Evaluation of the Quantitative Myasthenia Gravis Score and Grip Strength in Chinese Patients With Myasthenia Gravis: An Observational Study

Introduction: The quantitative myasthenia gravis score is a commonly used scale for evaluating muscle weakness associated with myasthenia gravis (MG). It has been reported that some items used in the scale have low discriminative properties. However, there has been no research investigating the applicability of the quantitative MG score (QMGS) in Chinese patients with MG. In addition, the scoring method and ranges of grip strength items in QMGS need to be further evaluated.Methods: This study included 106 Chinese patients with MG, enrolled between September 2020 and February 2021, who were evaluated using the QMGS. Each item in the QMGS was analyzed for distribution. Three methods of evaluating grip strength, grip strength decrement, maximum grip strength, and relative grip strength, were compared. The correlation between the QMG total score minus grip strength score, and three evaluating methods, was analyzed.Results: The grip strength, swallowing, speech, diplopia, ptosis, and facial muscles items showed a clustered distribution. Most patients (94%) presented their maximum grip strength in the first four grip strength measurements. The QMG total score minus the grip strength score had a weak correlation with grip strength decrement (R grip r = 0.276; L grip r = 0.353, both p < 0.05) and moderate correlations with maximum grip strength (R grip r = −0.508; L grip r = −0.507; both p < 0.001) and relative grip strength (R grip r = −0.494; L grip r = −0.497, both p < 0.001).Conclusions: This study suggested that partial items in the QMGS have low discriminative properties for Chinese populations and the maximum grip strength value is the better method to evaluate grip strength compared to the other two scoring methods. Based on the quartiles of maximum grip strength, we propose new scoring ranges for the grip strength items.

Grip strength from midlife as an indicator of later-life brain health and cognition: evidence from a British birth cohort

Background Grip strength is an indicator of physical function with potential predictive value for health in ageing populations. We assessed whether trends in grip strength from midlife predicted later-life brain health and cognition. Methods 446 participants in an ongoing British birth cohort study, the National Survey of Health and Development (NSHD), had their maximum grip strength measured at ages 53, 60–64, and 69, and subsequently underwent neuroimaging as part of a neuroscience sub-study, referred to as “Insight 46”, at age 69–71. A group-based trajectory model identified latent groups of individuals in the whole NSHD cohort with below- or above-average grip strength over time, plus a reference group. Group assignment, plus standardised grip strength levels and change from midlife were each related to measures of whole-brain volume (WBV) and white matter hyperintensity volume (WMHV), plus several cognitive tests. Models were adjusted for sex, body size, head size (where appropriate), sociodemographics, and behavioural and vascular risk factors. Results Lower grip strength from midlife was associated with smaller WBV and lower matrix reasoning scores at age 69–71, with findings consistent between analysis of individual time points and analysis of trajectory groups. There was little evidence of an association between grip strength and other cognitive test scores. Although greater declines in grip strength showed a weak association with higher WMHV at age 69–71, trends in the opposite direction were seen at individual time points with higher grip strength at ages 60–64, and 69 associated with higher WMHV. Conclusions This study provides preliminary evidence that maximum grip strength may have value in predicting brain health. Future work should assess to what extent age-related declines in grip strength from midlife reflect concurrent changes in brain structure.

488 GRIP STRENGTH FROM MIDLIFE AS AN INDICATOR OF LATER-LIFE COGNITION AND BRAIN HEALTH: EVIDENCE FROM A BRITISH BIRTH COHORT

Introduction Grip strength is an objective measure of physical function with potential predictive value for health in ageing populations. We aimed to assess whether levels and changes in grip strength from midlife predicted later-life brain health and cognition. Methods 446 participants in an ongoing British birth cohort study, the MRC National Survey of Health and Development (NSHD), had their maximum grip strength measured at ages 53, 60–64, and 69, and underwent neuroimaging as part of its neuroscience sub-study, Insight 46, at 69–71. A group-based trajectory model identified latent groups of individuals in the whole NSHD cohort with below- and above-average grip strength over time, plus a reference group. Trajectory group membership, plus standardised grip strength levels and change from age 53, were each related to MRI-derived measures of whole-brain volume (WBV) and white-matter hyperintensity volume (WMHV), plus several cognitive tests. Models were adjusted for sex, body size, head size (where appropriate), sociodemographics, and behavioural and vascular risk factors. Results Consistently below-average grip strength from midlife was associated with lower WBV and non-verbal reasoning ability at age 69–71 (e.g. low group WBV vs. reference group β = −13.38 cm^3; 95% CI = (−24.12 cm^3, −2.64 cm^3); p = 0.015). There was some accompanying evidence that above-average maximum grip strength showed a positive association with WBV, which was more pronounced in female participants (high group female WBV vs. reference group β = 18.30 cm^3; 95% CI = (1.34 cm^3, 35.29 cm^3); p = 0.034). Steeper than average declines in grip strength between 53 and 69 were additionally weakly associated with an estimated 10% higher WMHV at age 69–71 (β = 1.10, 95% CI = (1.00, 1.22); p = 0.053). Conclusion This study provides preliminary evidence that tests of maximum grip strength may have value in predicting brain health. Future work should assess how these observed differences relate to later-life negative health outcomes, and whether changes in grip strength reflect concurrent changes in brain structure and connectivity.

Aging Increases Prosocial Motivation for Effort

Social cohesion relies on prosociality in increasingly aging populations. Helping other people requires effort, yet how willing people are to exert effort to benefit themselves and others, and whether such behaviors shift across the life span, is poorly understood. Using computational modeling, we tested the willingness of 95 younger adults (18–36 years old) and 92 older adults (55–84 years old) to put physical effort into self- and other-benefiting acts. Participants chose whether to work and exert force (30%–70% of maximum grip strength) for rewards (2–10 credits) accrued for themselves or, prosocially, for another. Younger adults were somewhat selfish, choosing to work more at higher effort levels for themselves, and exerted less force in prosocial work. Strikingly, compared with younger adults, older people were more willing to put in effort for others and exerted equal force for themselves and others. Increased prosociality in older people has important implications for human behavior and societal structure.

25 Sarcopenia, Long-Term Conditions, and Multimorbidity From Mid-Life to Later Life: Findings From 499,046 UK Biobank Participants

Introduction Sarcopenia, the loss of muscle strength and mass, predicts adverse outcomes and becomes common with age. There is recognition that sarcopenia may occur at younger ages in those with long-term conditions (LTCs) as well as those with multimorbidity (the presence of two or more LTCs), but their relationships have been little explored. Our aims were to describe the prevalence of sarcopenia in UK Biobank, a large sample of men and women aged 40–70 years, and to explore relationships with different categories of LTCs and multimorbidity. Methods We used data from 499,046 participants in the baseline of UK Biobank. Our main outcome was probable sarcopenia based on maximum grip strength below sex-specific cut-points. Participants’ LTCs were recorded during an interview and categorised against a hierarchy. We used logistic regression to examine the independent associations between each category of LTCs and probable sarcopenia, including adjustment for age, sex, and body mass index. We also examined the association with multimorbidity. Results Probable sarcopenia had an overall prevalence of 5.3% and increased with age. The categories with the strongest associations with probable sarcopenia were musculoskeletal/trauma (OR 2.17 [95% CI: 2.11, 2.23]), endocrine/diabetes (OR 1.49 [95% CI: 1.45, 1.55]), and neurological/psychiatric (OR 1.39 [95% CI: 1.34, 1.43]) LTCs. Almost half of the sample (44.5%) had multimorbidity and they were at nearly twice the odds of probable sarcopenia (OR 1.96 [95% CI: 1.91, 2.02]) compared to those without. Conclusions We have shown an overall prevalence of 5.3% of probable sarcopenia at ages 40–70 in UK Biobank. The risk of probable sarcopenia was higher in those with some categories of LTCs, suggesting that these groups may stand to benefit from assessment of sarcopenia, during mid-life as well as old age.

Evaluation of Effect of Handle Vibration Diesel-Fueled Single-Axle Tractor on Handgrip Strength of Operators

Background: The transmission of vibration from a single-axis tractor to the human body is determined by its dynamic response; this, in turn, depends on the physical characteristics of a person's hand, the contact area, the strength of the grip, the push force of the tractor, and the position. The purpose of this work was to measure and evaluate handgrip strength and fatigue resistance for operators of a 15 horsepower single-axle tractor before and after vibration exposure. Methods: Grip strength of dominant and non-dominant hands before and after 30 minutes of tilling operations was measured and recorded. The operators performed tilling tasks with the tractor in third gear, while the vibration levels were measured at the tractor handle along with the vertical, forward, and transverse directions. Results: The average operator grip strength was 33.6 ± 2.7 and 26.3 ± 3.3 kg and the average overall grip strength declined from 39.7 to 29.31 kg, although the average fatigue strength was 27.6 and 26.5 seconds for the dominant hand before and after vibration exposure. For the non-dominant hand, the mean grip strength measured was 28.7±2.9 and 23.1±1.9 kg and the maximum grip strength was 32.79 and 26.25, while fatigue was 29.76 and 22 seconds before and after tilling respectively.Conclusion: The average reduction in grip strength suggest considerable differences in grip strength for dominant and non-dominant hands of single axle tractor operators and shows that vibration transmitted from the single axle tractor handle has a major effect on the operators.

Periodontal Disease and Grip Strength among Older Adults

Objective: The aim of this research was to assess the association between periodontitis and grip strength among older American adults. Methods: Data from the National Health and Nutrition Examination Survey 2011/2012 and 2013/2014 were used. Oral health status and hand grip strength were clinically assessed. Three outcome variables were used: (1) handgrip strength <30 kg for men, <20 kg for women; (2) handgrip strength <26 kg for men, <16 kg for women; and (3) mean maximum grip strength. The main exposure was the case definition of periodontitis. Logistic and linear regression models were constructed for grip strength definitions and the mean grip strength, respectively, adjusting for covariates. Results: The study included 1953 participants. The mean age was 68.5 years, and 47.2% were males. The prevalence of low grip strength (<30 kg for men, <20 kg for women) was 7.4% in men and 13.6% in women. Periodontitis was significantly associated with grip strength (OR 1.53, 95% CI: 1.03, 2.27) in the unadjusted model. Periodontitis was also significantly associated with maximum grip strength (Coefficient 1.05, 95% CI −1.99, −0.09) in a model adjusted for age and gender. However, in all the fully adjusted models there was no statistically significant association between periodontitis and grip strength. Conclusion: Low grip strength appeared to be more common among persons with moderate/severe periodontitis. The observed association is probably attributed to older age and common risk factors for periodontitis and frailty.

Ageing increases prosocial motivation for effort

Social cohesion relies on prosociality in increasingly ageing populations. Helping others requires effort, yet how willing people are to exert effort to benefit ourselves and other people, and whether such behaviours shift across the lifespan, is poorly understood. Using computational modelling we tested the willingness to exert effort into self or other benefitting acts in younger (age 18-36) and older adults (55-84, total n=187). Participants chose whether to work and exert effort, (between 30-70% of maximum grip strength) for rewards (2-10 credits) accrued for themselves or prosocially for another. Younger adults were self-biased, choosing to work more at higher effort levels for themselves, but also superficial, exerting less force into prosocial work. Strikingly, compared to younger adults, older people were more willing to put in effort for others and exerted equal force for self and other. Increased prosociality in older people has important implications for human behaviour and societal structure.

HAND GRIP STRENGTH ASSESSMENT IN A HOME-DELIVERED MEAL PROGRAM: FEASIBILITY AND PRELIMINARY FINDINGS

Declining hand grip strength is associated with adverse health outcomes and is a relatively quick and easy-to-administer functional assessment; however, grip strength is not routinely assessed in home-delivered meal (HDM) programs. The purpose of this sub-study was to test if grip strength assessment is feasible and useful in a HDM population. Among HDM clients (n=258) who completed health assessments between 2016 and 2018, a voluntary convenience sample of 34 HDM clients (23 women, 11 men) participated in the grip strength assessment sub-study. Sub-study participants were younger (72.2+/-7.35 vs. 77.0+/-10.50 years), with no other significant differences compared to the full sample of HDM participants. The average maximum grip strength was 21.99+/-6.97 kg for the dominant hand; 16 clients were categorized as having normal, 6 intermediate, and 12 weak grip strength. Normative categories for grip strength vary by gender because men typically have higher grip strength measures than women. In this population, more men were categorized as having weak grip strength compared to women (X (2, 34) =11.44, p=.03). In men, hand grip strength tended to be lower in those who reported a fall in the previous 6 months compared to those who did not report a fall (20.8+/-7.01 vs 29.3+/-6.32, p=.079). The gender differences and 8 kg difference in grip strength relative to reported falls are clinically meaningful in this vulnerable population. Future research is needed with a larger sample of HDM clients to confirm these preliminary findings.