Age-associated declines in muscle mass, strength, power, and physical performance: impact on fear of falling and quality of life.

UNLABELLED: This 3-year longitudinal study among older adults showed that declining muscle mass, strength, power, and physical performance are independent contributing factors to increased fear of falling, while declines of muscle mass and physical performance contribute to deterioration of quality of life. Our findings reinforce the importance of preserving muscle health with advancing age. INTRODUCTION: The age-associated loss of skeletal muscle quantity and function are critical determinants of independent physical functioning in later life. Longitudinal studies investigating how decrements in muscle components of sarcopenia impact fear of falling (FoF) and quality of life (QoL) in older adults are lacking. METHODS: Twenty-six healthy older subjects (age, 74.1 ± 3.7; Short Physical Performance Battery (SPPB) score ≥10) and 22 mobility-limited older subjects (age, 77.2 ± 4.4; SPPB score ≤9) underwent evaluations of lower extremity muscle size and composition by computed tomography, strength and power, and physical performance at baseline and after 3-year follow-up. The Falls Efficacy Scale (FES) and Short Form-36 questionnaire (SF-36) were also administered at both timepoints to assess FoF and QoL, respectively. RESULTS: At 3-year follow-up, muscle cross-sectional area (CSA) (p < 0.013) and power decreased (p < 0.001), while intermuscular fat infiltration increased (p < 0.001). These decrements were accompanied with a longer time to complete 400 m by 22 ± 46 s (p < 0.002). Using linear mixed-effects regression models, declines of muscle CSA, strength and power, and SPPB score were associated with increased FES score (p < 0.05 for each model). Reduced physical component summary score of SF-36 over follow-up was independently associated with decreased SPPB score (p < 0.020), muscle CSA (p < 0.046), and increased 400 m walk time (p < 0.003). CONCLUSIONS: In older adults with and without mobility limitations, declining muscle mass, strength, power, and physical performance contribute independently to increase FoF, while declines of muscle mass and physical performance contribute to deterioration of QoL. These findings provide further rationale for developing interventions to improve aging muscle health.

Abdominal obesity is associated with arterial stiffness in middle-aged adults.

BACKGROUND AND AIMS: The relation between adiposity and arterial stiffness remains controversial. We determined whether abdominal and visceral adipose tissue may be a better predictor of arterial stiffness than general obesity in middle-aged adults. METHODS AND RESULTS: A total of 146 participants (76 men, 70 women; 50 years) were studied. The automatic vascular screening device (Omron VP-1000plus) was used to measure blood pressure simultaneously in the arms and ankles and to determine arterial stiffness by pulse wave velocity (PWV). Using multiple linear regressions, the relations between indicators of obesity and arterial stiffness were examined after adjustment for confounders. Both carotid-femoral PWV and brachial-ankle PWV were significantly associated with BMI (both P < 0.05) but not with body fat percentage. Measures of abdominal obesity, including waist circumference and visceral fat mass (via DXA), were strongly associated with PWV and remained positively associated with arterial stiffness after adjustment for age and gender. Cardiovascular fitness as assessed by maximal oxygen consumption was related to body fat percentage but not with visceral fat. More favorable cardiovascular health profile was associated with both lower visceral fat mass and PWV (both P < 0.001). CONCLUSION: Abdominal obesity and visceral fat are associated with large artery stiffness. These findings support the importance of adiposity measures as a risk factor for arterial stiffening in middle-aged adults.

Central adiposity and the functional magnetic resonance imaging response to cognitive challenge.

BACKGROUND: Excessive adipose tissue, particularly with a centralized distribution, propagates hormonal and metabolic disturbance. The detrimental effects of adiposity may extend beyond the periphery and target the central nervous system, increasing vulnerability to cognitive decline. The aim of the current study was to determine how central adiposity impacts the brain at midlife by examining the blood oxygen level-dependent (BOLD) response to a challenging cognitive task. METHODS: Seventy-three adults, aged 40-60 years, completed a 2-back verbal working memory task during functional magnetic resonance imaging. Central adiposity was assessed with waist circumference. The association between waist circumference and task-related activation in a priori regions of interest was modeled using bootstrapping regression models corrected for multiple-comparisons. RESULTS: Larger waist circumference was associated with diminished working-memory-related BOLD response in the right superior frontal gyrus (ß=-0.008, P=0.001, 95% CI: -0.012 to -0.004) and left middle frontal gyrus (ß=-0.009, P=0.002, 95% CI: -0.015 to -0.003), statistically adjusting for age, sex, systolic blood pressure and total cholesterol. Reduced task-related activation in the right superior frontal gyrus (r=-0.369, P=0.002) and left middle frontal gyrus (r=-0.266, P=0.025) were related to slower reaction time on the task, controlling for age and education. CONCLUSIONS: Larger waist circumference predicted alterations in the BOLD response that coupled with decrements in task performance. While future studies are necessary, the results suggest that similar to its role in the periphery, central adiposity may be a robust predictor of metabolic and hormonal alterations that impinge upon central nervous system functioning.

Tuberculosis surveillance using a hidden markov model.

BACKGROUND: Routinely collected data from tuberculosis surveillance system can be used to investigate and monitor the irregularities and abrupt changes of the disease incidence. We aimed at using a Hidden Markov Model in order to detect the abnormal states of pulmonary tuberculosis in Iran. METHODS: Data for this study were the weekly number of newly diagnosed cases with sputum smear-positive pulmonary tuberculosis reported between April 2005 and March 2011 throughout Iran. In order to detect the unusual states of the disease, two Hidden Markov Models were applied to the data with and without seasonal trends as baselines. Consequently, the best model was selected and compared with the results of Serfling epidemic threshold which is typically used in the surveillance of infectious diseases. RESULTS: Both adjusted R-squared and Bayesian Information Criterion (BIC) reflected better goodness-of-fit for the model with seasonal trends (0.72 and -1336.66, respectively) than the model without seasonality (0.56 and -1386.75). Moreover, according to the Serfling epidemic threshold, higher values of sensitivity and specificity suggest a higher validity for the seasonal model (0.87 and 0.94, respectively) than model without seasonality (0.73 and 0.68, respectively). CONCLUSION: A two-state Hidden Markov Model along with a seasonal trend as a function of the model parameters provides an effective warning system for the surveillance of tuberculosis.