Ilse Reinders

Associations of BMI and adipose tissue area and density with incident mobility limitation and poor performance in older adults

BACKGROUND Obesity is a risk factor for disability, but risk of specific adipose depots is not completely understood. OBJECTIVE We investigated associations between mobility limitation, performance, and the following adipose measures: body mass index (BMI) and areas and densities of visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), and intermuscular adipose tissue (IMAT) in older adults. DESIGN This was a prospective population-based study of men (n = 1459) and women (n = 1552) initially aged 70-79 y and free from mobility limitation. BMI was determined from measured height and weight. Adipose tissue area and density in Hounsfield units were measured in the thigh and abdomen by using computed tomography. Mobility limitation was defined as 2 consecutive reports of difficulty walking one-quarter mile or climbing 10 steps during semiannual assessments over 13 y. Poor performance was defined as a gait speed <1 m/s after 9 y of follow-up (n = 1542). RESULTS In models adjusted for disability risk factors, BMI, and areas of VAT, abdominal SAT, and IMAT were positively associated with mobility limitation in men and women. In women, thigh SAT area was positively associated with mobility limitation risk, whereas VAT density was inversely associated. Associations were similar for poor performance. BMI and thigh IMAT area (independent of BMI) were particularly strong indicators of incident mobility limitation and poor performance. For example, in women, the HR (95% CI) and OR (95% CI) associated with an SD increment in BMI for mobility limitation and poor performance were 1.31 (1.21, 1.42) and 1.41 (1.13, 1.76), respectively. In men, the HR (95% CI) and OR (95% CI) associated with an SD increment in thigh IMAT for mobility limitation and poor performance were 1.37 (1.27, 1.47) and 1.54 (1.18, 2.02), respectively. CONCLUSIONS Even into old age, higher BMI is associated with mobility limitation and poor performance. The amount of adipose tissue in abdominal and thigh depots may also convey risk beyond BMI.

Plasma Phospholipid PUFAs Are Associated with Greater Muscle and Knee Extension Strength but Not with Changes in Muscle Parameters in Older Adults

BACKGROUND Muscle mass, intermuscular adipose tissue, and strength are important indicators of physical function. Dietary fatty acids (FAs) have been associated with muscle parameters such as larger size and higher strength, but large, population-based longitudinal data in older adults who are at risk of functional decline are lacking. OBJECTIVE The objective of this study was to investigate associations between plasma phospholipid polyunsaturated fatty acids (PUFAs) and measures of muscle size, intermuscular adipose tissue, and muscle strength cross-sectionally and after 5 y of follow-up. METHODS Data are from the Age, Gene/Environment Susceptibility-Reykjavik Study, a prospective cohort aged 66-96 y at baseline. The analytic sample included 836 participants with cross-sectional measures of muscle parameters and 459 participants with data on change in muscle parameters. PUFAs were assessed at study baseline through use of GC. Muscle parameters were assessed at baseline and after a median of 5.2 y. Muscle area and intermuscular adipose tissue were assessed with computed tomography. Maximal grip strength and knee extension strength were assessed with dynometers. Relative changes in muscle parameters (%) were calculated. Multivariate linear regression was performed to calculate unstandardized regression coefficients and P values for trends across tertiles of FAs are reported. RESULTS Higher concentrations of total PUFAs were cross-sectionally associated with larger muscle size (P-trend: 0.002) and with greater knee extension strength (P-trend: 0.038). Higher concentrations of arachidonic acid were associated with smaller muscle size (P-trend: 0.015). Greater linoleic acid was associated with less intermuscular adipose tissue (P-trend: 0.004), whereas eicosapentaenoic acid (20:5n-3) was positively associated (P-trend: 0.047). Longitudinal analyses showed positive associations for α-linolenic acid with increased knee extension strength (P-trend: 0.014). No other associations were observed. CONCLUSIONS These data illustrate the complex relation between plasma phospholipid PUFAs and muscle parameters; inconsistent cross-sectional relations with muscle size, intermuscular adipose tissue, and strength, and little evidence of a role in changes in muscle parameters.

Depressive Trajectories and Risk of Disability and Mortality in Older Adults: Longitudinal Findings From the Health, Aging, and Body Composition Study

BACKGROUND Depression and disability are closely linked. Less is known regarding clinical and subclinical depressive symptoms over time and risk of disability and mortality. METHODS Responses to the Center for Epidemiologic Studies Short Depression scale (CES-D10) were assessed over a 4-year period in men (n = 1032) and women (n = 1070) aged 70-79 years initially free from disability. Depressive symptom trajectories were defined with group-based models. Disability (2 consecutive reports of severe difficulty walking one-quarter mile or climbing 10 steps) and mortality were determined for 9 subsequent years. Hazard ratios (HRs) were estimated using Cox proportional hazards adjusted for covariates. RESULTS Three trajectories were identified: persistently nondepressed (54% of men, 54% of women, mean baseline CES-D10: 1.16 and 1.46), mildly depressed and increasing (40% of men, 38% of women, mean baseline CES-D10: 3.60 and 4.35), and depressed and increasing (6% of men, 8% of women, mean baseline CES-D10: 7.44 and 9.61). Disability and mortality rates per 1,000 person years were 41.4 and 60.3 in men and 45.8 and 41.9 in women. Relative to nondepressed, men in the mildly depressed (HR = 1.45, 95% confidence interval [CI] 1.11-1.89) and depressed trajectories (HR = 2.12, 95% CI 1.33-3.38) had increased disability; women in the depressed trajectory had increased disability (HR = 2.02, 95% CI 1.37-2.96). Men in the mildly depressed (HR = 1.24, 95% CI 1.01-1.52) and depressed trajectories (HR = 1.63, 95% CI 1.10-2.41) had elevated mortality risk; women exhibited no mortality risk. CONCLUSIONS Trajectories of depressive symptoms without recovery may predict disability and mortality in apparently healthy older populations, thus underscoring the importance of monitoring depressive symptoms in geriatric care.

Muscle Quality and Myosteatosis: Novel Associations With Mortality Risk: The Age, Gene/Environment Susceptibility (AGES)-Reykjavik Study.

Muscle composition may affect mortality risk, but prior studies have been limited to specific samples or less precise determination of muscle composition. We evaluated associations of thigh muscle composition, determined using computed tomography imaging, and knee extension strength with mortality risk among 4,824 participants aged 76.4 (standard deviation (SD), 5.5) years from the Age, Gene/Environment Susceptibility (AGES)-Reykjavik Study (2002-2006). Cox proportional hazards models were used to estimate hazard ratios. After 8.8 years of follow-up, there were 1,942 deaths. For men, each SD-increment increase in muscle lean area, muscle quality, and strength was associated with lower mortality risk, with decreases ranging between 11% and 22%. Each SD-increment increase in intermuscular adipose tissue and intramuscular adipose tissue was associated with higher mortality risk (hazard ratio (HR) = 1.13 (95% confidence interval (CI): 1.06, 1.22) and HR = 1.23 (95% CI: 1.15, 1.30), respectively). For women, each SD-increment increase in muscle lean area, muscle quality, and strength was associated with lower mortality risk, with decreases ranging between 12% and 19%. Greater intramuscular adipose tissue was associated with an 8% higher mortality risk (HR = 1.08, 95% CI: 1.01, 1.16). This study shows that muscle composition is associated with mortality risk. These results also show the importance of improving muscle strength and area and lowering muscle adipose tissue infiltration.

Adipose Tissue, Muscle, and Function: Potential Mediators of Associations Between Body Weight and Mortality in Older Adults With Type 2 Diabetes

OBJECTIVE Studies in type 2 diabetes report both increased mortality for normal weight and no evidence of an obesity paradox. We aimed to examine whether adipose tissue, muscle size, and physical function, which are known to vary by weight, mediate associations between BMI and mortality. RESEARCH DESIGN AND METHODS The AGES-Reykjavik cohort comprised participants aged 66–96 years with diabetes defined by fasting glucose, medications, or self-report. BMI was determined from measured height and weight and classified as normal (18.5–24.9 kg/m2, n = 117), overweight (25.0–29.9 kg/m2, n = 293, referent group) or obese (≥30.0 kg/m2, n = 227). Thigh muscle area and intermuscular, visceral, and subcutaneous adipose tissues were assessed with computed tomography. Function was assessed from gait speed and knee extensor strength. Hazard ratios (HRs) and 95% CIs were estimated by Cox proportional hazards regression adjusted for demographics and diabetes-related risk factors. RESULTS The median follow-up was 6.66 years, and there were 85, 59, and 44 deaths among normal weight, overweight, and obese participants, respectively. There was no mortality risk for obese participants and an increased risk among normal weight compared with overweight participants (HR 1.72 [95% CI 1.12–2.64]). Associations remained with adjustment for adipose tissues and knee extensor strength; however, mortality risk for normal weight was attenuated following adjustment for thigh muscle (HR 1.36 [95% CI 0.87–2.11]) and gait speed (HR 1.44 [95% CI 0.91–2.27]). Linear regression confirmed with bootstrapping indicated that thigh muscle size mediated 46% of the relationship between normal weight and mortality. CONCLUSIONS Normal weight participants had elevated mortality risk compared with overweight participants. This paradoxical association was mediated in part by muscle size.

Muscle Quality and Muscle Fat Infiltration in Relation to Incident Mobility Disability and Gait Speed Decline: the Age, Gene/Environment Susceptibility-Reykjavik Study

BACKGROUND Aging is associated with increased risk of reduced mobility. However, data on muscle components in relation to subjective and objective indicators of disability is limited. METHODS Data were from 2,725 participants (43% men) aged 74.8±4.7 years from the AGES-Reykjavik Study. At baseline, maximal isometric thigh strength (dynamometer chair), and midthigh muscle area and muscle fat infiltration were assessed with computed tomography. Usual 6 m gait speed and mobility disability were assessed at baseline and after 5.2±0.3 years. Incident mobility disability was defined as having much difficulty or unable to walk 500 m or climb-up 10 steps. A decrease of ≥0.1 m/s in gait speed was considered clinically relevant. RESULTS Greater strength and area were protective for mobility disability risk and gait speed decline. After adjustment for other muscle components, greater strength was independently associated with lower mobility disability risk in women odds ratios (OR) 0.78 (95% CI 0.62, 0.99), and lower decline in gait speed risk among both men OR 0.64 (0.54, 0.76), and women OR 0.72 (0.62, 0.82). Larger muscle area was independently associated with lower mobility disability risk in women OR 0.67 (0.52, 0.87) and lower decline in gait speed risk in men OR 0.74 (0.61, 0.91). CONCLUSIONS Greater muscle strength and area were independently associated with 15-30% decreased risk of mobility disability in women and gait speed decline in men. Among women, greater muscle strength was also associated with lower risk of gait speed decline. Interventions aimed at maintaining muscle strength and area in old age might delay functional decline.

Higher Plasma Phospholipid n–3 PUFAs, but Lower n–6 PUFAs, Are Associated with Lower Pulse Wave Velocity among Older Adults

BACKGROUND Higher intake of polyunsaturated fatty acids (PUFAs) and higher circulating PUFAs are associated with lower cardiovascular disease (CVD) risk. The positive influence of PUFAs might be via lowering arterial stiffness, resulting in a better CVD risk profile; however, studies investigating circulating PUFAs in relation to arterial stiffness in a general population are limited. OBJECTIVE We investigated the associations of plasma phospholipid n-3 (ω-3) and n-6 PUFAs and fish oil intake with arterial stiffness. METHODS We used data from a subgroup of the Age, Gene/Environment Susceptibility-Reykjavik (AGES-Reykjavik) Study (n = 501, 75.0 ± 4.96 y, 46% men), a population-based study of community-dwelling older adults. Plasma phospholipid PUFAs were measured by GC at baseline, and fish oil intake was assessed at 3 time points: early life (ages 14-19 y), midlife (ages 40-50 y), and late life (ages 66-96 y, AGES-Reykjavik baseline) with the use of a validated food-frequency questionnaire. Arterial stiffness was determined as carotid-femoral pulse wave velocity (cf-PWV) with the use of an electrocardiogram after a mean follow-up of 5.2 ± 0.3 y. Regression coefficients (95% CIs), adjusted for demographics, follow-up time, risk factors, cholesterol, triglycerides, and serum vitamin D, were calculated by linear regression per SD increment in PUFAs. RESULTS Plasma total n-3 PUFAs, eicosapentaenoic acid, and docosahexaenoic acid were associated with lower cf-PWV [β (95% CI): -0.036 (-0.064, -0.008); -0.031 (-0.059, -0.003); -0.036 (-0.064, -0.009), respectively]. In contrast, plasma total n-6 PUFAs and linoleic acid were associated with higher cf-PWV [0.035 (0.009, 0.061) and 0.034 (0.008, 0.059)]. Regular fish oil consumption at early-, mid-, and late-life was not associated with cf-PWV. CONCLUSIONS Our results show a positive association between plasma n-6 PUFAs and arterial stiffness, and suggest that higher concentrations of plasma long-chain n-3 PUFAs are associated with less arterial stiffness and therein may be one of the mechanisms underlying the association between plasma n-3 PUFAs and lower CVD risk.

Plasma phospholipid fatty acids and fish-oil consumption in relation to osteoporotic fracture risk in older adults: the Age, Gene/Environment Susceptibility Study

BACKGROUND Polyunsaturated fatty acids (PUFAs) may play a role in fracture, but studies have been largely confined to estimates of dietary intake. OBJECTIVE We aimed to examine associations between fatty acids measured in late life and fish-oil consumption in early life, midlife, and late life with osteoporotic fracture risk. DESIGN Osteoporotic fractures were determined from medical records over 5-9 y of follow-up in men and women aged 66-96 y. Data were analyzed from 1438 participants including 898 participants who were randomly selected from the Age, Gene/Environment Susceptibility Study, which is an observational study, and 540 participants with incident fracture. Plasma phospholipid fatty acids were assessed by using gas chromatography. Fish-oil consumption was assessed by using validated questionnaires as never (referent), less than daily, or daily. HRs and 95% CIs adjusted for age, education, height, weight, diabetes, physical activity, and medications were estimated by using Cox regression. RESULTS In men, the highest tertile of PUFAs, n-3 (ω-3), and eicosapentaenoic acid were associated with decreased fracture risk [HRs (95% CIs): 0.60 (95% CI: 0.41, 0.89), 0.66 (0.45, 0.95), and 0.59 (0.41, 0.86), respectively]. In women, PUFAs tended to be inversely associated with fracture risk (P-trend = 0.06), but tertiles 2 and 3 were not independently associated with risk. Tertile 2 of n-6 and arachidonic acid was associated with fracture risk in women [HRs (95% CIs): 1.43 (1.10, 1.85) and 1.42 (1.09, 1.85), respectively]. Daily fish-oil consumption in late life was associated with lower fracture risk in men (HR: 0.64; 95% CI: 0.45, 0.91). Daily fish-oil consumption in midlife was associated with lower fracture risk in women (HR: 0.75; 95% CI: 0.58, 0.98). CONCLUSIONS Greater PUFA concentrations may be associated with lower osteoporotic fracture risk in older adults, particularly in men. Critical time periods for n-3 fatty acid consumption may differ by sex.

Urinary Incontinence in Older Women: The Role of Body Composition and Muscle Strength: From the Health, Aging, and Body Composition Study.

To evaluate prospective relationships between body composition and muscle strength with predominantly stress urinary incontinence (SUI) and urgency urinary incontinence (UUI) in older women.

Body Mass Index Trajectories in Relation to Change in Lean Mass and Physical Function: The Health, Aging and Body Composition Study

To examine body mass index (BMI) trajectories with change in lean mass and physical function in old age.