Lean mass, grip strength, and hospital-associated disability among older adults in Health ABC

Glyphosate exposure, muscular health and functional limitations in middle-aged and older adults

BACKGROUND

Glyphosate is the most widely used herbicide worldwide, both in domestic and industrial settings. Experimental research in animal models has demonstrated changes in muscle physiology and reduced contractile strength associated with glyphosate exposure, while epidemiological studies have shown associations between glyphosate exposure and adverse health outcomes in critical biological systems affecting muscle function.

METHODS

This study used data from a nationally representative survey of the non-institutionalized U.S. general population (NHANES, n = 2132). Urine glyphosate concentrations were determined by ion chromatography with tandem mass spectrometry. Hand grip strength (HGS) was measured using a Takei Dynamometer, and relative strength estimated as the ratio between HGS in the dominant hand and the appendicular lean mass (ALM) to body mass index (ALMBMI) ratio. Low HGS and low relative HGS were defined as 1 sex-, age- and race-specific SD below the mean. Physical function limitations were identified as significant difficulty or incapacity in various activities.

RESULTS

In fully-adjusted models, the Mean Differences (MD) and 95% confidence intervals [95%CI] per doubling increase in glyphosate concentrations were -0.55 [-1.09, -0.01] kg for HGS in the dominant hand, and -0.90 [-1.58. -0.21] kg for HGS/ALMBMI. The Odds Ratios (OR) [95% CI] for low HGS, low relative HGS and functional limitations by glyphosate concentrations were 1.27 [1.03, 1.57] for low HGS; 1.43 [1.05; 1.94] for low relative HGS; 1.33 [1.08, 1.63] for stooping, crouching or kneeling difficulty; 1.17 [0.91, 1.50] for lifting or carrying items weighting up to 10 pounds difficulty; 1.21 [1.01, 1.40] for standing up from armless chair difficulty; and 1.47 [1.05, 2.29] for ascending ten steps without pause difficulty.

CONCLUSIONS

Glyphosate exposure may be a risk factor for decreased grip strength and increased physical functional limitations. More studies investigating the influence of this and other environmental pollutants on functional aging are needed.

Is inflammation a missing link between relative handgrip strength with hyperlipidemia? Evidence from a large population-based study

BACKGROUND

Relative handgrip strength (RHGS) was positively correlated with healthy levels of cardiovascular markers and negatively correlated with metabolic disease risk. However, its association with hyperlipidemia remains unknown. The present study investigated the link between RHGS and hyperlipidemia, utilizing data from the National Health and Nutrition Examination Survey (NHANES) and further examined the hypothesis that inflammation may serve a mediating role within this relationship.

METHODS

Data were extracted from 4610 participants in the NHANES database spanning 2011-2014 to explore the correlation between RHGS and hyperlipidemia using multivariate logistic regression models. Subgroup analyses were conducted to discern the correlation between RHGS and hyperlipidemia across diverse populations. Additionally, smooth curve fitting and threshold effect analysis were conducted to validate the association between RHGS and hyperlipidemia. Furthermore, the potential mediating effect of inflammation on this association was also explored.

RESULTS

According to the fully adjusted model, RHGS was negatively correlated with hyperlipidemia [odds ratio (OR) = 0.575, 95% confidence interval (CI) = 0.515 to 0.643], which was consistently significant across all populations, notably among women. Smooth curve fitting and threshold effect analysis substantiated the negative association between RHGS and hyperlipidemia. Moreover, the mediating effects analysis indicated the white blood cell (WBC) count, neutrophil (Neu) count, and lymphocyte (Lym) count played roles as the mediators, with mediation ratios of 7.0%, 4.3%, and 5.0%, respectively.

CONCLUSIONS

This study identified a prominent negative correlation between RHGS and hyperlipidemia. Elevated RHGS may serve as a protective factor against hyperlipidemia, potentially through mechanisms underlying the modulation of inflammatory processes.

Association of grip strength and walking pace with the risk of incident Parkinson's disease: a prospective cohort study of 422,531 participants

BACKGROUND

Muscle weakness is a prominent feature of Parkinson's disease, but whether the occurrence of this deficit in healthy adults is associated with subsequent PD diagnosis remains unclear.

OBJECTIVE

This study sought to examine the relationship between muscle strength, represented by grip strength and walking pace, and the risk of incident PD.

METHODS

A total of 422,531 participants from the UK biobank were included in this study. Longitudinal associations of grip strength and walking pace with the risk of incident PD were investigated by Cox proportional hazard models adjusting for several well-established risk factors. Subgroup and sensitivity analyses were also conducted for further validation.

RESULTS

After a median follow-up of 9.23 years, 2,118 (0.5%) individuals developed incident PD. For per 5 kg increment of absolute grip strength, there was a significant 10.2% reduction in the risk of incident PD (HR = 0.898, 95% CI [0.872-0.924], P < 0.001). Similarly, per 0.05 kg/kg increment of relative grip strength was related to a 9.2% reduced risk of incident PD (HR = 0.908, 95% CI [0.887-0.929], P < 0.001). Notably, the associations remained consistent when grip strength was calculated as quintiles. Moreover, participants with a slower walking pace demonstrated an elevated risk of incident PD (HR = 1.231, 95%CI [1.075-1.409], P = 0.003). Subgroup and sensitivity analyses further validated the robustness of the observed associations.

CONCLUSION

Our findings showed a negative association of grip strength and walking pace with the risk of incident PD independent of important confounding factors. These results hold potential implications for the early screening of people at high-risk of PD.

Low hemoglobin levels are associated with compromised muscle health: Insights from a post-stroke rehabilitation cohort

AIM

There is limited evidence concerning the association between anemia and alterations in muscle health among hospitalized older patients. We aimed to evaluate the associations between baseline hemoglobin (Hb) levels and changes in muscle function in patients undergoing rehabilitation after stroke.

METHODS

This retrospective cohort study included consecutive hospitalized post-stroke patients. Data on serum Hb level were extracted from medical records on tests performed within 24 h of admission. The main outcomes were discharge score for the skeletal muscle mass index (SMI) obtained through bioimpedance analysis and the corresponding change in SMI during hospitalization. Other outcomes were handgrip strength (HGS) at discharge and the alteration in HGS during hospitalization. Multivariate linear regression analyses were used to determine the association between Hb levels at admission and outcomes of interest, adjusted for potential confounders.

RESULTS

Data from 955 patients (mean age 73.2 years; 53.6% men) were included in the analysis. The median Hb level at admission was 13.3 [11.9, 14.5] g/dL. After fully adjusting for confounding factors, the baseline Hb level was significantly and positively associated with SMI at discharge (β = 0.046, P = 0.039) and with SMI gain (β = 0.010, P = 0.039). Further, the baseline Hb level was independently and positively associated with HGS at discharge (β = 0.058, P = 0.014) and with its change from baseline (β = 0.100, P = 0.014).

CONCLUSION

Diminished baseline Hb levels were demonstrated be correlated with compromised muscle health in patients after stroke. Evaluating anemia at the outset serves as a crucial prognostic indicator. Geriatr Gerontol Int 2024; 24: 305-311.

Appendicular Lean Mass, Grip Strength, and the Incidence of Dementia Among Older Adults in the Health ABC Study

BACKGROUND

Identification of novel risk factors for dementia in older adults could facilitate development of methods to identify patients most at risk and improve their cognitive outcomes. We aimed to determine whether lower appendicular lean mass (ALM), assessed by dual-energy x-ray absorptiometry (DXA), and lower grip strength are associated with a greater likelihood of incident dementia among older adults in the Health Aging and Body Composition Study (Health ABC).

METHODS

Health ABC data from 1997 to 2008 were analyzed (n = 2 704). Baseline ALM to body mass index (BMI) ratio (ALMBMI) was assessed by DXA. Baseline grip strength was assessed by hand-held dynamometry. Incident dementia diagnosis was defined as either (i) dementia-related hospitalization plus a Modified Mini-Mental State Examination (3MS) score of ≤ 90; or (ii) record of prescription for anti-dementia medication; or (iii) decline of at least 1.5 SDs on the 3MS score compared to baseline. Cox proportional hazard models estimated associations of ALMBMI and grip strength with incident dementia over follow-up with and without adjusting for covariates, stratified by sex.

RESULTS

Among older men, each standard deviation decrement in ALMBMI (adjusted hazard ratio [aHR]: 1.33; 95% confidence interval [CI]: 1.07, 1.65) or grip strength (aHR 1.22; 95% CI: 1.06, 1.41) was associated with increased likelihood of incident dementia.

CONCLUSIONS

Lower ALMBMI and grip strength may be important risk factors for the development of dementia among older men. How these factors may belong to a causal pathway of dementia must be elucidated in future work.

Alzheimer's disease and its associated risk of bone fractures: a narrative review

Background

Alzheimer's disease (AD) is a neurodegenerative disorder that is the major cause of dementia in the aged population. Recent researches indicate that patients with AD have a significantly increased fracture risk, but the pathological mechanisms are still unclear.

Objective

We systematically reviewed studies regarding bone fracture risk in AD to uncover links between the pathologies of osteoporosis and AD.

Methods

We searched the literature using the databases of PubMed, Web of Science, Embase and Cochrane Library. Studies were included if they evaluated bone fracture risk in AD patients and if they explored the pathogenesis and prevention of bone fractures in these patients.

Results

AD patients had a significantly higher risk of bone fractures than age-matched controls. Multiple factors contributed to the increased risk of bone fractures in AD patients, including the direct effects of amyloid pathology on bone cells, abnormal brain-bone interconnection, Wnt/β-catenin signalling deficits, reduced activity, high risk of falls and frailty, and chronic immune activity. Exercise, prevention of falls and fortified nutrition were beneficial for reducing the fracture risk in AD patients. However, the efficacy of anti-osteoporotic agents in preventing bone fractures should be further evaluated in AD patients as corresponding clinical studies are very scarce.

Conclusion

Alzheimer's disease patients have increased bone fracture risk and decreased bone mineral density owing to multiple factors. Assessment of anti-osteoporotic agents' efficacy in preventing bone fractures of AD patients is urgently needed.

Normal values for body composition in adults are better represented by continuous reference ranges dependent on age and BMI

BACKGROUND & AIMS

Reference values for body composition parameters like skeletal muscle mass index (SMI) depend on age and BMI. To ensure reference intervals reflect these changes, they have traditionally been separated into groups of young adults based on sex and BMI. However, this static stratification oversimplifies the dynamic and gradual changes of body composition with increasing age and BMI. The aim was therefore to provide continuous reference ranges for body composition parameters.

METHODS

Cross-sectional data of 1958 healthy men and women with an age between 18 and 97 years and a BMI between 17.1 und 45.6 kg/m² were obtained between 2011 and 2019. Multiple regression analyses stratified by sex with age, age² and BMI as independent variables were conducted to predict fat mass index (FMI), visceral adipose tissue (VAT), SMI, appendicular lean soft tissue index (ALSTI) and the ratio between extracellular to total body water (ECW/TBW).

RESULTS

The regression models explained between 61 (VAT in women and ALSTI in men) and 93% of the variance in the respective body composition parameters (FMI in women). Age had only a minor impact (2-16%) whereas BMI substantially increased the explained variance of reference models for FMI, VAT and ALSTI (total explained variance 61-93%). In SMI, age is a major determinant of the explained variance (36% in men and 38% in women) with BMI equally contributing to the explained variance (total explained variance 72% in men and 75% in women). For ECW/TBW-ratio, age nearly completely explained the variance (79% in men and 74% in women) whereas BMI added only 2-3% to the explained variance.

CONCLUSIONS

In conclusion, the derived continuous reference ranges are expected to improve body composition evaluation especially in very overweight and very old persons. Future studies applying these reference equations need to validate these assumptions. STUDY REGISTRATION, CLINICALTRIALS.GOV: NCT01368640, NCT01481285, NCT03779932, NCT04028648.