Sex differences in the association between muscle quality, inflammatory markers, and cognitive decline

Abstract

Objective Aspects of frailty such as sarcopenia and dementia are associated with a proinflammatory state; however, little research has examined the concurrence of these pathologies. This study examined sex-specific differences in the relationship between low muscle quality and impaired cognitive functioning, while considering the role of inflammatory markers. Design The nationally representative sample was drawn from a cross-sectional study. Participants Four hundred forty-five females and four hundred twenty-two males over age 60 from the National Health and Nutrition Examination Survey for 2001-2002 were included. Measurements Muscle quality was calculated as isokinetic strength per unit muscle mass. Skeletal muscle mass of the legs was measured using dual energy x-ray absorptiometry and isokinetic strength of the knee extensors was estimated using a Kin-Com dynamometer. Participants were assessed for cognitive functioning using the Wechsler Adult intelligence Scale, Third Edition (WAIS-III) Digit Symbol - Coding module. High sensitivity C-reactive protein (CRP) assays were performed on blood samples using a Behring Nephelometer to estimate levels of inflammation. Sex stratified ordinary least squares regression models were utilized to estimate the relationship between muscle quality and cognitive functioning, while examining CrP as a possible mechanism and controlling for potential confounds. Results In the first model a statistically significant positive relationship was found between cognitive functioning and muscle quality for both sex groups. In the second model, CRP was found to have a statistically significant negative association with cognitive functioning for females but not males. Furthermore, the inclusion of CRP in the second model significantly reduced the predictive power of muscle quality for females, as compared to model 1. Conclusion Measures of sarcopenia are associated with lower cognitive functioning in older adults, and for females, this association may be partly due to systemic inflammation. Further research is need to examine the relationship between these frailty-related pathologies, which have substantial health and economic implications.

Sex differences in frailty: A systematic review and meta-analysis

“…Importantly, self-reported disability seems to correlate well with performance, with females testing as more disabled than males on performance measures (Merrill et al, 1997). Sex differences in biological factors, such as inflammatory cytokines, sarcopenia, abdominal adiposity and cognitive impairment, are emerging in the literature and probably underpin sex differences in co-morbidity and disability (Canon and Crimmins, 2011;Hubbard et al, 2010).…”

Obesity and sex interact in the regulation of Alzheimer's disease

“…Some research suggests that this relationship is stronger in women. For example, high inflammation was associated with poor cognitive performance in women but not men (Canon and Crimmins, 2011; Trollor et al, 2011). Similarly, another study found a correlation between high inflammation and mild cognitive impairment only in women (Trollor et al, 2010).…”

Gender Differences in C-Reactive Protein and Muscle Strengthening Activity

“…When stratified by gender, previous studies analyzing the distribution of elevated CRP (>3 mg/L), or the relationship between PA and CRP, have produced mixed results (4, 7, 17, 21, 23, 25). In a study of older adults conducted by Canon et al (7), analysis revealed that elevated levels of CRP mediated the relationship between cognitive function and muscle quality in females but not males.…”

“…Studies have also shown that protocols utilizing MSA are effective in decreasing circulating levels of CRP (13, 20, 32). However, there are few gender-stratified studies analyzing the distribution of elevated CRP (>3 mg/L), or the relationship between PA and CRP, and the limited current literature has revealed mixed results (4, 7, 17, 21, 23, 25). The purpose of this study is to examine the associations between self-reported MSA and CRP in adult participants of the National Health and Nutrition Examination Survey (NHANES) when stratified by gender.…”