Search

Background: With aging, daily physical activity (PA) becomes less frequent and more fragmented. Accumulation patterns of daily PA-including transitions from active-to-sedentary behaviors-may provide important insights into functional status in older, less active populations.Methods: Participants of the Baltimore Longitudinal Study of Aging (n = 680, 50% male, aged 27-94 years) completed a clinical assessment and wore an Actiheart accelerometer. Transitions between active and sedentary states were modeled as a probability (Active-to-Sedentary Transition Probability [ASTP]) defined as the reciprocal of the average PA bout duration. Cross-sectional associations between ASTP and gait speed (m/s), fatigability (rating-of-perceived-exertion [RPE]), 400 m time (seconds), and expanded short physical performance battery score were modeled using linear and logistic regression, adjusted for chronic conditions. Further analyses explored the utility of ASTP over-and-above total daily PA.Results: In continuous models, each 0.10-unit higher ASTP was associated slower gait (β = -0.06 m/s, SE = 0.01), higher fatigability (β = 0.60 RPE, SE = 0.12), slower 400 m time (β = 16.31 s, SE = 2.70), and lower functioning (β = -0.13 expanded short physical performance battery score, SE = 0.03; p < .001). In categorical analyses, those in the highest tertile of ASTP were >2 times more likely to have high fatigability (rating of perceived exertion ≥10), slow 400 m time (>300 seconds) and reduced functional performance (expanded short physical performance battery score < 3.07) than those in the lowest tertile (p < .01). Further analyses demonstrated ASTP provided additional insight into functional outcomes beyond total daily PA.Conclusion: Fragmented daily PA-as measured by ASTP-is strongly linked with measures of health and functional status and may identify those at risk of high fatigability and reduced functional performance over and above traditional PA metrics. [ABSTRACT FROM AUTHOR]

Background: Although the "anti-aging hormone" klotho is associated with sarcopenia in mice, the relationship between klotho and muscle strength in older adults is not well known.Methods: Plasma klotho concentrations were measured in 2,734 older adults, aged 71-80 years, who participated in the Health, Aging and Body Composition Study, a prospective observational cohort study conducted in Memphis, TN and Pittsburgh, PA. Knee extension strength was measured using isokinetic dynamometry at baseline and follow-up 2 and 4 years later. Knee extension strength was normalized for weight.Results: At baseline, participants in the highest tertile of plasma klotho had higher knee extension strength (β = .72, standard error [SE] = .018, p < .0001) compared with those in the lowest tertile in a multivariable linear regression model adjusting for age, sex, race, smoking, study site, C-reactive protein, interleukin-6, and diabetes. Participants in the highest tertile of plasma klotho at baseline had less of a decline in knee strength over 4 years of follow-up (β = -.025, SE = .011, p = .02) compared with those in the lowest tertile in a multivariable linear regression model adjusting for the same covariates above.Conclusions: Plasma klotho concentrations were an independent predictor of changes in knee strength over time in older adults. Further studies are needed to identify the biological mechanisms by which circulating klotho could modify skeletal muscle strength. [ABSTRACT FROM AUTHOR]

Objectives To examine the association between multiple measures of visual impairment ( VI) and incident mobility limitations in older adults. Design Prospective observational cohort study. Setting Memphis, Tennessee, and Pittsburgh, Pennsylvania. Participants Health, Aging and Body Composition study participants aged 70 to 79 without mobility limitations at the Year 3 visit (N = 1,862). Measurements Vision was measured at the Year 3 visit, and VI was defined as distance visual acuity ( VA) worse than 20/40, contrast sensitivity ( CS) less than 1.55 log Contrast, and stereoacuity ( SA) greater than 85 arcsec. Incident persistent walking and stair climbing limitation was defined as two consecutive 6-month reports of any difficulty walking one-quarter of a mile or walking up 10 steps after 1, 3, and 5 years of follow-up. Results At Year 3 (baseline for these analyses), 7.4% had impaired VA, 27.2% had impaired CS, and 29.2% had impaired SA. At all follow-up times, the incidence of walking and stair climbing limitations was higher in participants with VA, CS, or SA impairment. After 5 years, impaired CS and SA were independently associated with greater risk of walking limitation (hazard ratio ( HR) CS = 1.3, 95% confidence interval ( CI) = 1.1-1.7; HRSA = 1.3, 95% CI = 1.1-1.6) and stair climbing limitation ( HRCS = 1.4, 95% CI = 1.1-1.8; HRSA = 1.3, 95% CI=1.1-1.7). Having impaired CS and SA was associated with greater risk of mobility limitations ( HRwalking limitations = 2.0, 95% CI = 1.6-2.5; HRstair limitation = 2.1, 95% CI = 1.6-2.8). Conclusion Multiple aspects of VI may contribute to mobility limitations in older adults. Addressing more than one component of vision may be needed to reduce the effect of vision impairment on functional decline. [ABSTRACT FROM AUTHOR]

Objectives To examine whether deficient B12 status or low serum B12 levels are associated with worse sensory and motor peripheral nerve function in older adults. Design Cross-sectional. Setting Health, Aging and Body Composition Study. Participants Two thousand two hundred and eighty-seven adults aged 72 to 83 (mean 76.5 ± 2.9; 51.4% female; 38.3% black). Measurements Low serum B12 was defined as serum B12 less than 260 pmol/ L, and deficient B12 status was defined as B12 less than 260 pmol/ L, methylmalonic acid ( MMA) greater than 271 nmol/ L, and MMA greater than 2-methylcitrate. Peripheral nerve function was assessed according to peroneal nerve conduction amplitude and velocity ( NCV) (motor), 1.4 g/10 g monofilament detection, average vibration threshold detection, and peripheral neuropathy symptoms (numbness, aching or burning pain, or both) (sensory). Results B12-deficient status was found in 7.0% of participants, and an additional 10.1% had low serum B12 levels. B12 deficient status was associated with greater insensitivity to light (1.4 g) touch (odds ratio = 1.50, 95% confidence interval = 1.06-2.13) and worse NCV (42.3 vs 43.5 m/s) (β = −1.16, P = .01) after multivariable adjustment for demographics, lifestyle factors, and health conditions. Associations were consistent for the alternative definition using low serum B12 only. No significant associations were found for deficient B12 status or the alternative low serum B12 definition and vibration detection, nerve conduction amplitude, or peripheral neuropathy symptoms. Conclusion Poor B12 (deficient B12 status and low serum B12) is associated with worse sensory and motor peripheral nerve function. Nerve function impairments may lead to physical function declines and disability in older adults, suggesting that prevention and treatment of low B12 levels may be important to evaluate. [ABSTRACT FROM AUTHOR]

Objective: The mechanisms that underlie the association between abdominal obesity and depression risk in older persons are not well known, but the "leptin hypothesis" of depression suggests that leptin resistance may be involved in mood regulation. We tested whether high circulatory concentration of leptin, alone and in combination with visceral adiposity, is associated with onset of depression in a sample of older persons., Method: Participants were 1,220 men and 1,282 women aged 70-79 years and enrolled in the Health, Aging, and Body Composition study. Serum concentration of leptin and abdominal visceral fat, ascertained by computed tomography, were assessed at baseline (April 1997-June 1998). Onset of depression, the primary outcome measure, was defined as a Center for Epidemiologic Studies-depression scale 10-item score ≥ 10 and/or new antidepressant medication use at any annual visit over a 5-year follow-up., Results: Higher leptin level was associated with the risk of depression onset in men with high levels of visceral fat (hazard ratio [HR] = 1.25; 95% CI, 1.06-1.46; P = .01) but not in those with normal visceral fat (HR = 0.98; 95% CI, 0.80-1.19; P = .80) (leptin-by-visceral fat, P = .04). No interaction between leptin and visceral fat was detected in the analysis focusing on women (P = .90)., Conclusions: In older men, high leptin level was associated with an increased onset of depressive symptoms, especially in the presence of abdominal obesity, suggesting that underlying leptin resistance may play a role in this link. Differences in visceral fat levels and metabolic consequences may explain the absence of this association in women. These findings suggest a potential biological link between depression, obesity, and their joint association with negative health outcomes., (© Copyright 2012 Physicians Postgraduate Press, Inc.)

Background: Health risks associated with subclinical hypothyroidism in older adults are unclear. Our objective was to compare the functional mobility of people aged 70 to 79 years by thyroid function categorized by thyrotropin (TSH) level as euthyroid (>or=0.4 to <4.5 mIU/L), mild subclinical hypothyroid (>or=4.5 to <7.0 mIU/L), or moderate subclinical hypothyroid (>or=7.0 to