A Narrative Review of Handgrip Strength and Cognitive Functioning: Bringing a New Characteristic to Muscle Memory

Hindlimb immobilization induces insulin resistance and elevates mitochondrial ROS production in the hippocampus of female rats

Alzheimer's disease (AD) is the fifth leading cause of death in older adults, and treatment options are severely lacking. Recent findings demonstrate a strong relationship between skeletal muscle and cognitive function, with evidence supporting that muscle quality and cognitive function are positively correlated in older adults. Conversely, decreased muscle function is associated with a threefold increased risk of cognitive decline. Based on these observations, the purpose of this study was to investigate the negative effects of muscle disuse [via a model of hindlimb immobilization (HLI)] on hippocampal insulin sensitivity and mitochondrial function and identify the potential mechanisms involved. HLI for 10 days in 4-mo-old female Wistar rats resulted in the following novel findings: 1) hippocampal insulin resistance and deficits in whole body glucose homeostasis, 2) dramatically increased mitochondrial reactive oxygen species (ROS) production in the hippocampus, 3) elevated markers for amyloidogenic cleavage of amyloid precursor protein (APP) and tau protein in the hippocampus, 4) and reduced brain-derived neurotrophic factor (BDNF) expression. These findings were associated with global changes in iron homeostasis, with muscle disuse producing muscle iron accumulation in association with decreased serum and whole brain iron levels. We report the novel finding that muscle disuse alters brain iron homeostasis and reveal a strong negative correlation between muscle and brain iron content. Overall, HLI-induced muscle disuse has robust negative effects on hippocampal insulin sensitivity and ROS production in association with altered brain iron homeostasis. This work provides potential novel mechanisms that may help explain how loss of muscle function contributes to cognitive decline and AD risk.NEW & NOTEWORTHY Muscle disuse via hindlimb immobilization increased oxidative stress and insulin resistance in the hippocampus. These findings were in association with muscle iron overload in connection with iron dysregulation in the brain. Overall, our work identifies muscle disuse as a contributor to hippocampal dysfunction, potentially through an iron-based muscle-brain axis, highlighting iron dysregulation as a potential novel mechanism in the relationship between muscle health, cognitive function, and Alzheimer's disease risk.

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.

Hand Grip Force-Time Curve Indicators Evaluated by Dynamometer: A Systematic Review

BACKGROUND

Handgrip strength (HGS) is an indicator of muscular strength, used in the diagnosis of sarcopenia, undernutrition, and physical frailty as well as recovery. Typically, the maximum HGS value is used; however, recent evidence suggests the exploration of new indicators provided based on the force-time curve to achieve a more comprehensive assessment of muscle function. Therefore, the objective was to identify indicators of the HGS profile beyond maximum HGS, based on force-time curves, and to systematize knowledge about their applications to various types of samples, health issues, and physical performance.

METHODS

A systematic review was performed including studies whose participants' HGS was assessed with a digital or adapted dynamometer. The outcome measures were HGS profile indicators calculated from the force-time curve.

RESULTS

a total of 15 studies were included, and the following indicators were identified: grip fatigue, fatigability index, fatigue rate, fatigue resistance, time to 80% maximal voluntary contraction, plateau coefficient of variability, time to maximum value, T-90%, release rate, power factor, grip work, average integrated area, endurance, cycle duration, time between cycles, maximum and minimum force-velocity, rate of grip force, final force, inflection point, integrated area, submaximal control, and response time.

CONCLUSIONS

Various indicators based on the force-time curve can be assessed through digital or adapted dynamometers. Future research should analyze these indicators to understand their implications for muscle function assessment, to standardize evaluation procedures, to identify clinically relevant measures, and to clarify their implications in clinical practice.

Assessment of Cognitive Function in European Adults Aged 50+in Relation to Their Handgrip Strength and Physical Inactivity: The SHARE Study During 2019-2020

BACKGROUND

Cognitive function is crucial during aging. This study assessed the cognitive function of European adults aged 50 and over in relation to handgrip strength and physical inactivity. Study Design: This was a cross-sectional survey.

METHODS

Data were collected from 41,395 adults from 27 European countries participating in the Survey of Health, Ageing, and Retirement in Europe (SHARE) during 2019-2020. Cognitive function was assessed based on five tests, and cognitive impairment was defined using 3+tests. Handgrip strength and physical inactivity were also correlated through the analysis of covariance using a complex study design.

RESULTS

The majority of participants were female (56.6%), with a mean age of 70.9 years, and 22.6% presented multimorbidity. Furthermore, 51.1% had a normal cognitive function, while 13.3% had cognitive impairment (The estimated population was 21,944,722). Moreover, cognitive impairment was more prevalent in females than in males (14.4% vs. 12.0%, P<0.001) in patients with no years of education (P<0.001) and origin from southern European countries (P<0.001). Additionally, participants with cognitive impairment had lower mean handgrip strength compared to those with cognitive impairment in 1-2 criteria or with normal cognitive function (29.3 vs. 33.4 and 35.1 kg, respectively, P<0.001). Physically inactive participants had higher odds ratio (OR) of cognitive impairment than those engaging in moderate/vigorous physical activity, both in 1-2 tests (OR:1.73, 95% confidence interval (CI): 1.32-2.26) and in 3+tests (OR: 3.36, 95% CI: 2.57-4.40).

CONCLUSION

Cognitive impairment presented low prevalence and was associated with low levels of handgrip strength and physical inactivity. These specific factors may play a special role in early detection, diagnosis, and treatment or may slow down the progression of cognitive impairment.

Aerobic exercise attenuates LPS-induced cognitive dysfunction by reducing oxidative stress, glial activation, and neuroinflammation

Physical activity has been considered an important non-medication intervention in preserving mnemonic processes during aging. However, how aerobic exercise promotes such benefits for human health remains unclear. In this study, we aimed to explore the neuroprotective and anti-inflammatory effects of aerobic exercise against lipopolysaccharide (LPS)-induced amnesic C57BL/6J mice and BV-2 microglial cell models. In the in vivo experiment, the aerobic exercise training groups were allowed to run on a motorized treadmill 5 days/week for 4 weeks at a speed of 10 rpm/min, with LPS (0.1 mg/kg) intraperitoneally injected once a week for 4 weeks. We found that aerobic exercise ameliorated memory impairment and cognitive deficits among the amnesic mice. Correspondingly, aerobic exercise significantly increased the protein expressions of FNDC5, which activates target neuroprotective markers BDNF and CREB, and antioxidant markers Nrf2/HO-1, leading to inhibiting microglial-mediated neuroinflammation and reduced the expression of BACE-1 in the hippocampus and cerebral cortex of amnesic mice. We estimated that aerobic exercise inhibited neuroinflammation in part through the action of FNDC5/irisin on microglial cells. Therefore, we explored the anti-inflammatory effects of irisin on LPS-stimulated BV-2 microglial cells. In the in vitro experiment, irisin treatment blocked NF-κB/MAPK/IRF3 signaling activation concomitantly with the significantly lowered levels of the LPS-induced iNOS and COX-2 elevations and promotes the Nrf2/HO-1 expression in the LPS-stimulated BV-2 microglial cells. Together, our findings suggest that aerobic exercise can improve the spatial learning ability and cognitive functions of LPS-treated mice by inhibiting microglia-mediated neuroinflammation through its effect on the expression of BDNF/FNDC5/irisin.

Relationships between muscle strength, lung function, and cognitive function in Chinese middle-aged and older adults: A study based on the China health and retirement longitudinal study (CHARLS)

OBJECTIVE

As the population ages, concerns about cognitive decline have become increasingly relevant in medical consultations. This study aims to analyze the interaction between muscle strength, lung function, and cognitive function in Chinese middle-aged and older adults, providing a theoretical basis for better prevention of cognitive decline.

METHODS

This study used data from the China Health and Retirement Longitudinal Study (CHARLS) wave 3, including 13 716 participants aged 45 years or older. Cognitive function was assessed through two dimensions, resulting in a total score ranging from 0 to 31 points, with higher scores indicating better cognitive function. Muscle strength was measured using normalized grip strength and chair-standing time, while lung function was evaluated using peak expiratory flow (PEF).

RESULTS

Total cognitive function scores exhibited significant correlations with grip strength, chair-standing time, and PEF. Muscle strength and lung function demonstrated significant associations with cognitive function, with lung function emerging as a notable mediating factor. This relationship persisted even after adjusting for potential confounding variables. Specifically, PEF played a substantial mediating role in linking grip strength to cognitive function scores (estimated indirect effect = 0.0132, boot-strapped standard error = 0.0015, boot-strapped standard 95% confidence interval = 0.0104, 0.0162). Additionally, PEF served as a significant mediator in the association between chair-standing time and cognitive function scores (estimated indirect effect = -0.0204, boot-strapped standard error = 0.0023, boot-strapped standard 95% confidence interval = -0.0251, -0.0159).

CONCLUSION

The study highlights the importance of addressing declines in muscle strength and lung function to identify risk factors associated with cognitive function. Understanding these relationships can provide insights into potential pathways linking these variables and may aid in better prevention of cognitive decline. Further long-term longitudinal cohort studies are needed to explore the causality between these factors.

Biomarkers of Physical and Mental Health for Prediction of Parkinson's Disease: A Population-Based Study from 15 European Countries

OBJECTIVES

Early diagnosis of Parkinson's disease (PD) is critical for optimal treatment. However, the predictive potential of physical and mental health in PD is poorly characterized.

METHODS

We evaluated the potential of multiple demographic, physical, and mental factors in predicting the future onset of PD in older adults aged 50 years or older from 15 European countries. Individual study participants were followed over four waves of the Survey of Health, Ageing, and Retirement in Europe (SHARE) from 2013-2020.

RESULTS

Of 57,980 study participants, 442 developed PD during the study period. We identified male sex and advancing age from the sixth decade of life onward as significant predictors of future PD. Among physical factors, a low handgrip strength (HGS; men <27 kg, women <16 kg), being bothered by frailty, and recent falls were significantly associated with future PD. Among mental factors, a higher depression (Euro-D depression score >6) emerged as an independent predictor of future PD. Finally, the presence of hypertension or Alzheimer's disease (AD) increases the risk of future PD.

CONCLUSIONS

Altogether, male sex, advancing age, low HGS, frailty, depression, hypertension, and AD were identified as critical risk factors for future PD. Our results may be useful in the early identification and treatment of populations at risk for PD.

Size or Strength? how components of muscle relate to behavioral and neuroelectric measures of executive function independent of aerobic fitness

While previous research has linked cognitive function with resistance exercise, the nuanced links between muscle strength, mass, and neuroelectric function are less understood. Therefore, this study investigated the association of muscle strength and mass with inhibitory control (IC), working memory (WM), and related neuroelectric activity. A total of 123 18-50-year-old adults completed maximal aerobic capacity and strength tests, a body composition scan, and IC and WM tasks while the N2 and P3 components of event-related potentials were recorded. Bivariate correlations revealed aerobic fitness, strength, and mass were associated with behavioral and neuroelectric outcomes. After accounting for age, sex, and aerobic fitness, strength was associated with intra-individual response time variability, accuracy, and P3 latency during WM. Muscle mass was associated with N2 latency during IC. While relationships with behavioral outcomes did not persist after controlling for the opposite muscle outcome, greater strength and mass were related to shorter P3 latency during WM and shorter N2 latency during IC, respectively. These results provide initial evidence that muscle outcomes are associated with executive function and neuroelectric processing speed, suggesting distinct contributions of strength and mass to cognition. This work highlights the significance of maintaining muscle strength and mass alongside aerobic fitness for optimal cognitive health.

Association between dynapenia and cognitive decline in community-dwelling older Japanese adults: The IRIDE Cohort Study

AIM

Muscle mass and strength correlate with cognitive function; however, it remains unclear whether dynapenia (i.e., muscle weakness with preserved muscle mass) is relevant. This study aimed to explore whether dynapenia is associated with global cognitive function in community-dwelling older Japanese adults.

METHODS

This cross-sectional study used data from the Integrated Research Initiative for Living Well with Dementia Cohort Study, which pooled data from five community-based geriatric cohorts. Dynapenia was defined as muscle weakness without muscle mass loss according to the Asian Working Group for Sarcopenia criteria. Cognitive function was assessed using the Mini-Mental State Examination (MMSE). An ordered logistic regression analysis was conducted with dynapenia as the exposure and with cognitive decline stages, defined as an MMSE score of 27-30 for normal cognition, 24-26 for possible cognitive decline, and <24 for cognitive decline, as the outcome, stratified by sex and adjusted for age, muscle mass, education, alcohol consumption, smoking habits, living alone, and non-communicable diseases.

RESULTS

We analyzed data for 3338 participants (2162 female) with preserved muscle mass. Of these, 449 (13.5%) had dynapenia, and 79 (2.4%) exhibited cognitive decline. Multivariate odds ratios (95% confidence interval) for cognitive decline among those with dynapenia, compared with those without dynapenia, were 1.51 (1.02-2.24) for males and 2.08 (1.51-2.86) for females.

CONCLUSIONS

Muscle weakness is associated with cognitive decline, even in individuals with preserved muscle mass. Further studies are needed to better understand the association between muscle weakness and cognitive decline over time in order to develop dementia prevention strategies for those with dynapenia. Geriatr Gerontol Int 2024; 24: 123-129.

Higher handgrip strength is linked to higher salience ventral attention functional network segregation in older adults

Converging evidence suggests that handgrip strength is linked to cognition in older adults, and this may be subserved by shared age-related changes in brain function and structure. However, the interplay among handgrip strength, brain functional connectivity, and cognitive function remains poorly elucidated. Hence, our study sought to examine these relationships in 148 community-dwelling older adults. Specifically, we examined functional segregation, a measure of functional brain organization sensitive to ageing and cognitive decline, and its associations with handgrip strength and cognitive function. We showed that higher handgrip strength was related to better processing speed, attention, and global cognition. Further, higher handgrip strength was associated with higher segregation of the salience/ventral attention network, driven particularly by higher salience/ventral attention intra-network functional connectivity of the right anterior insula to the left posterior insula/frontal operculum and right midcingulate/medial parietal cortex. Importantly, these handgrip strength-related inter-individual differences in salience/ventral attention network functional connectivity were linked to cognitive function, as revealed by functional decoding and brain-cognition association analyses. Our findings thus highlight the importance of the salience/ventral attention network in handgrip strength and cognition, and suggest that inter-individual differences in salience/ventral attention network segregation and intra-network connectivity could underpin the handgrip strength-cognition relationship in older adults.

Hand Grip Strength, Osteoporosis, and Quality of Life in Middle-Aged and Older Adults

Background and Objectives: Hand grip strength (HGS) and osteoporosis are known to be closely related to the health condition of the elderly, respectively. Comprehensive studies including adults over middle age were insufficient. This study aimed to investigate the relationship between HGS with osteoporosis and health-related quality of life (HRQoL) in adults aged >40 years. Materials and Methods: This cross-sectional analysis included data from 13,966 people aged >40 years between 2015 to 2018 provided by the Korea National Health and Nutrition Examination Survey. The HGS was divided into strong and weak quartiles, defined as the highest and lowest quartiles, respectively. We used the European Quality of Life Scale-Five dimensions (EQ-5D) for HRQoL. We performed multiple logistic regression and post hoc analysis to confirm the relationship between the four groups and HRQoL. Results: Osteoporotic patients with weak HGS showed the lowest EQ-5D index (0.87 ± 0.01) among all groups and had a significantly impaired HRQoL in all EQ-5D dimensions, at least 1.75 times more than healthy individuals with strong HGS (0.95 ± 0.00). Osteoporotic patients with weak HGS showed, notably, 2.68 times more impaired mobility compared to healthy individuals with strong HGS among all five dimensions of the EQ-5D. In self-care, significant sex differences in impaired HRQoL were observed (males 6.03, 2.23-16.35; females 2.51, 1.70-3.71). Conclusions: Weak HGS and the presence of osteoporosis were associated with low HRQoL, respectively. Middle-aged and older adults with both weak HGS and osteoporosis showed poorer HRQoL compared to healthy middle-aged and older adults. This suggests that HGS is a possible factor for predicting poor HRQoL in adults aged >40 years with or without osteoporosis. It is necessary to assess the risk of low HRQoL by measuring HGS and confirming whether osteoporosis is accompanied in adults over middle age.

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.

Lower handgrip strength in short-sleeper individuals with obstructive sleep apnea

BACKGROUND

Obstructive sleep apnea (OSA) is a frequently observed and remarkably incapacitating disorder worldwide. As a multisystem disorder, OSA has been linked to a plethora of clinical parameters though physical parameters like muscle strength have been scantily studied. Hand grip strength (HGS) is a practical marker of physical function that has been associated with mortality and an array of clinical outcomes as well as physiological parameters like sleep duration. A few seminal studies have observed no link between HGS and OSA severity while no studies evaluated the relationship between objectively determined sleep duration and HGS in OSA.

OBJECTIVE

The present study aimed to evaluate the HGS indices among both OSA severity groups and objectively determined sleep duration groups in OSA.

METHODS

111 treatment-naïve mostly middle-aged individuals with OSA (86 males) were recruited in a tertiary sleep center. Three OSA severity groups were determined by the Apnea-Hypopnea Index while three sleep duration groups were objectively determined by Total Sleep Time (TST). Dominant and non-dominant maximum and average HGS were calculated using a digital hand dynamometer.

RESULTS

Short-sleeper individuals with OSA were found to have lower HGS indices than intermediate or sufficient sleepers with OSA while no differences in HGS indices among OSA severity groups were observed. All HGS indices correlated with TST.

CONCLUSIONS

Future insights can be gleaned from the present results regarding the conceivably transdiagnostic relationship between sleep duration and HGS as well as the potential use of HGS as a marker in OSA.

The Role of Different Weakness Cut-Points for Future Cognitive Impairment in Older Americans

OBJECTIVES

New absolute and normalized handgrip strength (HGS) cut-points may not yield similar predictive value for cognitive performance. We sought to determine the associations of (1) each absolute and normalized weakness cut-point, and (2) compounding weakness on future cognitive impairment in older Americans.

DESIGN

Longitudinal panel.

SETTING AND PARTICIPANTS

The analytic sample included 11,116 participants aged ≥65 years from the 2006 to 2018 waves of the Health and Retirement Study. Participants from the Health and Retirement Study completed detailed interviews that included physical measures and core interviews.

METHODS

The modified Telephone Interview of Cognitive Status assessed cognitive function and persons scoring <11 were classified as having a cognitive impairment. A handgrip dynamometer measured HGS. Men were considered weak if their HGS was <35.5 kg (absolute), <0.45 kg/kg (body mass normalized), or <1.05 kg (body mass index normalized), whereas women were classified as weak if their HGS was <20.0 kg, <0.337 kg/kg, or <0.79 kg. Compounding weakness included those below 1, 2, or all 3 cut-points. Generalized estimating equations quantified the associations.

RESULTS

Persons considered weak under the absolute cut-point had 1.62 (95% CI 1.34-1.96) greater odds for future cognitive impairment, but no significant associations were observed for those classified as weak under the body mass [odds ratio (OR) 1.12, CI 0.91-1.36] and body mass index normalized (OR 1.17, CI 0.95-1.43) cut-points. Older Americans below all 3 weakness cut-points had 1.47 (CI 1.15-1.88) greater odds for future cognitive impairment, but no significant associations were found for persons classified as weak under 1 (OR 1.08, CI 0.83-1.42) or 2 (OR 1.19, CI 0.91-1.55) cut-points.

CONCLUSIONS AND IMPLICATIONS

Our findings suggest that each weakness cut-point has differential prognostic value for future cognitive impairment, and aggregating weakness cut-points may improve their predictive utility. Consideration should be given to how weakness categories are uniquely linked to cognitive function.

Does muscle strength predict working memory? A cross-sectional fNIRS study in older adults

Objective

Previous research has primarily focused on the association between muscle strength and global cognitive function in older adults, while the connection between muscle strength and advanced cognitive function such as inhibition and working memory (WM) remains unclear. This study aimed to investigate the relationship among muscle strength, WM, and task-related cortex hemodynamics.

Methods

We recruited eighty-one older adults. Muscle strength was measured using a grip and lower limb strength protocol. We measured the WM performance by using reaction time (RT) and accuracy (ACC) in the N-back task and the cortical hemodynamics of the prefrontal cortex (PFC) by functional near-infrared spectroscopy (fNIRS).

Results

We found positive correlations between grip strength (p < 0.05), 30-s sit-up (p < 0.05) and ACC, negative correlation between grip strength (p < 0.05) and RT. Furthermore, we observed positive correlations between grip strength and the level of oxygenated hemoglobin (HbO2) in dorsolateral prefrontal cortex, frontopolar area, ventrolateral prefrontal cortex (p < 0.05), and negative correlations between grip strength and the level of deoxygenated hemoglobin (Hb) in left dorsolateral prefrontal cortex, frontopolar area, left ventrolateral prefrontal cortex (p < 0.05). Additionally, we noticed positive correlations between RT and the level of Hb in left dorsolateral prefrontal cortex, right frontopolar area (p < 0.05), and negative correlations between RT and the level of HbO2 in left dorsolateral prefrontal cortex, frontopolar area (p < 0.05). However, the cortical hemodynamics did not mediate the relationship between muscle strength and WM performance (RT, ACC).

Conclusion

The grip strength of older adults predicted WM in the cross-section study. The level of hemodynamics in PFC can serve as a predictor of WM.

Look into my eyes: What can eye-based measures tell us about the relationship between physical activity and cognitive performance?

BACKGROUND

There is a growing interest to understand the neurobiological mechanisms that drive the positive associations of physical activity and fitness with measures of cognitive performance. To better understand those mechanisms, several studies have employed eye-based measures (e.g., eye movement measures such as saccades, pupillary measures such as pupil dilation, and vascular measures such as retinal vessel diameter) deemed to be proxies for specific neurobiological mechanisms. However, there is currently no systematic review providing a comprehensive overview of these studies in the field of exercise-cognition science. Thus, this review aimed to address that gap in the literature.

METHODS

To identify eligible studies, we searched 5 electronic databases on October 23, 2022. Two researchers independently extracted data and assessed the risk of bias using a modified version of the Tool for the assEssment of Study qualiTy and reporting in EXercise (TESTEX scale, for interventional studies) and the critical appraisal tool from the Joanna Briggs Institute (for cross-sectional studies).

RESULTS

Our systematic review (n = 35 studies) offers the following main findings: (a) there is insufficient evidence available to draw solid conclusions concerning gaze-fixation-based measures; (b) the evidence that pupillometric measures, which are a proxy for the noradrenergic system, can explain the positive effect of acute exercise and cardiorespiratory fitness on cognitive performance is mixed; (c) physical training- or fitness-related changes of the cerebrovascular system (operationalized via changes in retinal vasculature) are, in general, positively associated with cognitive performance improvements; (d) acute and chronic physical exercises show a positive effect based on an oculomotor-based measure of executive function (operationalized via antisaccade tasks); and (e) the positive association between cardiorespiratory fitness and cognitive performance is partly mediated by the dopaminergic system (operationalized via spontaneous eye-blink rate).

CONCLUSION

This systematic review offers confirmation that eye-based measures can provide valuable insight into the neurobiological mechanisms that may drive positive associations between physical activity and fitness and measures of cognitive performance. However, due to the limited number of studies utilizing specific methods for obtaining eye-based measures (e.g., pupillometry, retinal vessel analysis, spontaneous eye blink rate) or investigating a possible dose-response relationship, further research is necessary before more nuanced conclusions can be drawn. Given that eye-based measures are economical and non-invasive, we hope this review will foster the future application of eye-based measures in the field of exercise-cognition science.

Preoperative low handgrip strength (HGS) with HGS asymmetry is associated with adverse outcomes among older adults with gastric cancer

INTRODUCTION

This study aimed to explore the associations of low hand grip strength (HGS), HGS asymmetry, their combinations, and frailty on hospital readmissions, total complications, and prolonged length of stay (PLOS) among older adults with gastric cancer.

MATERIALS AND METHODS

This study included 342 patients with gastric cancer aged ≥60 years who were scheduled to undergo radical surgery. The Tilburg Frailty Indicator (TFI) was used to collect information on frailty. HGS was measured twice for each hand using an electronic handgrip dynamometer. The highest HGS readings on each hand were used for calculating the HGS asymmetry ratio: non-dominant HGS (kg)/dominant HGS (kg). The Fine and Gray proportional subdistribution hazard model and the logistic regression model were used for the analyses, with covariates adjusted.

RESULTS

Low HGS (subdistribution hazard ratios [SHR] = 2.10, 95% confidence interval [CI] = 1.05-3.93, P = 0.036) and low HGS with HGS asymmetry (SHR = 3.95, 95% CI = 1.50-10.36, P = 0.005) were significantly associated with hospital readmissions. Frailty was associated with total complications (odds ratio [OR] = 2.87, 95% CI = 1.61-5.13, P < 0.001) and PLOS (OR = 1.98, 95% CI = 1.19-3.29, P < 0.001). Low HGS, HGS asymmetry, and their combinations were not significantly associated with total complications and PLOS.

DISCUSSION

Preoperative low HGS and low HGS with HGS asymmetry were associated with hospital readmissions, while frailty was associated with total complications and PLOS among older adults with gastric cancer. In the future, more rigorously designed studies are needed to verify our results further to improve preoperative clinical assessment and frailty evaluation among older adults with gastric cancer.

The Effects of 12-Week Dual-Task Physical-Cognitive Training on Gait, Balance, Lower Extremity Muscle Strength, and Cognition in Older Adult Women: A Randomized Study

This study aims to investigate the effects of dual-task physical-cognitive the training on body balance (BB), gait performance (GP), lower limb muscle strength (LEMS), and cognitive performance (CP) in a group of cognitively normal older adult women (n = 44; 66.20 ± 4.05 years). Of these, 22 were randomly allocated to the dual-task training (DT) group, and 22 participated in the control group (CG). Assessments were performed at baseline, after 12 weeks of intervention, and at the end of 12 weeks of follow-up, using the following instruments: Timed Up & Go (TUG), Timed Up & Go manual (TUGm), Timed Up & Go cognitive (TUGc), Balance Test (TEC), sit-to-stand test (STS), and verbal fluency test (VF). After 12 weeks of DT training, participants showed a significant time × group interaction in all motor assessments (BB, GP, LEMS), as well as in three cognitive tests (VF-grouping, VF-exchange, VF-total). No time-group interaction effect was indicated for the VF-category test. At all evaluation times, CG members maintained constant physical and cognitive performance. We conclude that 12 weeks of physical-cognitive DT training was effective in promoting BB, GP, and LEMS, as well as CP in cognitively normal older adult women, with lasting effects up to 12 weeks after the intervention.

Whole body-electromyostimulation effects on serum biomarkers, physical performances and fatigue in Parkinson's patients: A randomized controlled trial

Background

Whole-body electromyostimulation (WB-EMS) was never previously applied to Parkinson's disease (PD) patients. This randomized controlled study aimed to find the most effective and safe WB-EMS training protocol for this population.

Methods

Twenty-four subjects (age: 72.13 ± 6.20 years), were randomly assigned to three groups: a high-frequency WB-EMS strength training group (HFG) (rectangular stimulation at 85 Hz, 350 μs, 4 s stimulation/4 s rest), a low-frequency WB-EMS aerobic training group (LFG) (rectangular stimulation 7 Hz, 350 μs, with a continuous pulse duration), and an inactive control group (CG). Participants of the two experimental groups underwent 24 controlled WB-EMS training sessions, with a duration of 20 min each, during 12-week intervention. Serum growth factors (BDNF, FGF-21, NGF and proNGF), α-synuclein, physical performance and Parkinson's Disease Fatigue Scale (PFS-16) responses were analyzed to evaluate the pre-post variation and differences among groups.

Results

Significant interactions of Time*Groups were detected for BDNF (Time*Groups p = 0.024; Time*CG, b = -628, IC95% = -1,082/-174, p = 0.008), FGF-21 (Time*Groups p = 0.009; Time*LFG b = 1,346, IC95% = 423/2268, p = 0.005), and α-synuclein (Time*Groups p = 0.019; Time*LFG b = -1,572, IC95% = -2,952/-192, p = 0.026). Post hoc analyses and comparisons of ΔS (post-pre), performed independently for each group, showed that LFG increased serum BDNF levels (+ 203 pg/ml) and decreased α-synuclein levels (-1,703 pg/ml), while HFG showed the opposite effects (BDNF: -500 pg/ml; α-synuclein: + 1,413 pg/ml). CG showed a significant BDNF reduction over time. Both LFG and HFG showed significant improvements in several physical performance outcomes and the LFG showed better results than HFG. Concerning PFS-16, significant differences over time (b = -0.4, IC95% = -0.8/-0.0, p = 0.046) and among groups (among all groups p < 0.001) were found, and the LFG exhibited better results than the HFG (b = -1.0, IC95% = -1.3/-0.7, p < 0.001), and CG (b = -1.7, IC95% = -2.0/-1.4, p < 0.001) with this last one that worsened over time.

Conclusion

LFG training was the best choice for improving or maintaining physical performance, fatigue perception and variation in serum biomarkers.

Clinical trial registration

https://www.clinicaltrials.gov/ct2/show/NCT04878679, identifier NCT04878679.

Relationship Between Cognitive Performance, Physical Activity, and Socio-Demographic/Individual Characteristics Among Aging Americans

BACKGROUND

Physical activity (PA) has emerged as a promising approach to delay Alzheimer's disease and related dementias, but the optimal intensity of PA to improve cognitive health remains unknown.

OBJECTIVE

To evaluate the association between duration and intensity of PA and cognitive domains (executive function, processing speed, and memory) in aging Americans.

METHODS

Linear regressions in hierarchical blocks for variable adjustment and the size of effect (η2) were analyzed by using the data of 2,377 adults (age = 69.3±6.7 years) from the NHANES 2011-2014.

RESULTS

Participants with 3-6 h/week of vigorous- and > 1 h/week of moderate-intensity PA scored significantly higher in executive function and processing speed domains of cognition compared to inactive peers (η2 = 0.005 & 0.007 respectively, p < 0.05). After adjustment, the beneficial effects of 1-3 h /week of vigorous-intensity PA became trivial for delayed recall memory domain test scores (β= 0.33; 95% CI: -0.01,0.67; η2 = 0.002; p = 0.56). There was no linear dose-response relationship between the cognitive test scores and weekly moderate-intensity of PA. Interestingly, higher handgrip strength and higher late-life body mass index were associated with a higher performance across all cognitive domains.

CONCLUSION

Our study supports habitual PA with superior cognition health in some but not all domains among older adults. Furthermore, increased muscle strength and higher late-life adiposity may also impact cognition.

Effect of isometric handgrip exercise on cognitive function: Current evidence, methodology, and safety considerations

Cognitive function is essential for most behaviors of daily living and is a critical component in assessing the quality of life. Mounting prospective evidence supports the use of isometric handgrip exercise (IHE) as a small muscle mass practice to promote health-related outcomes in clinical and healthy populations. The aim of the present review was to systematically investigate whether IHE is effective in improving the cognitive function of adults (aged ≥18 years). Studies were identified by searching five databases (CINAHL, MEDLINE, SPORTDiscus, PsychINFO, and Web of Science). Eight out of 767 studies met the inclusion criteria, including three types of studies: 1) acute effect for IHE with various intensity protocols (n = 4); 2) acute effect for IHE with one set exhaustion protocol (n = 2); and 3) chronic effect of IHE on cognitive function (n = 2). To assess the methodological quality of studies, the PEDro scale was used (mean score = 6.75). The evidence on whether IHE exerts acute positive effects on cognitive performance is currently rather inconclusive. However, a trend was discernible that implementing IHE can generate a beneficial chronic effect on cognitive function, although the results should be interpreted with caution. The clinical relevance of IHE as a time-efficient type of physical exercise to improve cognitive function warrants further investigation. Methodology and safety considerations were discussed.

Systematic Review Registration: (https://osf.io/gbzp9).

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.

Undiagnosed Dementia Is Associated with Poor Physical Function in Older Adults

BACKGROUND

Older adults with a cognitive impairment, including those not yet diagnosed, may have deficits in their physical function.

OBJECTIVE

We sought to determine the associations of cognitive impairment consistent with dementia (CICD) diagnosis status on handgrip strength, gait speed, and functional disability in older adults.

METHODS

The analytical sample included 8,383 adults aged ≥65-years without history of stroke, cancers, neurological conditions, or brain damage who participated in at least one-wave of the 2010-2016 waves of the Health and Retirement Study. A handgrip dynamometer measured handgrip strength. Men with handgrip strength <26 kg and women <16 kg were weak. Gait speed was timed across a 2.5-m course and those with slowness had gait speed <0.8 m/s. Participants with difficulty or an inability in completing any basic activities of daily living had a functional disability. The adapted Telephone Interview of Cognitive Status evaluated cognitive function. Persons with scores <7 had a CICD. Healthcare provider dementia-related diagnosis was self-reported. Undiagnosed CICD was defined as no reported dementia-related diagnosis but had CICD, while diagnosed CICD was classified as reporting a dementia-related diagnosis. Covariate-adjusted logistic models were used for the analyses.

RESULTS

Persons with undiagnosed CICD had 1.37 (95% confidence interval (CI): 1.04-1.80) greater odds for weakness and 2.02 (CI: 1.39-2.94) greater odds for slow gait speed. Older adults with diagnosed CICD had 2.29 (CI: 1.32-3.97) greater odds for slowness and 1.85 (CI: 1.19-2.90) greater odds for functional disability.

CONCLUSION

Screening for CICD could be recommended when defects in physical function are observed in older adults.

Handgrip strength and all-cause dementia incidence and mortality: findings from the UK Biobank prospective cohort study

BACKGROUND

This study aimed to investigate the associations of grip strength with incidence and mortality from dementia and whether these associations differ by sociodemographic and lifestyle factors.

METHODS

A total of 466 788 participants of the UK Biobank (median age 56.5 years, 54.5% women). The outcome was all-cause dementia incidence and mortality and the exposure was grip strength. Grip strength was assessed using a Jamar J00105 hydraulic hand dynamometer.

RESULTS

Excluding the first 2 years of follow-up (landmark analysis), mean follow-up was 9.1 years (inter-quartile range: 8.3; 9.7) for incidence and 9.3 (inter-quartile range: 8.7; 10.0) for mortality. During this time, 4087 participants developed dementia, and 1309 died from it. Lower grip strength was associated with a higher risk of dementia incidence and mortality independent of major confounding factors (P < 0.001). Individuals in the lowest quintile of grip strength had 72% [95% confidence interval (CI): 1.55; 1.92] higher incident dementia risk and 87% [95% CI: 1.55; 2.26] higher risk of dementia mortality compared with those in the highest quintile. Our PAF analyses indicate that 30.1% of dementia cases and 32.3% of dementia deaths are attributable to having low grip strength. The association between grip strength and dementia outcomes did not differ by lifestyle or sociodemographic factors.

CONCLUSIONS

Lower grip strength was associated with a higher risk of all-cause dementia incidence and mortality, independently of important confounding factors.

The Relationship Between Muscle Strength and Cognitive Performance Across Alzheimer's Disease Clinical Continuum

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by a progressive cognitive decline, mostly prominent in the domain of memory, but also associated with other cognitive deficits and non-cognitive symptoms. Reduced muscle strength is common in AD. However, the current understanding of its relationship with cognitive decline is limited. This study investigates the relationship between muscle strength and cognition in patients with AD and mild cognitive impairment (MCI). We enrolled 148 consecutive subjects, including 74 patients with probable AD dementia, 37 MCI, and 37 controls. Participants underwent neuropsychological evaluation focused on attention, working memory, declarative memory and learning. Muscle strength and muscle mass were measured through hand dynamometer and bio-electrical impedance analysis, respectively. Patients with AD dementia were divided with respect to the severity of cognitive impairment into mild and moderate-to-severe patients. Moderate-to-severe patients with AD presented lower handgrip strength than MCI and controls. No differences were observed in muscle mass. In MCI and AD dementia, handgrip strength was associated with overall cognitive functioning, attentional and memory performance. The routine implementation of handgrip strength assessment in the clinical work-up of patients with MCI and AD could potentially represent a simple method to monitor functional and cognitive decline along the disease course.

Linking Pain and Motor Control: Conceptualization of Movement Deficits in Patients With Painful Conditions

When people experience or expect pain, they move differently. Pain-altered movement strategies, collectively described here as pain-related movement dysfunction (PRMD), may persist well after pain resolves and, ultimately, may result in altered kinematics and kinetics, future reinjury, and disability. Although PRMD may manifest as abnormal movements that are often evident in clinical assessment, the underlying mechanisms are complex, engaging sensory-perceptual, cognitive, psychological, and motor processes. Motor control theories provide a conceptual framework to determine, assess, and target processes that contribute to normal and abnormal movement and thus are important for physical therapy and rehabilitation practice. Contemporary understanding of motor control has evolved from reflex-based understanding to a more complex task-dependent interaction between cognitive and motor systems, each with distinct neuroanatomic substrates. Though experts have recognized the importance of motor control in the management of painful conditions, there is no comprehensive framework that explicates the processes engaged in the control of goal-directed actions, particularly in the presence of pain. This Perspective outlines sensory-perceptual, cognitive, psychological, and motor processes in the contemporary model of motor control, describing the neural substrates underlying each process and highlighting how pain and anticipation of pain influence motor control processes and consequently contribute to PRMD. Finally, potential lines of future inquiry-grounded in the contemporary model of motor control-are outlined to advance understanding and improve the assessment and treatment of PRMD.

IMPACT

This Perspective proposes that approaching PRMD from a contemporary motor control perspective will uncover key mechanisms, identify treatment targets, inform assessments, and innovate treatments across sensory-perceptual, cognitive, and motor domains, all of which have the potential to improve movement and functional outcomes in patients with painful conditions.

The estimated prevalence of no reported dementia-related diagnosis in older Americans living with possible dementia by healthcare utilization

BACKGROUND

Screening for dementia in relevant healthcare settings may help in identifying low cognitive functioning for comprehensive cognitive assessments and subsequent dementia treatment after diagnosis.

AIMS

This study sought to estimate the prevalence of no reported dementia-related diagnosis in a nationally-representative sample of older Americans with a cognitive impairment consistent with dementia (CICD) by healthcare utilization.

METHODS

The unweighted analytical sample included 1514 Americans aged ≥ 65 years that were identified as having a CICD without history of stroke, cancers, neurological conditions, or brain damage who participated in at least one-wave of the 2010-2016 waves of the Health and Retirement Study. An adapted Telephone Interview of Cognitive Status assessed cognitive functioning. Those with scores ≤ 6 had a CICD. Dementia-related diagnosis was self-reported. Respondents indicated if they visited a physician, received home healthcare, or experienced an overnight nursing home stay in the previous two years.

RESULTS

The prevalence of no reported dementia-related diagnosis in persons with a CICD who visited a physician was 89.9% (95% confidence interval (CI): 85.4%-93.1%). Likewise, the prevalence of no reported diagnosis in those with a CICD who received home healthcare was 84.3% (CI: 75.1-90.5%). For persons with a CICD that had an overnight nursing home stay, the prevalence of no reported dementia-related diagnosis was 83.0% (CI: 69.1-91.4%).

DISCUSSION

Although the prevalence of no reported dementia-related diagnosis in individuals with a CICD differed across healthcare settings, the prevalence was generally high nonetheless.

CONCLUSIONS

We recommend increased awareness and efforts be given to dementia screenings in various clinical settings.

A Link between Handgrip Strength and Executive Functioning: A Cross-Sectional Study in Older Adults with Mild Cognitive Impairment and Healthy Controls

Older adults with amnestic mild cognitive impairment (aMCI) who in addition to their memory deficits also suffer from frontal-executive dysfunctions have a higher risk of developing dementia later in their lives than older adults with aMCI without executive deficits and older adults with non-amnestic MCI (naMCI). Handgrip strength (HGS) is also correlated with the risk of cognitive decline in the elderly. Hence, the current study aimed to investigate the associations between HGS and executive functioning in individuals with aMCI, naMCI and healthy controls. Older, right-handed adults with amnestic MCI (aMCI), non-amnestic MCI (naMCI), and healthy controls (HC) conducted a handgrip strength measurement via a handheld dynamometer. Executive functions were assessed with the Trail Making Test (TMT A&B). Normalized handgrip strength (nHGS, normalized to Body Mass Index (BMI)) was calculated and its associations with executive functions (operationalized through z-scores of TMT B/A ratio) were investigated through partial correlation analyses (i.e., accounting for age, sex, and severity of depressive symptoms). A positive and low-to-moderate correlation between right nHGS (rp (22) = 0.364; p = 0.063) and left nHGS (rp (22) = 0.420; p = 0.037) and executive functioning in older adults with aMCI but not in naMCI or HC was observed. Our results suggest that higher levels of nHGS are linked to better executive functioning in aMCI but not naMCI and HC. This relationship is perhaps driven by alterations in the integrity of the hippocampal-prefrontal network occurring in older adults with aMCI. Further research is needed to provide empirical evidence for this assumption.

Handgrip strength and risk of cognitive outcomes: new prospective study and meta-analysis of 16 observational cohort studies

Handgrip strength (HGS), a measure of muscular strength, might be a risk indicator for cognitive functioning, but the evidence is not consistent. Using a new prospective study and meta-analysis of published observational cohort studies, we aimed to evaluate the prospective associations of HGS with poor cognitive outcomes including cognitive impairment, dementia and Alzheimer's disease (AD). Handgrip strength, measured using a Martin-Balloon-Vigorimeter, was assessed at baseline in a population-based sample of 852 men and women with good cognitive function in the Kuopio Ischemic Heart Disease cohort. Hazard ratios (HRs) with 95% confidence intervals (CIs) were estimated for cognitive outcomes. Relevant published studies were sought in MEDLINE, Embase and Web of Science from inception until October 2021 and pooled using random effects meta-analysis. During a median follow-up of 16.6 years, 229 dementia cases were recorded. Comparing extreme tertiles of HGS, the multivariable adjusted HR (95% CI) for dementia, AD and vascular dementia was 0.77 (0.55-1.07), 0.75 (0.52-1.10) and 0.49 (0.16-1.48), respectively. In a meta-analysis of 16 population-based prospective cohort studies (including the current study) comprising 180,920 participants, the pooled multivariable adjusted relative risks (95% CIs) comparing the top vs bottom thirds of HGS levels were as follows: 0.58 (0.52-0.65) for cognitive impairment; 0.37 (0.07-1.85) for cognitive decline; 0.73 (0.62-0.86) for dementia; 0.68 (0.53-0.87) for AD; and 0.48 (0.32-0.73) for vascular dementia. GRADE quality of evidence ranged from low to very low. Meta-analysis of aggregate prospective data suggests that HGS may be a risk indicator for poor cognitive outcomes such as cognitive impairment, dementia and AD. Systematic review registration: PROSPERO 2021: CRD42021237750.

Mediation and Moderation of Adiposity Indicators for the Association Between Grip Strength and Cardiovascular Disease Risk Scores

Background: This cross-sectional study evaluated mediation or moderation of adiposity indicators on the association between handgrip strength (HGS) and the 10-year cardiovascular disease risk scores (CVDR). Methods: In data of 15,206 Korean adults (6961 men and 8245 women) aged ≥30 years using the Korea National Health and Nutrition Examination Survey, HGS, body mass index (BMI), height, waist circumference, the components of Framingham CVDR, and covariates (sociodemographic factors, health behaviors, perceived stress, health, functional status, and nutritional status) were used. BMI, waist circumference, and waist-to-height ratio were used as adiposity indicators. Gender-specific general linear model and PROCESS Macro were applied. Results: HGS had an inverse association with the CVDR after adjusting for the covariates and BMI (or waist circumference), while adiposity indicators had positive associations with the CVDR after adjusting for the covariates and HGS. Mediation analysis shows indirect effects of adiposity indicators (0.010-0.019, P < 0.05) and direct effect of HGS on the CVDR (-0.08 to -0.09, P < 0.05) after adjusting for the covariates. Moderation analysis reveals positive interactions between HGS and adiposity indicators in the relationship with the CVDR after adjusting for the covariates (P < 0.05). The inverse association between the HGS and the CVDR tended to be stronger with decrease in adiposity levels. Conclusions: Adiposity indicators mediated and moderated the association between HGS and the CVDR in Koreans. The moderating effects indicate that the lower the levels of the adiposity indicators, the stronger the CVDR improvement effect of HGS.

Physical Fitness Plays a Crucial Mediator Role in Relationships Among Personal, Social, and Lifestyle Factors With Adolescents' Cognitive Performance in a Structural Equation Model. The Cogni-Action Project

Background: The beneficial relationship between physical fitness and cognitive performance is affected and modulated by a wide diversity of factors that seem to be more sensitive during the development stage, particularly during early adolescence. This study aimed to examine the role of physical fitness considering the multivariate association between age, health-related quality of life (HRQOL), school vulnerability index (SVI), body mass index z-score (BMIz), physical activity, and sleep problems with the cognitive performance in boys and girls. Method: Participants were 1,196 adolescents aged 10-14 years (50.7% of boys) from Chile. Three physical fitness components and eight cognitive tasks were measured. BMIz was determined using growth references by age and sex, whereas questionaries were used to assess sleep problems, physical activity, and HRQOL. SVI was established according to the score given by the Chilean Government to educational establishments. We performed a structural equation model (SEM) to test multivariate associations among study' variables by sex. Results: Fitness was positively associated with boys' and girls' cognitive performance (β = 0.23 and β = 0.17; p = 0.001, respectively). Moreover, fitness presented a significant mediator role in the relationships between BMIz, SVI, and physical activity with cognitive performance (indirect effect). Additionally, SVI showed a negative association both direct and indirect effect in all three fitness components and all cognitive tasks, being this relationship stronger in girls than in boys. Conclusion: Our findings suggest that physical fitness and all its components play a crucial mediator role in the associations between several factors associated with adolescents' cognitive performance. Thereby, educational and health strategies should prioritise improving physical fitness through physical activity. They also should address other factors such as school vulnerability, obesity, and the early gender gap in a comprehensive approach boosting cognitive performance among early adolescents. Trial registration: Research Registry (ID: researchregistry5791).

Probable sarcopenia is associated with cognitive impairment among community-dwelling older adults: results from the FIBRA study

BACKGROUND

The link between sarcopenia and cognitive impairment has not yet been thoroughly evaluated, especially among older adults.

OBJECTIVE

To evaluate the relationship between probable sarcopenia and cognitive impairment among community-dwelling older adults in two Brazilian cities.

METHODS

Probable sarcopenia was assessed using the EWGSOP2 (2018) criteria. Thus, participants were classified as probably having sarcopenia if they had SARC-F (Strength, Assistance in walking, Rise from a chair, Climb stairs and Falls) ≥4 points and low grip strength. Cognitive function was evaluated through the Mini-Mental State Examination (MMSE), verbal fluency (VF) and clock drawing test (CDT).

RESULTS

In a sample of 529 older adults (mean age 80.8±4.9 years; mean education 4.2±3.67 years; 70.1% women), 27.3% of the participants had SARC-F≥4, 38.3% had low grip strength and 13.6% were classified as probable sarcopenia cases. After adjusting for possible confounders (age, sex, education, depression, diabetes, hypertension, leisure-time physical activity and obesity), probable sarcopenia was found to be associated with impairment in the MMSE (OR 2.52; 95%CI 1.42‒4.47; p=0.002) and in VF (OR 2.17; 95%CI 1.17‒4.01; p=0.014). Low grip strength was found to be associated with impairment in the MMSE (OR 1.83; 95%CI 1.18‒2.82; p=0.006) and in the CDT (OR 1.79; 95%CI 1.18‒2.73; p=0.006). SARC-F scores were found to be associated with impairment in the MMSE (OR 1.90; 95%CI 1.18‒3.06; p=0.008).

CONCLUSION

The results suggested that probable sarcopenia and its components present a significant association with cognitive deficits among community-dwelling older adults. Future longitudinal studies will further explore the causal relationship.

The Beneficial Effects of Cognitive Walking Program on Improving Cognitive Function and Physical Fitness in Older Adults

Exercise and cognitive training can improve the brain-related health of the elderly. We investigated the effects of a cognitive walking program (CWP) involving simultaneous performance of indoor walking and cognitive training on cognitive function and physical fitness compared to normal walking (NW) outdoors. Participants were grouped according to whether they performed regular exercise for at least 3 months prior to the participation in this study. Active participants were assigned to the CWP-active group (CWPAG). Sedentary participants were randomly assigned to the CWP (CWPSG) or NW group (NWSG). CWP and NW were performed for 60 min, 3 times a week, for 6 months. Cognitive function (attention, visuospatial function, memory, and frontal/executive function) and physical fitness (cardiorespiratory fitness, lower extremity muscular strength, and active balance ability) were measured at baseline, 3 months, and 6 months after the program onset. Cognitive function showed improvements over time in all three groups, especially in CWPAG. No clear difference was observed between CWPSG and NWSG. Improvements in all fitness measures were also observed in all three groups. These findings collectively indicate the beneficial effects of CWP, as well as NW, on improving cognitive function and physical fitness in older adults, especially those who are physically active.

Physical fitness and its association with cognitive performance in Chilean schoolchildren: The Cogni-Action Project

This study aimed to establish the association and differences in a diversity of cognitive domains according to cardiorespiratory fitness (CRF), muscular fitness (MF), and speed-agility fitness (S-AF) level in a large sample of Chilean schoolchildren. 1171 Chilean schoolchildren aged 10-14 years participated. CRF, MF, and S-AF were assessed through the ALPHA-fitness test battery. Cognition was evaluated through the NeuroCognitive Performance Test, which involved eight tests related to four main domains: cognitive flexibility (CF), working memory (WM), inhibitory control (IC), and intelligence (IN). Both global (multivariate) and individual (univariate) analyses were performed to determine the differences in cognitive functioning according to low-, middle-, and high-fitness level. The global analyses showed a significant main effect for CRF, F_(16,940)  = 3.08, p ≤ .001 and MF groups, F_(16,953)  = 2.30, p = .002, but not for S-AF, F_(16,948)  = 1.37, p = .105. CRF shows a significant main effect in seven of eight tests, involving CF, WM, IC, and IN domains, whereas MF shows a significant main effect in five of eight tests without association with IN. SA-F shows a significant main effect only with IC. Statistical differences were found between the low- and middle/high-fitness groups but not between the middle- and high-fitness groups. At a global level, both CRF and MF seem to be associated with a higher cognitive profile in scholars; however, at an individual level, all fitness components show a favorable relationship to some cognitive domine. Then, future cognitive developing strategies should consider all fitness components, prioritizing those low-fitness schoolchildren.

The Association between Alcohol Consumption and Grip Strength in a Nationwide Survey

BACKGROUND

Handgrip strength (HGS) is an important predictor of long-term health and physical function. Studies have associated alcohol consumption with HGS but based on inconsistent findings. The Korea National Health and Nutrition Examination Survey (KNHANES) data were analyzed to examine the association between alcohol consumption levels and HGS based on sociodemographic and health-related factors.

METHODS

Using the 2014 to 2018 KNHANES data, alcohol consumption levels (abstinence, moderate, binge, and heavy consumption) and HGS levels (normal vs. weak) were determined in 8,556 men and 10,054 women (age, 49±16 years). Logistic regression analyses were conducted after adjusting for sociodemographic and health-related factors and in subgroups of those factors.

RESULTS

Binge or heavy consumption was reported in 50.2% of men and 22.7% of women, and weak HGS was found in 4.6% of men and 9.9% of women. In the fully adjusted model, weak HGS was associated with binge consumption (odds ratio [OR], 0.51, 95% confidence interval [CI], 0.37-0.71) and heavy consumption (OR, 0.37, 95% CI, 0.22-0.63) in men, and moderate consumption (OR, 0.79, 95% CI, 0.67-0.93) and binge consumption (OR, 0.65, 95% CI, 0.52-0.83) in women. An association between consumption levels and weak HGS was found in both sexes regardless of age (&lt;65 vs. ≥65 years), education/income level, exercise endurance level, presence/absence of co-morbid illness, weight, and the presence/absence of metabolic syndrome.

CONCLUSIONS

Alcohol consumption may be inversely associated with weak HGS, regardless of sociodemographic and health-related factors using the 2014 to 2018 KNHANES data. Further prospective studies are necessary to examine the causality of the association.

Cortical hemodynamics as a function of handgrip strength and cognitive performance: a cross-sectional fNIRS study in younger adults

BACKGROUND

There is growing evidence for a positive correlation between measures of muscular strength and cognitive abilities. However, the neurophysiological correlates of this relationship are not well understood so far. The aim of this study was to investigate cortical hemodynamics [i.e., changes in concentrations of oxygenated (oxyHb) and deoxygenated hemoglobin (deoxyHb)] as a possible link between measures of muscular strength and cognitive performance.

METHODS

In a cohort of younger adults (n = 39, 18-30 years), we assessed (i) handgrip strength by a handhold dynamometer, (ii) short-term working memory performance by using error rates and reaction times in the Sternberg task, and (iii) cortical hemodynamics of the prefrontal cortex (PFC) via functional near-infrared spectroscopy (fNIRS).

RESULTS

We observed low to moderate negative correlations (rp =  ~ - 0.38 to - 0.51; p < 0.05) between reaction time and levels of oxyHb in specific parts of the PFC. Furthermore, we noticed low to moderate positive correlations (rp =  ~ 0.34 to 0.45; p < 0.05) between reaction times and levels of deoxyHb in distinct parts of the PFC. Additionally, higher levels of oxyHb (rp (35) = 0.401; p = 0.014) and lower levels of deoxyHb (rp (34) = - 0.338; p = 0.043) in specific parts of the PFC were linked to higher percentage of correct answers. We also found low to moderate correlations (p < 0.05) between measures of handgrip strength and levels of oxyHb (rp =  ~ 0.35; p < 0.05) and levels of deoxyHb (rp =  ~ - 0.25 to - 0.49; p < 0.05) in specific parts of the PFC. However, there was neither a correlation between cognitive performance and handgrip strength nor did cortical hemodynamics in the PFC mediate the relationship between handgrip strength and cognitive performance (p > 0.05).

CONCLUSION

The present study provides evidence for a positive neurobehavioral relationship between cortical hemodynamics and cognitive performance. Our findings further imply that in younger adults higher levels of handgrip strength positively influence cortical hemodynamics although the latter did not necessarily culminate in better cognitive performance. Future research should examine whether the present findings can be generalized to other cohorts (e.g., older adults).

The association between occupational categories and grip strength in Korean male workers

PURPOSE

This study explored the association between occupational categories and muscle strength using handgrip strength (HGS) while considering sociodemographic and health-related factors in Korean men using a national survey.

METHODS

Using cross-sectional data of 8380 men (59.9 ± 16.6 years of age), the occupational categories held the longest duration and HGS levels (normal vs. weak) were determined. Logistic regression was applied with adjustment for sociodemographic factors, work-related factors (working hours and schedule), and health-related factors (physical activity, sedentary time, resistance exercise, alcohol consumption, smoking status, chronic illness, subjective health status, weight category, metabolic syndrome, and protein intake).

RESULTS

Weak HGS prevalence was lowest in male managerial or professional workers (1.5%) and highest in male skilled agricultural, forestry, fishery, or craft and the related trades workers (16.4%). Compared to male managerial or professional workers, the odds for weak HGS increased in male service/sales workers (OR 2.41; 95% CI 1.45-3.99) and male manual workers [agricultural/forestry/fishery/craft and related trades workers, OR 2.94 (95% CI 1.78-4.83); equipment/machine operating/assembling workers, OR 1.68 (95% CI 1.05-2.71); and elementary workers, OR 3.43 (95% CI 1.95-6.05)] in the fully adjusted model. Regardless of age groups, income, working hours, strength exercise, and sedentary time levels, and chronic illness and metabolic syndrome status, male manual workers were more likely to have weak HGS compared to male non-manual workers.

CONCLUSION

Male manual workers may have a higher risk for weak muscle strength compared to male non-manual workers regardless of sociodemographic, work-related, and health-related factors.

Dynapenia and Low Cognition: A Cross-Sectional Association in Postmenopausal Women

Dynapenia is a key contributor to physical frailty. Cognitive impairment and dementia accompany frailty, yet links between skeletal muscle and neurocognition are poorly understood. We examined the cross-sectional relationship between lower limb muscle strength and global cognitive function. Participants were 127 women aged 51–87 years, from the Geelong Osteoporosis Study. Peak eccentric strength of the hip-flexors and hip abductors was determined using a hand-held dynamometer, and dynapenia identified as muscle strength t-scores < −1. Cognition was assessed using the Mini-Mental State Examination (MMSE), and MMSE scores below the median were rated as low. Associations between dynapenia and low cognition were examined using logistic regression models. Hip-flexor dynapenia was detected in 38 (71.7%) women with low cognition and 36 (48.7%) with good cognition (p = 0.009); for hip abductor dynapenia, the pattern was similar (21 (39.6%) vs. 9 (12.2%); p < 0.001). While the observed difference for hip-flexor strength was attenuated after adjusting for age and height (adjusted Odds Ratio (OR) 1.95, 95%CI 0.86–4.41), low cognition was nearly 4-fold more likely in association with hip abductor dynapenia (adjusted OR 3.76, 95%CI 1.44–9.83). No other confounders were identified. Our data suggest that low strength of the hip abductors and low cognition are associated and this could be a consequence of poor muscle function contributing to cognitive decline or vice versa. As muscle weakness is responsive to physical interventions, this warrants further investigation.

Self-Reported Dementia-Related Diagnosis Underestimates the Prevalence of Older Americans Living with Possible Dementia

BACKGROUND

Dementia screening is an important step for appropriate dementia-related referrals to diagnosis and treat possible dementia.

OBJECTIVE

We sought to estimate the prevalence of no reported dementia-related diagnosis in a nationally representative sample of older Americans with a cognitive impairment consistent with dementia (CICD).

METHODS

The weighted analytical sample included 6,036,224 Americans aged at least 65 years old that were identified as having a CICD without history of stroke, cancers, neurological conditions, or brain damage who participated in at least one-wave of the 2010-2016 Health and Retirement Study. The adapted Telephone Interview of Cognitive Status assessed cognitive functioning. Those with scores≤6 were considered as having a CICD. Healthcare provider dementia-related diagnosis was self-reported. Age, sex, educational achievement, and race and ethnicity were also self-reported.

RESULTS

The overall estimated prevalence of no reported dementia-related diagnosis for older Americans with a CICD was 91.4%(95%confidence interval (CI): 87.7%-94.1%). Persons with a CICD who identified as non-Hispanic black had a high prevalence of no reported dementia-related diagnosis (93.3%; CI: 89.8%-95.6%). The estimated prevalence of no reported dementia-related diagnosis was greater in males with a CICD (99.7%; CI: 99.6%-99.8%) than females (90.2%; CI: 85.6%-93.4%). Moreover, the estimated prevalence of no reported dementia-related diagnosis for non-high school graduates with a CICD was 93.5%(CI: 89.3%-96.1%), but 90.9%(CI: 84.7%-94.7%) for those with at least a high school education.

CONCLUSION

Dementia screening should be encouraged during routine geriatric health assessments. Continued research that evaluates the utility of self-reported dementia-related measures is also warranted.

Evaluating Additional Aspects of Muscle Function with a Digital Handgrip Dynamometer and Accelerometer for Cognitive Functioning in Older Adults: A Pilot Study

Handgrip dynamometers are used to assess handgrip strength (HGS), and low HGS is linked to poor cognitive function. Although HGS is a reliable measure of muscle function, it is only measuring maximal grip force. Other aspects of muscle function such as force control, fatigability, and steadiness are unaccounted for in current HGS protocols. This pilot study sought to determine the role of maximal HGS, submaximal HGS force control, HGS fatigability, and HGS neuromuscular steadiness on cognitive function in older adults. Our findings indicate that these additional HGS measurements could factor into detecting poorer cognitive functioning, while also evolving HGS protocols.