had a negative association with both HGT (r =  - 0.502; p = 0.002) and 6MWT (r =  - 0.543; p < 0.001). Together, the HGT and 6MWT results explained 39% of the variation in trail B reaction times: HGT accounted for 18% and 6MWT for 21%. Better scores on the 6MWT and HGT-but not on the 8FUGT and CST-correlated with enhanced executive function in cognitively healthy community-dwelling older females. The results of this study underscore the importance of specific physical assessments, like the 6MWT and HGT, as potential indicators of executive function, offering targeted strategies for maintaining cognitive health in aging females.

Digital Exclusion and Cognitive Function in Elderly Populations in Developing Countries: Insights Derived From 2 Longitudinal Cohort Studies

BACKGROUND

Cognition disorders not only lead to adverse health consequences but also contribute to a range of socioeconomic challenges and diminished capacity for performing routine daily activities. In the digital era, understanding the impact of digital exclusion on cognitive function is crucial, especially in developing countries.

OBJECTIVE

This study aimed to evaluate the association between digital exclusion and cognitive function among elderly populations in developing countries.

METHODS

Using data from CHARLS (China Health and Retirement Longitudinal Study) from 2011 to 2020 and MHAS (Mexican Health & Aging Study) from 2012 to 2021, we defined digital exclusion as self-reported absence from the internet. Cognitive function was assessed through 5 tests: orientation, immediate verbal recall, delayed verbal recall, serial 7s, and figure recall. Cognitive function was assessed in 2 categories: worse cognition (a categorical variable that classifies cognition as either better or worse compared to the entire cohort population) and cognitive scores (a continuous variable representing raw cognitive scores across multiple follow-up waves). Logistic regression analyses and generalized estimating equation (GEE) analyses were used to examine the relationship between cognitive function and digital exclusion, adjusting for potential confounders, including demographics, lifestyle factors, history of chronic diseases, basic activities of daily living (BADL) disability, instrumental activities of daily living (IADL) disability, and basic cognitive abilities.

RESULTS

After excluding participants with probable cognitive impairment at baseline and those who did not have a complete cognitive assessment in any given year (ie, all tests in the cognitive assessment must be completed in any follow-up wave), a total of 24,065 participants in CHARLS (n=11,505, 47.81%) and MHAS (n=12,560, 52.19%) were included. Of these, 96.78% (n=11,135) participants in CHARLS and 70.02% (n=8795) in MHAS experienced digital exclusion. Adjusted logistic regression analyses revealed that individuals with digital exclusion were more likely to exhibit worse cognitive performance in both CHARLS (odds ratio [OR] 2.04, 95% CI 1.42-2.99; P<.001) and MHAS (OR 1.40, 95% CI 1.26-1.55; P<.001). Gender and age did not significantly modify the relationship between digital exclusion and worse cognition (intervention P>.05). The fully adjusted mean differences in global cognitive scores between the 2 groups were 0.98 (95% CI 0.70-1.28; P<.001) in CHARLS and 0.50 (95% CI 0.40-0.59; P<.001) in MHAS.

CONCLUSIONS

A substantial proportion of older adults, particularly in China, remain excluded from internet access. Our study examined longitudinal changes in cognitive scores and performed cross-sectional comparisons using Z-score standardization. The findings suggest that digital exclusion is linked to an increased risk of cognitive decline among older adults in developing countries. Promoting internet access may help mitigate this risk and support better cognitive health in these populations.

Handgrip strength: A simple and effective tool to recognize decreased intrinsic capacity in Chinese older adults

OBJECTIVES

Intrinsic capacity impairment results in poor outcomes among older adults. Here we tested handgrip strength as a screening tool for IC impairment in community-dwelling older adults in Xinjiang, China. We assessed the diagnostic accuracy and established optimal cut-off points for handgrip strength in the detection of intrinsic capacity impairment.

METHODS

In total, 1072 participants were included using a multilevel random sampling method. Intrinsic capacity was constructed according to the definition of the Integrated Care for Older People screening tool proposed by the WHO.

RESULTS

Altogether, 73.4 % (787/1072) participants had intrinsic capacity impairment. The prevalence of intrinsic capacity impairment for hearing, vision, mobility, cognition, psychological, and vitality domains was 8.6 %, 4.8 %, 39.6 %, 47.3 %, 12.0 %, and 18.8 %, respectively. The adjusted odds ratios [95 % confidence interval) for handgrip strength was 0.935 [0.914-0.956]. The area under the curve of the receiver operating characteristic curve for handgrip strength of older men, and handgrip strength of older women with intrinsic capacity impairment were 0.7278, and 0.7534, respectively. The handgrip strength cut-off points were 28.47 kg (60-69 years), 25.76 kg (70-79 years), and 24.45 kg (≥80 years) for men, and 20.75 kg (60-69 years), 19.90 kg (70-79 years), and 16.17 kg (≥80 years) for women.

CONCLUSIONS

Handgrip strength can be used as a convenient tool for evaluating intrinsic capacity. Weak handgrip strength and low education level were associated with intrinsic capacity impairment in community-dwelling older adults in Xinjiang. Using the cut-off points of handgrip strength for different age groups and genders, older adults with impaired intrinsic capacity can be identified, which may reduce the occurrence of adverse outcomes.

The Grip Strength Loss Rate and the Subsequent Cognitive Decline Rate in Older Adults: The Moderating Role of Social Isolation

Background and Objectives

Accumulating evidence suggests that low grip strength (GS) is associated with a faster cognitive decline, but most previous studies have measured GS at a single time point, ignoring changes in GS. We aimed to explore the association of the GS loss rate with the sequent cognitive decline, as well as the moderating role of social isolation in older adults.

Research Design and Methods

Data were from the English Longitudinal Study of Ageing. Absolute and relative GS loss rates were calculated as the annual losses from Wave 2 (2004-05) to Wave 4 (2008-09). Participants were divided into 3 groups according to the tertiles of GS loss rates. Linear mixed models were used to assess the association of the GS loss rate during Waves 2-4 with the cognitive decline rate during Waves 4-9 (Wave 9, 2018-19).

Results

Of the 4 356 participants included in analyses, 1 938 (44.5%) were men, with a mean age of 68.4 (SD: 8.4) years. Compared with Tertile 1 of the absolute GS loss rate, Tertile 2 (β = -0.009 [95% CI: -0.018 to -0.001] SD/year) and Tertile 3 (β = -0.018 [95% CI: -0.027 to -0.010] SD/year) were associated with a faster cognitive decline rate. The results of relative GS were similar to those of absolute GS. Social isolation was a significant modifier in the associations of the absolute GS loss rate with decline rates in global cognition and episodic memory, but not in temporal orientation. We did not observe that social isolation moderated the association of the relative GS loss rate with the cognitive decline rate.

Discussion and Implications

Both absolute and relative GS loss rates were positively associated with the cognitive decline rate in older adults. Low social isolation scores attenuated the association of the absolute GS loss rate with the cognitive decline rate.

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.

Arterial stiffness and physical fitness on cognitive function in community-dwelling middle-aged and older adults

PURPOSE

This study examined whether decline in cognitive function is related to arterial stiffness and reduction in physical fitness in middle-aged and older adults.

METHODS

A total of 1554 healthy middle-aged and older adults participated in this study. The trail making test parts-A (TMT-A) and B (TMT-B), brachial-ankle pulse wave velocity (baPWV), grip strength, the 30-s chair stand (CS-30) test, the 6-min walk (6MW) test, the 8-foot up-and-go (8UG) test and gait assessment were performed. Participants were classified into a middle-aged group (40-64 years; mean, 50.4 ± 0.2 years) or an older group (≥ 65 years; mean, 73.1 ± 0.5 years), as well as into three cognition (COG) groups (high, moderate, and low) based on median TMT-A and -B scores (high scores on both, either, or neither TMT-A and -B, respectively).

RESULTS

The results revealed that baPWV was significantly lower in the high-than in the moderate- and low-COG groups in both middle-aged and older adults (P < 0.05). In addition, except for a few parameters (e.g., 6MW test in middle-aged adults), physical fitness was significantly higher in the high-than in the moderate- and low-COG groups in both middle-aged and older adults (P < 0.05). Multivariate regression analysis revealed that baPWV (P < 0.05) and some physical fitness indicators (grip strength, CS-30, and 8UG) were significantly independently associated with both TMT-A and -B in the middle-aged and older groups (P < 0.05).

CONCLUSION

These results suggest that increased arterial stiffness and reduced physical fitness are associated with impaired cognitive function in middle-aged and older adults.

Impacts of combined childhood exposures to poor neighborhood quality, peer friendships and family relationships on adult depression: A seven-year longitudinal study

BACKGROUND

Little is known about how multisystemic childhood exposures predict adult depression. This study aims to examine the effects of multisystemic childhood exposures on the onset and remission of adult depression.

METHODS

Data were drawn from the China Health and Retirement Longitudinal Survey (CHARLS) (wave 1-4), which is a nationally representative longitudinal survey of people 45 years of age or older in China. Childhood family relationships (CFR), childhood peer friendships (CPF), and childhood neighborhood quality (CNQ) scores were recoded into binary (No = 0, Yes = 1) according to the first quantile value. Participants were divided into four groups based on the total number of poor childhood exposures (group 0-3). The generalized linear mixed model was used to test the longitudinal relationship between combined poor childhood exposures and adult depression.

RESULTS

Of the 4696 participants (55.1 % males), 22.5 % suffered from depression at baseline. The incidence of depression increased from group0 to group3 in four waves, reaching the peak in wave 2018 (incidence of group0 to group3: 14.1 %, 18.5 %, 22.8 %, 27.4 %, p < 0.001), with declining remission rates that reached its lowest in wave 2018 (50.8 %, 41.3 %, 34.3 %, 31.7 %, p < 0.001). The persistent depression rate increased from group0 to group3 (2.7 %, 5.0 %, 8.1 %, 13.0 %, p < 0.001). The risk of depression in group1 (AOR = 1.50, 95%CI: 1.27-1.77), group2 (AOR = 2.43, 95%CI: 2.01-2.94) and group3 (AOR = 4.24, 95%CI: 3.25-5.54) were significantly higher than that in group0.

LIMITATIONS

Childhood histories were collected via self-reported questionnaires, and thus recall bias was inevitable.

CONCLUSIONS

Multisystem poor childhood exposures jointly increased the onset and persistence of adult depression, as well as reduced the remission rate of depression.

Handgrip strength is associated with risks of new-onset stroke and heart disease: results from 3 prospective cohorts

BACKGROUND

Stroke and heart disease are two major contributors to the global disease burden. We aimed to evaluate and compare the roles of different handgrip strength (HGS) expressions in predicting stroke and heart disease in three nationally representative cohorts.

METHODS

This longitudinal study used data from the Health and Retirement Study (HRS), the Survey of Health, Ageing, and Retirement in Europe (SHARE), and the China Health and Retirement Longitudinal Study (CHARLS). The Cox proportional hazard model was applied to analyze the relationship between HGS and stroke and heart disease, and Harrell's C index was used to assess the predictive abilities of different HGS expressions.

RESULTS

A total of 4,407 participants suffered from stroke and 9,509 from heart disease during follow-up. Compared with the highest quartile, participants in the lowest quartile of dominant HGS, absolute HGS and relative HGS possessed a significantly higher risk of new-onset stroke in Europe, America, and China (all P < 0.05). After adding HGS to office-based risk factors, there were minimal or no differences in the increases of Harrell's C indexes among three HGS expressions. In contrast, the modest association between HGS and heart disease was only seen in SHARE and HRS, but not in CHARLS.

CONCLUSION

Our findings support that HGS can be used as an independent predictor of stroke in middle-aged and older European, American and Chinese populations, and the predictive ability of HGS may not depend on how it is expressed. The relationship between HGS and heart disease calls for further validation.

High-Sensitivity C-Reactive Protein, Its Change, and Cognitive Function: A National Population-Based Cohort Study

This study aimed to evaluate the associations of baseline high-sensitivity C-reactive protein (Hs-CRP) and its change with subsequent cognitive decline and cognitive impairment. Data for this study were obtained from the China Health and Retirement Longitudinal Study, a national community-based prospective cohort study. Hs-CRP level and cognitive function were measured repeatedly over a 7-year follow-up. Linear mixed models and cox proportional hazard models were used to evaluate the associations. The study comprised 7385 participants (50.67% women, mean age 59.08 ± 8.86 years) with baseline Hs-CRP ranging from 0.03 to 178.10 mg/L (median: 1.01 mg/L, IQR: 0.55-2.11 mg/L). During a median of 5.79 years follow-up, the highest quartile of the Hs-CRP group showed a faster rate of cognitive decline (-0.0053 SD/year, p = 0.006) and a higher risk of cognitive impairment (HR 1.0814, p = 0.044) than those in the lowest quartile. Individuals in the elevated group of Hs-CRP change had a significantly faster cognitive decline (-0.0070 SD/year, p = 0.016) compared with those in the stable group. In this study, significant longitudinal associations between baseline Hs-CRP, elevated Hs-CRP, and long-term cognitive deterioration were observed. Hs-CRP level could perhaps serve as a predictor for cognitive deterioration in middle-aged and older adults.

Associations of Pain and Sarcopenia with Successful Aging among Older People in China: Evidence from CHARLS

OBJECTIVES

Sarcopenia and chronic pain are geriatric syndromes that negatively impact the lives of older people. The aim of this study was to explore the relationship among sarcopenia, pain, and successful aging among older persons participating in the China Health and Retirement Longitudinal Study (CHARLS).

DESIGN

Cohort study with a 2-year follow-up.

SETTING AND PARTICIPANTS

Data were derived from 2 waves of the CHARLS, and 4280 community-dwelling participants aged ≥ 60 years were included in the study.

METHODS

Sarcopenia status was defined according to the Asian Working Group for Sarcopenia 2019 (AWGS 2019) criteria. Successful aging was defined following Rowe and Kahn's multidimensional model. Pain was assessed by a self-reported questionnaire. A generalized estimating equation (GEE) was used to examine the associations.

RESULTS

Longitudinal results demonstrated that compared with no sarcopenia, possible sarcopenia [OR (95%CI): 0.600 (0.304~1.188)] was not significantly associated with successful aging. Pain only was strongly associated with successful aging [0.388 (0.251~0.600)], whereas the association between sarcopenia only and successful aging was weaker [0.509 (0.287~0.905)]. The likelihood of being successful aging was substantially lower in the presence of coexisting sarcopenia and pain [0.268 (0.108~0.759)].

CONCLUSIONS

Both pain and sarcopenia are significant predictors for achieving successful aging among community-dwelling older adults. Early identification of sarcopenia and pain permits the implementation of treatment strategies and presents an opportunity to mitigate the risk of being unsuccessful aging.

Urbanization and Cognitive Function Among Middle-Aged and Old Adults in China

OBJECTIVES

Our study examined the effect of urbanization on cognitive function and its possible pathways among Chinese middle-aged and older adults independent of the influence of health-selective migration.

METHODS

Using data from the China Health and Retirement Longitudinal Study, we compared cognitive function among three groups (urbanized-rural residents, rural nonmigrants, and urban nonmigrants). Logistic regression and structural equation models were applied to explore the impact of urbanization on cognitive function and the potential mechanisms.

RESULTS

Compared with the urbanized-rural group, urban nonmigrants had better cognitive function, with a significant coefficient of 1.56 (95% CI: 1.22, 1.89) for global cognition scores and 0.37 (95% CI: 0.22, 0.53) for episodic memory scores. The rural nonmigrants had the worst cognitive function (β = -0.79, 95% CI: -1.04, -0.55) and lower scores of mental intactness (β = -0.65, 95% CI: -0.84, -0.57) and episodic memory (β = -0.14, 95% CI: -0.26, -0.03). The association between urbanization and cognitive function was mainly mediated by income and living conditions among middle-aged and older adults.

DISCUSSION

Rural people who experienced planned urbanization in China had higher cognitive scores than rural non-migrants. Urbanization could thus have a beneficial and cumulative effect on cognitive function. Improvements in living conditions and changes in income are the main drivers behind the relationship. However, urbanization could compensate for the negative impact on cognitive function from disadvantaged early-life conditions, but it cannot completely eliminate the gap between urbanized-rural people and urban nonmigrants.

Association between grip strength and cognitive impairment in older American adults

BACKGROUND AND AIMS

Exponential population aging has led to an increased prevalence of cognitive impairment worldwide. Hand grip strength, which may be associated with physical activity, could be a useful predictor of cognitive impairment. However, few studies have reported the association, if any, between hand grip strength and cognitive function.

METHODS

We used data obtained from the National Health and Nutrition Examination Survey between 2011-2012 and 2013-2014 to investigate the association between hand grip strength and cognitive impairment. Cognitive impairment was assessed using the Consortium to Establish a Registry for Alzheimer's Disease (CERAD), animal fluency (AF), and digit symbol substitution test (DSST) scores. Cutoff values of CERAD < 5, AF < 14, and DSST < 34 were used to define cognitive impairment. In this cross-sectional study, we used odds ratios to determine the potential usefulness of hand grip strength for the prediction of cognitive impairment.

RESULTS

This study included 2,623 participants aged ≥60 years. The DSST results showed that hand grip strength was associated with a low risk of cognitive impairment and that subgroup analysis showed that male sex, 60-69 years of age, and the Non-Hispanic (NH)-White, NH Black, and Asian were associated with a significantly low risk of cognitive impairment. The CERAD test results showed that 70-79 years of age and the NH White were significantly associated with a low risk of cognitive impairment. By following full adjustment, we did not observe statistically significant differences between hand grip strength and cognitive impairment based on the CERAD test. The AF test results showed that >80 years of age, female sex, and the NH White were associated with a significantly low risk of cognitive impairment. The most important finding is that a linear association lies between grip strength and cognitive impairment, as well as a sex-based linear association. Machine learning of the XGBoost model suggests that grip strength is one of the top two most important negative predictor variables.

CONCLUSION

We observed an inverse relationship between hand grip strength and cognitive impairment, which might suggest a shared underlying mechanism that needs to be further investigated using a large-scale prospective clinical trial to validate our findings.

Associations of low handgrip strength and hand laterality with cognitive function and functional mobility - the Yishun Study

Background

Emerging evidence suggest that in addition to low hand grip strength (HGS), HGS asymmetry is associated with declining cognitive and physical functions. We examined the associations of low HGS and asymmetry with cognitive function and functional mobility in older adults.

Methods

Cross-sectional data of 330 community-dwelling adults (55.2% women) aged ≥ 55 years included HGS, Repeated Battery for the Assessment of Neuropsychological Status (RBANS), and Timed-Up-and-Go (TUG). Low HGS was defined as < 28 kg for men and < 18 kg for women. Participants with HGS above 10% stronger on either hand were considered as having HGS asymmetry. Multiple linear regression models were adjusted for sociodemographic, smoking, education, comorbidity count, physical activity participation, obesity, self-rated health and hand dominance.

Results

Low HGS, but not asymmetry, was independently associated with lower functional mobility performance (β = 1.3, 95%CI = 0.6,1.9), global cognitive function (β = -10.4, 95%CI = -17.0,-3.8), immediate (β = -2.6, 95%CI = -4.5,-0.7) and delayed (β = -2.8, 95%CI = -5.0,-0.7) memory. Compared to normal and symmetric HGS participants, low HGS in combination with HGS asymmetry was associated with poorer language scores. In participants with normal HGS, asymmetric HGS was associated with slower TUG than corresponding groups with symmetric HGS.

Conclusion

Low HGS, but not asymmetry, was associated with lower cognition and functional mobility. Associations of combined low HGS and asymmetry with cognitive and physical functions were driven by grip strength rather than asymmetry.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12877-022-03363-2.

Association Between Grip Strength and Cognitive Function in US Older Adults of NHANES 2011–2014

Background: The relationship between grip strength and cognitive function remains no consensus in the older adults. Objective: To investigate the association of grip strength with cognitive function and cognitive performance in different domains. Methods: Participants of the present cross-sectional study were from the National Health and Nutrition Examination Survey 2011-2014. Grip strength was measured by grip dynamometer, and combined handgrip strength was the sum of the largest reading from each hand. Four cognitive domains (immediate and delayed memory, language, and attention) were assessed by a set of neuropsychological tests. The subjective cognitive decline was determined via self-report. Results: Among 2,618 participants, combined grip strength was positively associated with scores on global cognitive function and each cognitive domain after controlling for demographic characteristics, lifestyle factors, and history of disease. In addition, compared to those with grip strength <  46.7 kg, participants with grip strength≥75.3 kg had odds ratios of 0.36 (95% CI: 0.21 to 0.63) for poor global cognitive function, 0.66 (95% CI: 0.38 to 1.13) for poor immediate memory, 0.53 (95% CI: 0.30 to 0.93) for poor delayed memory, 0.48 (95% CI: 0.27 to 0.86) for poor language function, 0.20 (95% CI: 0.11 to 0.35) for poor attention, and 0.36 (95% CI: 0.18 to 0.73) for subjective cognitive decline in fully adjusted model. Conclusion: Older adults with higher grip strength were significantly associated with better performance on cognition function included global and various domains such as memory, language, attention, and subjective cognitive decline.

Increased cortisol levels caused by acute resistance physical exercise impair memory and learning ability

Acute physical exercise works as an activator of the responses of the human organism to stress. This is based on the activation of the hypothalamic-pituitary-adrenal (HPA) axis, affecting physical, physiological and psychological levels. This study aimed to analyse the effects of a single bout of high-intensity resistance exercise on cognitive-behavioural responses: visuo-spatial path learning and memory, as well as physiological responses (salivary cortisol levels). Nineteen healthy male military-trained powerlifting subjects were tested in a within-subject design on two experimental days with an interval of 48 h. The stress and cognitive variables were measured by cortisol levels and Ruff-Light trail-learning test (RULIT) test scores, respectively. The results showed the immediate influence of acute exercise on cortisol, with significantly higher cortisol levels found in subjects after completion of the acute resistance exercise. In addition, this study found a significant deterioration of memory and learning ability after a dose of intense resistance exercise. In conclusion, the study highlights the relative effects of resistance exercise on cortisol and cognitive performance depending on the intensity and type of the exercise, the moment of measurement and the cerebral areas implicated.

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.

Association between Handgrip Strength and Cognitive Function in Older Adults: Korean Longitudinal Study of Aging (2006-2018)

Accumulating research indicates that handgrip strength is associated with cognitive function. Studies have also shown the difference in cognitive decline between males and females. We investigated the association between baseline handgrip strength and later cognitive function in older adults according to sex using the dataset from Korean Longitudinal Study of Aging (2006–2018). Overall, 9707 observations of 1750 participants (989 males and 761 females) over 65 years of age were sampled from the first wave, followed by six consecutive waves. The Korean version of the Mini-Mental State Examination and baseline handgrip strength scores were assessed. Sociodemographic and health-related variables were also included as covariates in the multivariable linear mixed models. Males in the lowest quartile of the baseline handgrip strength decreased in cognitive function (β = −0.54, standard error (SE) = 0.16, p < 0.001), compared to males in the highest quartile. For females, those in the second lowest quartile (β = −0.65, SE = 0.19, p < 0.001) and the lowest quartile (β = −0.53, SE = 0.19, p< 0.01) decreased in cognitive function. Handgrip strength may be positively associated with later cognitive function, but the association may be non-linear and differ between sexes. Sex-specific preventive assessment of handgrip strength may help identify older adults at risk for cognitive impairment.

Interaction of declined handgrip strength and HIV infection on neurocognitive impairment

Neurocognitive impairment (NCI) persists among people living with HIV (PLWH) despite the success of combination antiretroviral therapy (cART). Although muscular waning or decreased handgrip strength has been widely reported to be associated with cognitive erosion in general elders, such association has not been examined in PLWH who commonly experience decreased handgrip strength and NCI. Furthermore, whether HIV infection modifies such association remains to be addressed. A cross-sectional analysis was conducted with 2808 HIV-positive and 5402 HIV-negative adults participating in the baseline survey of the CHART (Comparative HIV and Aging Research in Taizhou) cohort, China, 2017 - 2019. HIV-positive individuals showed weaker handgrip strength than HIV-negative controls (34.0 kg vs 37.7 kg). Multivariate logistic regression analysis indicated that both HIV infection (aOR = 4.35, p < 0.001) and every 5-kg decrease in "Handgrip strength" (aOR = 1.27, p < 0.001) were significantly associated with NCI, and there was a significant interaction between reduced handgrip strength and HIV infection on NCI (aOR = 1.14, p = 0.015). In stratified analyses adjusting for potential confounders, the association between reduced handgrip strength and NCI was significant among PLWH at all age groups but only significant among HIV-negative controls at 30 - 44 and 60 - 89 ages. Handgrip strength decline is significantly associated with the risk of NCI among PLWH. HIV infection may exacerbate the adverse effect of poor handgrip strength on NCI, especially at younger ages. Early detection of handgrip strength decline could facilitate delivery of compensatory strategies or assistive services to PLWH with or at high risk of NCI.

Predicting cognitive function based on physical performance: findings from the China Health and Retirement Longitudinal Study

BACKGROUND

Physical performance tests are simple means of predicting an individual's risk of cognitive decline.

AIMS

This study aimed to assess the predictive value of physical performance tests and develop predictive models for cognitive function.

METHODS

Cognitive function was tested biennially and calculated for mental intactness, episodic memory, and global cognition. Using a generalized estimating equation (GEE), we examined each baseline physical performance test as a predictor of cognitive decline. Using a multivariate linear regression model (MLRM), we developed predictive models for cognitive function. Bland-Altman analysis was performed to analyze the agreement between estimated and measured cognition. We validated the predictive model internally with 1000 bootstrap resamples.

RESULTS

Better physical performance test results, except for standing balance, were associated with a slower cognitive decline over time and better cognitive function at follow-up. Regarding the predictive models, all physical performance tests were included in men; only five chair stands test was included in women. Bland-Altman analysis showed that measured cognition was equivalent to estimated cognition in men (mean bias, 0; 95% limits of agreement, - 8.56 to 8.56) and women (mean bias, 0; 95% limits of agreement - 8.79 to 8.7). Bootstrap analysis showed that predictors were selected in 78.4-100% for men and 64.5-100% for women.

DISCUSSION

Bland-Altman and bootstrap analysis demonstrated good agreement and stability of the predictive models.

CONCLUSIONS

Physical performance tests are simple, easily obtainable, and clinically relevant markers for cognitive function with aging; predictive models based on physical performance can be used to predict cognitive function.

Socioeconomic differences in handgrip strength and its association with measures of intrinsic capacity among older adults in six middle-income countries

Handgrip strength, a measure of muscular strength is a powerful predictor of declines in intrinsic capacity, functional abilities, the onset of morbidity and mortality among older adults. This study documents socioeconomic (SES) differences in handgrip strength among older adults aged 50 years and over in six middle-income countries and investigates the association of handgrip strength with measures of intrinsic capacity-a composite of all the physical and mental capacities of an individual. Secondary data analysis of cross-sectional population-based data from six countries from the WHO's Study on global AGEing and adult health (SAGE) Wave 1 were conducted. Three-level linear hierarchical models examine the association of demographic, socioeconomic status and multimorbidity variables with handgrip strength. Regression-based Relative Index of Inequality (RII) examines socioeconomic inequalities in handgrip strength; and multilevel linear and logistic hierarchical regression models document the association between handgrip strength and five domains of intrinsic capacity: locomotion, psychological, cognitive capacity, vitality and sensory. Wealth quintiles are positively associated with handgrip strength among men across all countries except South Africa while the differences by education were notable for China and India. Work and nutritional status are positively associated with handgrip strength. Our findings provide new evidence of robust association between handgrip strength and other measures of intrinsic capacity and confirms that handgrip strength is a single most important measure of capacity among older persons.

Association between handgrip strength and cognition in a Chinese population with Alzheimer's disease and mild cognitive impairment

Background

This study aimed to explore the level and changes in handgrip strength among preclinical Alzheimer’s disease (AD) and AD patients and to evaluate the association between handgrip strength and cognitive function.

Methods

A total of 1431 participants from the memory clinic of Shanghai JiaoTong University Affiliated Sixth People’s Hospital and community were enrolled in the final analysis, including 596 AD, 288 mild cognitive impairment (MCI), and 547 normal individuals (NC). All participants received a comprehensive neuropsychological assessment. Mini-Mental State Examination (MMSE), Montreal Cognitive Assessment-Basic (MoCA-BC), and the Chinese version of Addenbrooke’s Cognitive Examination III (ACE-III-CV) were used as cognitive tests. The receiver operating characteristic curve (ROC) was plotted to assess the power of handgrip strength as a screening measure to discriminate AD and MCI.

Results

The results showed that handgrip strength in the MCI group was significantly lower than that of NC group, and the AD group had a further decline (both P < 0.01). Multivariate logistic regression was performed with the handgrip strength quartiles, and the results showed that the ORs of AD for increasing levels of handgrip strength were 1.00, 0.58 (0.46–0.78), 0.51 (0.36–0.73), and 0.50 (0.35–0.68), showing a decreasing trend (P_{for trend} < 0.01). The ROC curve demonstrated that the handgrip strength cutoff points for the identification of AD were 16.8 and 20.7 kg among the female participants above and under 70 yrs and 24.4 and 33.3 kg for the male participants above and under 70 yrs, respectively. Similarly, for the identification of MCI, cutoff points were 17.5 and 21.9 kg for females above 70 yrs and under 70 yrs, and 25.8 and 36.2 kg for males above 70 yrs and under 70 yrs, respectively.

Conclusions

Our study provided the further knowledge on the relationship between noncognitive features and cognition in populations with differing cognitive status, revealed that the stronger handgrip strength was associated with better performances on cognitive function. It can be speculated that handgrip strength can help early recognition of Chinese AD patients.

Association Between Muscle Strength and Cystatin C-Based Estimated Glomerular Filtration Rate Among Middle-Aged and Elderly Population: Findings Based on the China Health and Retirement Longitudinal Study (CHARLS), 2015

Background

Patients with chronic kidney disease (CKD) are prone to muscle strength degeneration. However, the relationship between mild-to-moderate renal insufficiency and low muscle strength remains unclear. As cystatin C is not subject to muscular conditions and is a sensitive serum marker in preclinical renal disease, we aimed to investigate the association between estimated glomerular filtration rate (eGFR) based on cystatin C and muscle strength in the Chinese population.

Methods

This was a cross-sectional study enrolling 12,398 Chinese participants aged above 45 years (5762 men and 6636 women) from the 2015 China Health and Retirement Longitudinal Study. Handgrip strength (HGS) was used to assess muscle strength. Locally weighted scatterplot smoothing (LOWESS) curves were employed to visualize the relationships between eGFR and HGS. Multivariable logistic regression was conducted to analyze the correlation between kidney function and low muscle strength.

Results

Significant differences in HGS by CKD stage were observed in both sexes after adjusting for age and body mass index. LOWESS curves demonstrated concomitant decreases in HGS and kidney function at eGFR levels below 120 mL/min/1.73 m² in both sexes. According to multivariate logistic regression, participants with CKD stages 2 (odds ratio [OR]: 1.256, 95% confidence interval [CI]: 1.120–1.409), 3 (OR: 2.725, 95% CI: 2.2585–3.288), and 4–5 (OR: 3.069, 95% CI 1.747–5.392) had higher risk of low muscle strength than those who were normal or had CKD stage 1 after adjusting for demographic and clinical variables.

Conclusion

Our study illustrated that CKD stage was independently associated with low muscle strength in Chinese middle-aged and elderly populations.

Effects of the association between APOE rs405509 polymorphisms and gene-environment interactions on hand grip strength among middle-aged and elderly people in a rural population in southern China

Background

Hand grip strength is a complex phenotype. The current study aimed to identify the effects of the association between APOE rs405509 polymorphisms and gene-environment interactions on hand grip strength among middle-aged and elderly people in a rural population in Gongcheng, southern China.

Methods

APOE rs405509 polymorphisms in 1724 participants (695 men and 1029 women, aged 45–97 years old) were genotyped using the Sequenom MassARRAY platform. Statistical analysis was conducted using SPSS 21.0 and Plink 1.90.

Results

The APOE rs405509 G allele was associated with lower hand grip strength in all participants (β = −1.04, P value <0.001), and the correlation seemed to be even stronger among women. A significant gene-environment interaction was observed between APOE rs405509 and smoking, especially in men. The hand grip strength of male smokers carrying the GG genotype was significantly higher than that of nonsmokers (P value = 0.004).

Conclusions

APOE rs405509 polymorphisms might be genetic factors that affect hand grip strength in a rural population in Gongcheng, southern China. The APOE rs405509-smoking interaction has an impact on hand grip strength.

The handgrip strength and risk of depressive symptoms: a meta-analysis of prospective cohort studies

PURPOSE

Many studies have investigated the association between handgrip strength (HGS) and depressive symptoms, but the conclusion remain controversial. We performed a meta-analysis to evaluate the longitudinal association between HGS and risk of depressive symptoms.

METHODS

PubMed, PSYCINFO and EMBASE databases were searched for eligible publications up to April 2020. Pooled relative risks (RRs) with 95% confidence intervals were calculated using random-effects model. Publication bias was estimated using Egger's test and the funnel plot. Newcastle-Ottawa Scale (NOS) was used to evaluate the quality of eligible studies.

RESULTS

The present meta-analysis included 8 cohort studies with 30,727 participants. Overall, higher HGS was related to a decreased risk of depressive symptoms: the pooled risk ratio (RR) of 0.74 [95% confidence intervals (CI) 0.65-0.85] with a moderate heterogeneity (I² = 60.5%, P = 0.013). HGS was significantly associated with a reduced risk of depressive symptoms in males (RR = 0.69; 95% CI 0.50-0.94), but not in females.

CONCLUSIONS

Lower HGS was associated with an increased risk of depressive symptoms. Further studies are needed to confirm these findings and to investigate the sex differences.

Development and Validation of a Nomogram Based on Motoric Cognitive Risk Syndrome for Cognitive Impairment

Objective

To develop and validate a prediction nomogram based on motoric cognitive risk syndrome for cognitive impairment in healthy older adults.

Methods

Using two longitudinal cohorts of participants (aged ≥ 60 years) with 4-year follow-up, we developed (n = 1,177) and validated (n = 2,076) a prediction nomogram. LASSO (least absolute shrinkage and selection operator) regression model and multivariable Cox regression analysis were used for variable selection and for developing the prediction model, respectively. The performance of the nomogram was assessed with respect to its calibration, discrimination, and clinical usefulness.

Results

The individualized prediction nomogram was assessed based on the following: motoric cognitive risk syndrome, education, gender, baseline cognition, and age. The model showed good discrimination [Harrell’s concordance index (C-index) of 0.814; 95% confidence interval, 0.782–0.835] and good calibration. Comparable results were also seen in the validation cohort, which includes good discrimination (C-index, 0.772; 95% confidence interval, 0.776–0.818) and good calibration. Decision curve analysis demonstrated that the prediction nomogram was clinically useful.

Conclusion

This prediction nomogram provides a practical tool with all necessary predictors, which are accessible to practitioners. It can be used to estimate the risk of cognitive impairment in healthy older adults.

Effects of physical activity on cognitive function among patients with diabetes in China: a nationally longitudinal study

Background

We aimed to examine the effect of physical activity on different cognitive domains among patients with diabetes.

Methods

We used two waves of data from the Chinese Health and Retirement Longitudinal Study (CHARLS, 2013–2015), a nationally representative dataset of Chinese population aged over 45. Total physical activity scores were calculated based on the International Physical Activity Questionnaire (IPAQ). Executive function and episodic memory were used as measures of cognitive function. We conducted lagged dependent variable models to explore the association between physical activity and cognitive function in full sample as well as two different age groups (45–65, ≥65). Results: 862 diabetic patients were included. We found that diabetic participants who had greater level of physical activity at baseline were associated with better episodic memory function in 2 years (p < 0.05). Moreover, physical activity was significantly associated with less decline in episodic memory in fully adjusted models, and the associations were stronger among patients aged 45–65 years (p < 0.05). No statistically significant association was found between physical activity and executive function in all age groups.

Conclusions

Physical activity may prevent some of the potential decline in episodic memory in diabetic patients. Clinicians and public health departments should strengthen the promotion of physical activity and develop early screening tools among diabetic participants to prevent the progression of cognitive impairment.

Challenging the relationship of grip strength with cognitive status in older adults

OBJECTIVE

Grip strength is a widely used motor assessment in ageing research and has repeatedly been shown to be associated with cognition. It has been proposed that grip strength could enhance cognitive screening in experimental or clinical research, but this study uses multiple data-driven approaches to caution against this interpretation. Furthermore, we introduce an alternative motor assessment, comparable to grip dynamometry, but has a more robust relationship with cognition among older adults.

DESIGN

Associations between grip strength and cognition (measured with the Montreal Cognitive Assessment) were analysed cross sectionally using multivariate regression in two datasets: (1) The Irish LongituDinal Study on Ageing (TILDA; N = 5,980, community-dwelling adults ages 49-80) and (2) an experimental dataset (N = 250, community-dwelling adults aged 39-98). Additional statistical simulations on TILDA tested how ceiling effects or skewness in these variables influenced these associations for quality control.

RESULTS

Grip strength was significantly but weakly associated with cognition, consistent with previous studies. Simulations revealed this was not due to skewness/ceiling effects. Conversely, a new alternative motor assessment (functional reaching [FR]) had a stronger, more robust and more sensitive relationship with cognition compared to grip strength.

CONCLUSIONS

Grip strength should be cautiously interpreted as being associated with cognition. However, FR may have a stronger and clinically useful relationship with cognition.

The association between health-related factors, physical and mental diseases, social activities, and cognitive function in elderly Koreans: a population-based cross-sectional study

AIM

The purpose of this study was to verify the association of cognitive function with health-related variables, diseases, and social activities.

METHODS

Data from the 2016 Korean Longitudinal Study of Aging were analyzed. The participants of that study were 5678 adults aged 60 years or older living in 17 major Korean regions nationwide.

RESULTS

Hierarchical multiple regression analyses indicated that gender, age, education, marital status, depressive symptoms, body mass index, regular exercise, activities of daily living, instrumental activities of daily living, hand grip strength, and social activities were all significantly associated with cognitive function in elderly Koreans. However, socioeconomic status, diabetes, smoking, alcohol consumption, attendance at school reunions, volunteer work, and participation in political or civic organizations had no impact on cognitive function. First, the results indicated that men had better cognitive function than women; likewise, married individuals and those with a higher level of education also had better cognitive function. As age increased, cognitive function declined. Second, higher body mass index was related to poorer cognitive function, whereas regular exercise was positively associated with better cognitive function. In addition, higher activities of daily living and instrumental activities of daily living scores were associated with poorer cognitive function. Third, depressive symptoms were negatively associated with cognitive function. Finally, religious activities, social activities, and participation in leisure activities, cultural events, and sports were associated with better cognitive functioning. The possibility of reverse association exists between some of the variables (e.g. religious activity and cognitive function), and it is necessary to verify this possibility through a longitudinal study. The biggest limitation is that this is a cross-sectional study, which made it unfeasible to investigate the causal pathways.

CONCLUSIONS

This study suggests that regularly exercising and attending social activities each help to improve cognitive function in the elderly.

The Importance of Exercise in Alzheimer's Disease and the Minds in Motion® Program: An Editorial

Alzheimer's Disease (AD) and other dementias are prevalent neurodegenerative diseases characterized by decreased cognition, physical function, and quality of life. Currently, millions of people are living with AD and other dementias. With no cure, research has examined the use of non-pharmacological treatment options including exercise. Many high-quality studies demonstrate that physical activity slows the progression of AD's many outcomes, and is beneficial to overall quality of life in those living with AD. However, creating exercise interventions at the community level that individuals will adhere to is often a challenge. The Alzheimer's Society of Canada developed a unique program that combines physical activity with cognitive stimulation in a social atmosphere: The Minds in Motion® program. Minds in Motion® addresses many of the barriers often linked to poor physical activity participation in chronic diseases (such as inclusion of the care partner), to ensure the best program uptake. The Minds in Motion® program has anecdotally been successful in helping to increase physical function and social skills in those living with dementia. However, it is important to connect community-driven programs with the academic research community, to create an opportunity for high quality evaluation metrics that can be disseminated at multiple levels: to research audiences, clinical audiences, and to those in the community. With ongoing collaborations between research and community programs, there is a greater opportunity to understand the positive impact of a program, which ultimately increases the chance of funding for the program. In this editorial, we highlight that community-integrated research is an important priority for future collaborations.