Associations of fat mass and muscle function but not lean mass with cognitive impairment: The Yishun Study

Sarcopenic obesity and brain health: A critical appraisal of the current evidence

Sarcopenic obesity (SO) is a body composition phenotype derived from the simultaneous presence in the same individual of an increase in fat mass and a decrease in skeletal muscle mass and/or function. Several protocols for the diagnosis of SO have been proposed in the last two decades making prevalence and disease risk estimates of SO heterogeneous and challenging to interpret. Dementia is a complex neurological disorder that significantly impacts patients, carers and healthcare systems. The identification of risk factors for early cognitive impairment and dementia is key to mitigating the forecasted trends of a 2-fold increase in dementia case numbers over the next two decades worldwide. Excess adiposity and sarcopenia have both been independently associated with risk of cognitive impairment and dementia. Whether SO is associated with a greater risk of cognitive impairment and dementia is currently uncertain. This review critically appraises the current evidence on the association between SO with cognitive outcomes and dementia risk. It also discusses some of the putative biological mechanisms that may link the SO phenotype with alteration of brain functions.

Muscular strength, endothelial function and cognitive disorders: state of the art

In recent years, the ageing population has increasingly grown. This process carries a range of pathophysiological changes involving alterations in the skeletal muscle, vascular endothelium and brain function, becoming an important risk factor for developing cognitive disorders and cardiovascular diseases. With ageing, there is a decrease in muscle mass and muscle strength, and a relationship between muscle strength decrease and cognitive decline has been shown. Lower handgrip strength has been linked to memory impairment, lower global cognitive function, decreased attention and reduced visuospatial abilities in the elderly, but understanding of the underlying mechanisms that explain the link between altered skeletal muscle function and structure, endothelial dysfunction, and the role of endothelial dysfunction in the onset of cognitive disorders has been scarcely explored. This review aims to detail the cellular and molecular mechanisms by which the progressive changes associated with ageing can alter healthy skeletal muscle and endothelial function, creating an environment of oxidative stress, inflammation and mitochondrial dysfunction. These changes can lead to reduced muscle strength, and the secretion of detrimental endothelial factors, resulting in endothelial dysfunction, blood-brain barrier disruption, and damage to neurons and microglia, ultimately accelerating the onset of cognitive disorders in the elderly. In addition, we aimed to describe the mechanisms that potentially explain how preserving muscular function with resistance training could prevent brain function deterioration, including the production of different factors that allow an improved endothelial function, haemodynamic parameters and brain plasticity, ultimately delaying the onset of cognitive impairment and chronic diseases.

Understanding exogenous factors and biological mechanisms for cognitive frailty: A multidisciplinary scoping review

Cognitive frailty (CF) is the conjunction of cognitive impairment without dementia and physical frailty. While predictors of each element are well-researched, mechanisms of their co-occurrence have not been integrated, particularly in terms of relationships between social, psychological, and biological factors. This interdisciplinary scoping review set out to categorise a heterogenous multidisciplinary literature to identify potential pathways and mechanisms of CF, and research gaps. Studies were included if they used the definition of CF OR focused on conjunction of cognitive impairment and frailty (by any measure), AND excluded studies on specific disease populations, interventions, epidemiology or prediction of mortality. Searches used Web of Science, PubMed and Science Direct. Search terms included "cognitive frailty" OR (("cognitive decline" OR "cognitive impairment") AND (frail*)), with terms to elicit mechanisms, predictors, causes, pathways and risk factors. To ensure inclusion of animal and cell models, keywords such as "behavioural" or "cognitive decline" or "senescence", were added. 206 papers were included. Descriptive analysis provided high-level categorisation of determinants from social and environmental through psychological to biological. Patterns distinguishing CF from Alzheimer's disease were identified and social and psychological moderators and mediators of underlying biological and physiological changes and of trajectories of CF development were suggested as foci for further research.

Interactions between muscle volume and body mass index on brain structure in the UK Biobank

Background

Low skeletal muscle volume may increase dementia risk through mechanisms affecting brain structure. However, it is unclear whether this relationship exists outside of sarcopenia and/or varies by other factors. We aimed to study the interplay between skeletal muscle volume and factors, such as age, sex, and body mass index (BMI), in explaining brain structure at midlife in a cohort without sarcopenia.

Methods

We used abdominal and brain magnetic resonance imaging (MRI) data from a population-based cohort enrolled in the UK Biobank. The following measures were derived: thigh fat-free muscle volume (FFMV), total brain volume (TBV), gray matter volume (GMV), white matter volume (WMV), total hippocampal volume (THV), and white matter hyperintensity volume (WMHV). Participants below sex-based grip strength thresholds suggesting probable sarcopenia were excluded. Linear regression analysis was used to study the interaction or mediation effects of age, sex, and BMI on the associations between FFMV and brain volumes.

Results

Data were available for 20,353 participants (median age 64 years, 53% female). We found interactions between thigh FFMV, BMI, and age (all p < 0.05). Greater thigh FFMV was associated with better brain volumes in those aged <64 years with normal (TBV: β = 2.0 ml/L, p = 0.004; GMV: β = 0.8 ml/L, p = 0.04; WMV: β = 1.1 ml/L, p = 0.006; WMHV: β = -0.2 ml/L, p = 3.7 × 10-5) or low BMI (TBV: β = 21.2 ml/L, p = 0.003; WMV: β = 13.3 ml/L, p = 0.002, WMHV: β = -1.1 ml/L, p = 0.04).

Conclusion

Greater thigh muscle volume correlates with better brain volumes at midlife in people without sarcopenia, but this relationship weakens with greater age and BMI. Further study is required to investigate the underlying mechanisms to understand which components of body composition are potentially modifiable risk factors for dementia.

Body Composition, Sarcopenic Obesity, and Cognitive Function in Older Adults: Findings From the National Health and Nutrition Examination Survey (NHANES) 1999-2002 and 2011-2014

OBJECTIVE

Sarcopenic-obesity (SO) is characterized by the concomitant presence of low muscle mass and high adiposity. This study explores the association of body composition and SO phenotypes with cognitive function in older adults.

METHODS

Cross-sectional data in older adults (≥60 years) from NHANES 1999-2002 and 2011-2014 were used. In the 1999-2002 cohort, phenotypes were derived from body mass index (BMI) and dual-X-ray-absorptiometry, and cognition was assessed the by Digit-Symbol-Substitution-Test (DSST). In the 2011-2014 cohort, phenotypes were derived from BMI, waist-circumference (WC), and hand-grip-strength (HGS). Cognition was assessed using four tests: DSST, Animal Fluency, the Consortium-to-Establish-a-Registry-for-Alzheimer's-Disease-Delayed-Recall, and Word Learning. Mediation analysis was conducted to evaluate the contribution of inflammation (C-reactive-protein, CRP) and insulin resistance (Homeostatic-Model-Assessment-for-Insulin-Resistance, HOMA-IR) to the association between body composition and cognitive outcomes.

RESULTS

The SO phenotype had the lowest DSST mean scores (p < 0.05) and was associated with a significant risk of cognitive impairment [Odds Ratio (OR) = 1.9; 95%CI 1.0-3.7, p = 0.027] in the 1999-2002 cohort. A higher ratio of fat mass and fat free mass (FM/FFM) also showed a greater risk of cognitive impairment (OR = 2.0; 95%CI 1.3-3.1, p = 0.004). In the 2011-2014 cohort, the high WC-Low HGS group showed significantly lower scores on all four cognitive tests (p < 0.05) and a higher risk of cognitive impairment. CRP and HOMA-IR were significant partial mediators of the association between FM/FFM and DSST in the 1999-2002 cohort.

CONCLUSIONS

The SO phenotype was associated with a higher risk of cognitive impairment in older adults. Insulin resistance and inflammation may represent key mechanisms linking SO to the development of cognitive impairment.

Muscle density, but not size, is independently associated with cognitive health in older adults with hip fractures

Emerging evidence indicates a complex interplay between skeletal muscle and cognitive function. Despite the known differences between muscle quantity and quality, which can be measured via computed tomography (CT), the precise nature of their associations with cognitive performance remain underexplored. To investigate the links between muscle size and density and cognitive impairment (CI) in the older adults with hip fractures, we conducted a post hoc, cross-sectional analysis within a prospective cohort study on 679 patients with hip fractures over 65. Mini-Mental State Examination (MMSE) and routine hip CT imaging were utilized to assess cognition function and muscle characteristics in older adults with hip fractures. The CT scans provided data on cross-sectional area and attenuation for the gluteus maximus (G.MaxM) and the combined gluteus medius and minimus (G.Med/MinM). Participants were categorized into CI and non-CI groups based on education levels and MMSE scores. Multivariate logistic regressions, propensity score (PS) methods, and subgroup analysis were employed to analyze associations and validate findings. This study included 123 participants (81.6 ± 6.8 years, 74% female) with CI and 556 participants (78.5 ± 7.7 years, 72% female) without. Compared to the non-CI group, muscle parameters, especially density, were significantly lower in the CI group. Specifically, G.Med/Min muscle density, but not size was robustly associated with CI (odds ratio (OR) = 0.77, 95% confidence interval = 0.62-0.96, P = 0.02), independent of other medical situations. Sensitivity analysis corroborated that G.Med/Min muscle density was consistently lower in the CI group than the non-CI group, as evidenced in the PS matched (P = 0.024) and weighted cohort (P = 0.033). Enhanced muscle parameters, particularly muscle density in the G.Med/MinM muscle, correlate with a lower risk of CI. Muscle density demonstrates a stronger association with cognitive performance than muscle size, highlighting its potential as a key focus in future cognitive health research.

Deficits in force production during multifinger tasks demarcate cognitive dysfunction

BACKGROUND

The multifinger force deficit (MFFD) is the decline in force generated by each finger as the number of fingers contributing to an action is increased. It has been shown to associate with cognitive status.

AIMS

The aim was to establish whether a particularly challenging form of multifinger grip dynamometry, that provides minimal tactile feedback via cutaneous receptors and requires active compensation for reaction forces, will yield an MFFD that is more sensitive to cognitive status.

METHODS

Associations between measures of motor function, and cognitive status (Montreal Cognitive Assessment [MoCA]) and latent components of cognitive function (derived from 11 tests using principal component analysis), were estimated cross-sectionally using generalized partial rank correlations. The participants (n  =  62) were community dwelling, aged 65-87.

RESULTS

Approximately half the participants were unable to complete the dynamometry task successfully. Cognitive status demarcated individuals who could perform the task from those who could not. Among those who complied with the task requirements, the MFFD was negatively correlated with MoCA scores-those with the highest MoCA scores tended to exhibit the smallest deficits, and vice versa. There were corresponding associations with latent components of cognitive function.

DISCUSSION

The results support the view that neurodegenerative processes that are a feature of normal and pathological aging exert corresponding effects on expressions of motor coordination-in multifinger tasks, and cognitive sufficiency, due to their dependence on shared neural systems.

CONCLUSIONS

The outcomes add weight to the assertion that deficits in force production during multifinger tasks are sensitive to cognitive dysfunction.

Associations of sarcopenic obesity vs either sarcopenia or obesity alone with cognitive impairment risk in patients requiring maintenance hemodialysis

BACKGROUND

The association between sarcopenic obesity (SO) and cognitive impairment (CI) risk in patients requiring maintenance hemodialysis (MHD) is not known. In this study, we investigated the prevalence of SO in MHD patients. Furthermore, we would explore and compare the associations between SO, sarcopenia, and obesity with CI risk in this population.

METHODS

A multicenter, cross-sectional study was conducted. Data from 2743 adult MHD patients were recorded. SO was defined as the co-occurrence of sarcopenia and obesity. Cognitive function was assessed with the Mini-Mental State Examination (MMSE). Multiple logistic regression models, stratified analyses, and interactive analyses were conducted.

RESULTS

21.58% of the participants met the criteria for SO. The overall prevalence of CI was 23.3% in our study. Participants in the SO group had the highest CI prevalence (34.6%). The association between SO and CI was weakened but remained statistically significant after adjusting for age, sex, and educational status (odds ratio, 1.47; 95% CI, 1.11-1.96). However, associations between sarcopenia, obesity, and CI disappeared after adjusting for these variables. The additional adjustment did not attenuate the significant association between SO and CI. Subgroup analyses and interactive analyses showed that the associations were similar across subgroups (P > 0.05 for interaction for all).

CONCLUSIONS

SO and CI are highly prevalent in MHD patients. Participants with SO are at significantly higher risk of CI than those with sarcopenia or obesity alone. Furthermore, this association is consistent across different subgroups.

Prevalence of nutrition disorders and nutrition-related conditions in older patients with Alzheimer's disease

BACKGROUNDS

Alzheimer's disease is frequently encountered with nutrition-related conditions such as malnutrition, sarcopenia, frailty, overnutrition, and micronutrient abnormalities in older patients. In this study, we aimed to evaluate the prevalence of nutrition disorders and nutrition-related conditions in the same patient group.

METHODS

A total of 253 older patients with Alzheimer's disease underwent comprehensive geriatric assessment, which included nutrition-related disorders, malnutrition via the Mini Nutritional Assessment-Short Form (MNA-SF), frailty via the Clinical Frailty Scale (CFS), and sarcopenia was diagnosed according to European Working Group on Sarcopenia in Older People-2 criteria.

RESULTS

The patients' mean age was 79.8 ± 6.5 years, and 58.1% were women. In our patients, 64.8% had malnutrition or were at risk of malnutrition; 38.3% had sarcopenia; 19.8% were prefrail; and 80.2% were frail. Malnutrition, frailty, and sarcopenia prevalence increased as the Alzheimer's disease stage progressed. Malnutrition was found to be significantly related with frailty scores via CFS (odds ratio [OR], 1.397; P = 0.0049) and muscle mass via fat-free mass index (FFMI) (OR, 0.793; P = 0.001). In logistic regression analysis, age, MNA-SF, and CFS were included in the model to detect the independent correlates of probable and confirmed sarcopenia. CFS was independently associated with probable and confirmed sarcopenia (OR, 1.822; P = 0.013; OR, 2.671; P = 0.001, respectively). Frailty was similarly related with FFMI (OR, 0.836; P = 0.031). Obesity was independently related with FFMI (OR, 0.688; P < 0.001).

CONCLUSION

In conclusion, nutrition disorders and nutrition-related conditions can present concurrently in patients with all stages of Alzheimer's disease; therefore, these frequent problems should be screened and diagnosed accordingly.

A narrative review on the impact of sarcopenic obesity and its psychological consequence in quality of life

BACKGROUND AND AIM

Sarcopenia is a multifactorial metabolic-mediated complication that affects most of the geriatric population physically and mentally. In this study, we intended to study the association between sarcopenia and psychologically related symptoms. Primary objective of the study is to explore the interplay between sarcopenic obesity, psychological consequences and Quality of life in the affected population. The secondary objective is to discuss the diagnostic, treatment approaches and also the role of clinical pharmacist.

METHOD

The psychology-related complication and sarcopenia association was enumerated in this study based on previous clinical research findings.

RESULT

The clinical evidence shows a strong correlation between sarcopenia and Mental health and its health consequences and reflection on the quality of life.

CONCLUSION

Sarcopenia induced mental disturbance has been affirmed in many studies. We believe effective right pharmacological therapy and non-pharmacological therapies with respective lifestyle modification advice could be potential vital factors that can reduce further complications in geriatric populations.

Sarcopenic obesity using the ESPEN and EASO consensus statement criteria of 2022 - Results from the German KORA-Age study

OBJECTIVE

The recent consensus statement of ESPEN and EASO recommends reviewing existing datasets to assess the prevalence of sarcopenic obesity based on the new definition and diagnostic criteria. Therefore, this study aimed to determine the prevalence of sarcopenic obesity in a population-based study and to assess the association of this new definition with clinical traits.

METHODS

The KORA (Cooperative Health Research in the Region of Augsburg)-Age baseline examination (2008/2009) comprised 1079 participants aged 65 years and older from southern Germany. Sarcopenic obesity was defined in 998 participants (mean age 75.6 years, 498 women) with complete data according to the 2022 ESPEN and EASO algorithm, which includes reduced handgrip strength, reduced skeletal muscle mass per weight, and elevated fat mass. Body composition was measured using bioelectrical impedance analysis. Associations between sarcopenic obesity and physical activity, disability, multimorbidity, and polypharmacy were assessed using logistic regression analysis.

RESULTS

The overall prevalence of sarcopenic obesity was 4.5 % (5.0 % in men, 4.0 % in women). Sarcopenic obesity was associated with disability (2.87 [CI 1.84-4.48]), multimorbidity (≥ 2 comorbidities; 2.59 [CI 1.23-5.46]), polypharmacy (≥ 5 drugs; 1.96 [CI 1.05-3.63]), cognitive impairment (3.03 [CI 1.51-6.06]) and arthritis (2.66 [CI 1.39-5.07]) after adjusting for age, sex and marital status.

CONCLUSION

Sarcopenic obesity is prevalent in the older German population and is associated with several clinical traits. Future longitudinal studies are needed to further elucidate whether the observed associations could be causal.

Grip Strength and Sarcopenia Predict 2-Year Cognitive Impairment in Community-Dwelling Older Adults

OBJECTIVES

Using the Asian Working Group for Sarcopenia (AWGS2019) and the European Working Group on Sarcopenia in Older People (EWGSOP2) criteria, this study examined associations of sarcopenia and its components with specific domains of cognitive impairment over time.

DESIGN

A prospective cohort study with a 2-year follow-up.

SETTING AND PARTICIPANTS

This study is part of the Taiwan Initiatives for Geriatric Epidemiological Research (TIGER), which recruited participants aged 65 years old who attended the senior health checkup program at National Taiwan University Hospital (NTUH).

METHODS

Grip strength was measured using a handgrip dynamometer. Walking speed (m/s) was measured as the time required to walk 8 feet. Muscle mass was measured by performing a bioelectrical impedance analysis. Global cognition (assessed using the Taiwanese version of the Montreal Cognitive Assessment) and 4 cognitive domains (memory, executive function, verbal fluency, and attention) were assessed over time. Associations of sarcopenia and its components with cognitive impairment were evaluated after stratification by sex using generalized linear mixed models adjusted for essential covariates for cognitive impairment.

RESULTS

Compared with robust women, those with severe sarcopenia were more likely to have a global cognitive impairment over time (β = -0.87, P = .03 based on AWGS2019 criteria and β = -1.07, P = .02 based on the EWGSOP2 criteria). Among men, low grip strength was associated with poor scores on measures of global cognition (β = -0.80, P = .03), executive function (β = -0.35, P = .001), verbal fluency (β = -0.31, P = .02), and attention (β = -0.34, P = .008) over time.

CONCLUSIONS AND IMPLICATIONS

Severe sarcopenia predicted global and specific domains of cognitive impairment in older adults. Poor grip strength predicted cognitive impairment in men but not in women. A screen for sarcopenia severity and low muscle strength may be used to identify the risk of cognitive impairment.

Does the regulation of skeletal muscle influence cognitive function? A scoping review of pre-clinical evidence

Background

Cognitive impairment is a major challenge for elderlies, as it can progress in a rapid manner and effective treatments are limited. Sarcopenic elderlies have a higher risk of dementia. This scoping review aims to reveal whether muscle is a mediator of cognitive function from pre-clinical evidence.

Methods

PubMed, Embase, and Web of Science were searched to Feb 2nd, 2022, using the keywords (muscle) AND (cognition OR dementia OR Alzheimer) AND (mouse OR rat OR animal). The PRISMA guideline was used in this study.

Results

A total of 17 pre-clinical studies were selected from 7638 studies. 4 studies reported that muscle atrophy and injury harmed memory, functional factors, and neurons in the brain for rodents with or without Alzheimer's disease (AD). 3 studies observed exercise induced muscle to secrete factors, including lactate, fibronectin type III domain-containing protein 5 (FNDC5), and cathepsin B, which plays essential roles in the elevation of cognitive functions and brain-derived neurotrophic factor (BDNF) levels. Muscle-targeted treatments including electrical stimulation and intramuscular injections had effective remote effects on the hippocampus. 6 studies showed that muscle-specific overexpression of scFv59 and Neprilysin, or myostatin knockdown alleviated AD symptoms. 1 study showed that muscle insulin resistance also led to deficient hippocampal neurogenesis in MKR mice.

Conclusions

The skeletal muscle is involved in the mediation of cognitive function. The evidence was established by the response in the brain (altered number of neurons, functional factors, and other AD pathological characteristics) with muscle atrophy or injury, muscle secretory factors, and muscle-targeted treatments.

The translational potential of this paper

This study summarizes the current evidence in how muscle affects cognition in molecular levels, which supports muscle-specific treatments as potential clinical strategies to prevent cognitive dysfunction.

Musculoskeletal Deficits and Cognitive Impairment: Epidemiological Evidence and Biological Mechanisms

PURPOSE OF REVIEW

Cognitive impairment is associated with obesity, sarcopenia, and osteoporosis. However, no critical appraisal of the literature on the relationship between musculoskeletal deficits and cognitive impairment, focusing on the epidemiological evidence and biological mechanisms, has been published to date. Herein, we critically evaluate the literature published over the past 3 years, emphasizing interesting and important new findings, and provide an outline of future directions that will improve our understanding of the connections between the brain and the musculoskeletal system.

RECENT FINDINGS

Recent literature suggests that musculoskeletal deficits and cognitive impairment share pathophysiological pathways and risk factors. Cytokines and hormones affect both the brain and the musculoskeletal system; yet, lack of unified definitions and standards makes it difficult to compare studies. Interventions designed to improve musculoskeletal health are plausible means of preventing or slowing cognitive impairment. We highlight several musculoskeletal health interventions that show potential in this regard.

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.