MacArthur Studies Of Successful Aging Research Articles

Increases in Serum Non‐High‐Density Lipoprotein Cholesterol May Be Beneficial in Some High‐Functioning Older Adults: MacArthur Studies of Successful Aging

objectives: To examine the association between changes in serum non-high-density lipoprotein cholesterol (non-HDL-C) over a 2.5-year period and risk of adverse health outcomes in the following 4.5 years in high-functioning older adults. Prospective cohort, established in 1988, with a follow-up in 1991 and 1995. Population-based, community-dwelling men and women. A random sample (n=267) from the MacArthur cohort (N=1,189). The cohort represented the highest-functioning tertile of 4,030 screened candidates aged 70 to 79. Change in non-HDL-C between 1988 and 1991 was measured as a predictor of health outcomes between 1991 and 1995, including all-cause mortality, and among survivors, incident heart attack or stroke, development of new disability in basic activities of daily living, and decline in performance on the Short Portable Mental Status Questionnaire. More-positive change in non-HDL-C between 1988 and 1991 was associated with fewer adverse outcomes between 1991 and 1995. In individuals whose total cholesterol at baseline was in the middle two quartiles (195-244 mg/dL), each 10-mg/dL increase in the 1988-to-1991 change in non-HDL-C was associated with an adjusted mortality odds ratio (OR) of 0.67 (95% confidence interval (CI)=0.51-0.88). In individuals without cardiovascular disease at baseline, the adjusted OR for new physical disability was 0.79 (95% CI=0.65-0.95) and for cognitive decline was 0.81 (95% CI=0.67-0.98). Increases in cholesterol over time have beneficial associations in some older adults. The role of cholesterol changes in the health of older individuals needs further exploration.

Cumulative biological risk and socio-economic differences in mortality: MacArthur Studies of Successful Aging

Previous research has suggested that socio-economic status (SES) differences in mortality are only partially explained by differences in life-style, psychological and social factors. Seven year mortality data (1988–1995) from the MacArthur Study of Successful Aging, a longitudinal study of adults, aged 70–79, from New Haven, CT; East Boston, MA; and Durham, NC; were used to test the hypothesis that a cumulative measure of biological dysregulation (“allostatic load”), reflecting multiple regulatory systems, would serve as a further mediator of SES differences in mortality. Logistic regression analyses revealed that a cumulative index of biological risk explained 35.4% of the difference in mortality risk between those with higher versus lower SES (as measured by less than high school education versus high school or greater educational attainment). Importantly, the cumulative index provided independent explanatory power, over and above a measure of doctor-diagnosed disease, though the latter also contributed to education-related variation in mortality risks. The summary measure of biological risk also accounted for more variance than individual biological parameters, suggesting the potential value of a multi-systems view of biological pathways through which SES ultimately affects morbidity and mortality.

The associations between physical activity and inflammatory markers in high-functioning older persons: MacArthur Studies of Successful Aging.

To determine the relationships between recreational activity, house/yard work activity, work activity, and total physical activity and high levels of two peripheral blood markers of inflammation: interleukin-6 (IL-6) and C-reactive protein (CRP). Cross-sectional study. Three communities (Durham, NC; New Haven, CT; and East Boston, MA). Eight hundred seventy persons aged 70 to 79 who were in the top third of community-dwelling older persons with respect to physical and cognitive functioning. Blood levels of IL-6 and CRP and self-reported recreational activity, house/yard work activity, work activity, and total physical activity. The adjusted odds ratios (AORs) for individuals with high levels of recreational activity to have values in the top tertiles of IL-6 and CRP were 0.65 (95% confidence interval (CI) = 0.48-0.87) and 0.70 (95% CI = 0.51-0.95), respectively. The AORs for those with a high level of house/yard work activity to have values in the top tertile of IL-6 and CRP were 0.90 (95% CI = 0.67-1.20) and 0.70 (95% CI = 0.50-0.96), respectively. High levels of house/yard work and recreational activity were independently associated with lower risk of high CRP. The association between high levels of recreational activity and lower levels of the inflammatory markers IL-6 and CRP suggests a mechanism for its protective effect and supports interventions that increase physical activity in older persons. Such potential benefits of increased physical activity on inflammatory markers will need to be confirmed in clinical trials.

The role of APOE-epsilon4 in longitudinal cognitive decline: MacArthur Studies of Successful Aging.

While a genetic risk factor for late-onset AD, the effects of the epsilon4 allele of the APOE gene on cognitive functioning more generally remain unclear. To assess the role of the epsilon4 allele of the APOE gene in longitudinal cognitive decline. Multiple measures of cognitive function were assessed longitudinally in the MacArthur Successful Aging Study, a population-based cohort free of frank impairment at baseline. Subjects were 965 Caucasian and African American men and women from Durham NC, East Boston, MA, and New Haven, CT, aged 70 to 79 years, recruited in 1988 through 1989, who completed two follow-up evaluations, one at 3 years and another at 7 years. At the first follow-up, modest but significant declines in naming and spatial ability were associated with the APOE-epsilon4 genotype. By the second follow-up, more pronounced and significant associations were noted between the APOE-epsilon4 genotype and cognitive decline from six of the eight cognitive outcomes. After 7 years, APOE-epsilon4 allele carriers were twice as likely to have declined on a global cognitive score (odds ratio = 2.0; 95% CI: 1.1, 3.6) as noncarriers. APOE-epsilon4 is associated with cognitive decline among a high-functioning elderly cohort, with effects most pronounced after 7 years of follow-up. Hence, the epsilon4 allele either may function as a risk factor for cognitive impairment in normal aging across a broad spectrum of domains or may exert detectable effects early in a long prodromal AD trajectory.

Accounting for changes in social support among married older adults: Insights from the MacArthur Studies of Successful Aging.

Using longitudinal, community-based data from the MacArthur Studies of Successful Aging, the authors examined determinants of changes in social support receipt among 439 married older adults. In general, social support increased over time, especially for those with many preexisting social ties, but those experiencing more psychological distress and cognitive dysfunction reported more negative encounters with others. Gender affected social support receipt: Men received emotional support primarily from their spouses, whereas women drew more heavily on their friends and relatives and children for emotional support. Discussion centers on the importance of social support provision to those with the greatest needs.

Does inflammation or undernutrition explain the low cholesterol-mortality association in high-functioning older persons? MacArthur studies of successful aging.

To explore the effect of inflammation and undernutrition on the association between hypocholesterolemia and higher overall mortality in high-functioning older persons. Prospective cohort study. Three U.S. communities. A cohort of 870 participants from the MacArthur Studies of Successful Aging. Baseline information was obtained for serum levels of cholesterol, C-reactive protein, interleukin-6, and albumin; body mass index; prevalent medical conditions; health behaviors; and medications. Crude and multivariate logistic regression analyses were used to examine the association between serum total cholesterol levels and 7-year all-cause mortality, while adjusting for potential confounders. In univariate analysis, the risk ratio of low serum total cholesterol level (<169 mg/dL) for 7-year total mortality was 1.90 (95% confidence interval (CI) = 1.18-3.07). The multiple adjusted risk ratios were 1.82 (95% CI = 1.10-3.00) after controlling for markers of inflammation and nutrition and 1.39 (95% CI = 0.80-2.40) after adjustment for additional cardiovascular risk factors. Sex was an important confounding variable that contributed to the observed inverse association between low serum cholesterol and overall mortality in univariate analysis. Hypocholesterolemia is not an independent risk factor for increased overall mortality in high-functioning community-dwelling older men and women. The association between low total cholesterol and high mortality observed in crude analysis is mainly confounded by common cardiovascular risk factors, rather than underlying inflammation or undernutrition.

Homocysteine levels and decline in physical function: MacArthur studies of successful aging

Purpose To test whether elevated homocysteine levels are associated with an increased risk of decline in physical function in older persons. Methods We performed a prospective cohort study of 499 highly functioning men and women aged 70 to 79 years who were enrolled in the MacArthur Studies of Successful Aging. We measured total homocysteine levels and performance-based physical function at baseline; physical function measures were repeated an average of 28 months later. A summary measure of physical performance from tests of balance, gait, lower body strength and coordination, and manual dexterity was developed, and a change score was calculated as the difference in scores from 1988 to 1991. Results The mean (±SD) homocysteine level was 11.6 ± 4.3 μmol/L. With each SD increase in homocysteine, there was an increased risk of being in the worst quartile of decline in physical function (odds ratio = 1.5; 95% confidence interval: 1.2 to 1.9) in analyses that adjusted for age, sex, baseline physical performance, smoking status, vitamin B 12 levels, and incident stroke. Similar results were seen when change in physical performance was treated as a continuous variable. Conclusion Older persons with elevated plasma homocysteine levels are at an increased risk of decline in physical function.

Interleukin-6 and risk of cognitive decline: MacArthur studies of successful aging.

To investigate whether plasma interleukin-6 (IL-6) is cross-sectionally related to poorer cognitive function and whether a baseline plasma IL-6 measurement can predict risk for decline in cognitive function in longitudinal follow-up of a population-based sample of nondisabled elderly people. A prospective cohort study of 779 high-functioning men and women aged 70 to 79 from the MacArthur Study of Successful Aging was conducted. Regression modeling was used to investigate whether baseline IL-6 levels (classified by tertiles) were associated with initial cognitive function and whether IL-6 levels predicted subsequent declines in cognitive function from 1988 to 1991 (2.5-year follow-up) and from 1988 to 1995 (7-year follow-up). Subjects in the highest tertile for plasma IL-6 were marginally more likely to exhibit poorer baseline cognitive function (i.e., scores below the median), independent of demographic status, social status, health and health behaviors, and other physiologic variables (odds ratio [OR] = 1.46; 95% CI: 0.97, 2.20). At 2.5 years, those in both the second tertile of IL-6 (OR = 2.21; 95% CI: 1.44, 3.42) and the third tertile (OR = 2.03; 95% CI: 1.30, 3.19) were at increased risk of cognitive decline even after adjusting for all confounders. At 7 years of follow-up, only those in the highest IL-6 tertile were significantly more likely to exhibit declines in cognition (OR = 1.90; 95% CI: 1.14, 3.18) after adjustment for all confounders. The results suggest a relationship between elevated baseline plasma IL-6 and risk for subsequent decline in cognitive function. These findings are consistent with the hypothesized relationship between brain inflammation, as measured here by elevated plasma IL-6, and neuropathologic disorders.

Allostatic load as a predictor of functional decline: MacArthur studies of successful aging

Allostatic load has been proposed as a cumulative measure of dysregulation across multiple physiological systems, and has been postulated to impact health risks. In the allostatic load model, increased risk is hypothesized to result not only from large and clinically significant dysregulation in individual systems, but also from more modest dysregulation, if present in multiple systems. Our objective was to construct an allostatic load score by optimally combining several physiologic measurements, and to examine its association with future functional decline. We analyzed data from a 7-year longitudinal study of a community-based cohort, whose age at baseline was between 70 and 79 years. Canonical correlation analysis was used to study the association of 10 biological measurements representing allostatic load with declines in scores on five tests each of physical and cognitive function over two follow-up periods: 1998–1991 and 1991–1995. We used bootstrapping to evaluate the stability of the canonical correlation and canonical weights. The canonical correlation between allostatic load and the 20 decline scores was 0.43 (P = .03) and the [25th, 75th] percentile interval of its distribution over 200 bootstrapped subsamples of the cohort was [0.48, 0.53]. These findings were not substantially affected by adjusting for covariates and cardiovascular disease. We conclude that a summary measure of physiologic dysregulation, such as allostatic load, is an independent predictor of functional decline in elderly men and women.

Predicting cognitive impairment in high-functioning community-dwelling older persons: MacArthur Studies of Successful Aging.

To examine whether simple cognitive tests, when applied to cognitively intact older persons, are useful predictors of cognitive impairment 7 years later. Cohort study. Durham, North Carolina; East Boston, Massachusetts; and New Haven, Connecticut, areas that are part of the National Institute on Aging Established Populations for Epidemiological Studies of the Elderly. Participants, aged 70 to 79, from three community-based studies, who were in the top third of this age group, based on physical and cognitive functional status. New onset of cognitive impairment as defined by a score of less than 7 on the Short Portable Mental Status Questionnaire (SPMSQ) in 1995. At 7 years, 21.8% (149 of 684 subjects) scored lower than 7 on the SPMSQ. Using multivariate logistic regression, three baseline (1988) cognitive tests predicted impairment in 1995. These included two simple tests of delayed recall-the ability to remember up to six items from a short story and up to 18 words from recall of Boston Naming Test items. For each story item missed, the adjusted odds ratio (AOR) for cognitive impairment was 1.44 (95% confidence interval (CI) = 1.16-1.78, P <.001). For each missed item from the word list, the AOR was 1.20 (95% CI = 1.09-1.31, P <.001). The Delayed Recognition Span, which assesses nonverbal memory, also predicted cognitive impairment, albeit less strongly (odds ratio = 1.06 per each missed answer, 95% CI = 1.003-1.13, P =.04). This study identifies measures of delayed recall and recognition as significant early predictors of subsequent cognitive decline in high-functioning older persons. Future efforts to identify those at greatest risk of cognitive impairment may benefit by including these measures.

Risk and Protective Factors for Physical Functioning in Older Adults With and Without Chronic Conditions: MacArthur Studies of Successful Aging

Older age continues to be seen as a period of declining health and functioning. The inevitability of declines, however, may be exaggerated, including declines for those with chronic health conditions. Data from the MacArthur Study of Successful Aging were used to examine the impact of sociodemographic, health status, health behavior, and social and psychological factors on patterns of change in physical functioning over a 2.5-year interval for groups of older adults reporting prevalent hypertension, diabetes, cardiovascular disease, cancer, or fractures, and those reporting no chronic conditions at baseline. Findings from multiple regression analyses revealed a consistently protective effect of regular physical activity with respect to patterns of change in physical functioning in nearly all groups. For those with cardiovascular disease, greater emotional support was associated with higher baseline levels and less declines in functioning, whereas greater social conflict was associated with greater decline among those with hypertension or diabetes. For those with a history of cancer, instrumental self-efficacy beliefs were protective, whereas lower psychological symptomatology was associated with less risk of decline among those with a history of fracture. Social and psychological factors were unrelated to changes in functioning for those with no chronic conditions. These findings suggest that risks for decline in physical functioning are influenced by a number of potentially modifiable factors that could be targets for interventions to promote better functioning, even among older adults with various types of chronic conditions.

The relationship between cognitive and physical performance: MacArthur Studies of Successful Aging.

The relationship between change in cognitive and physical performance has yet to be fully understood. Because aging decreases the ability to learn new information while preserving more established knowledge, this article examines whether the association between change in cognitive and physical performance depends on the nature of the physical task. Data from the MacArthur Research Network on Successful Aging Community Study--a longitudinal three-site, cohort study of high-functioning, disability-free Americans aged 70 to 79 in 1988 (reinterviewed in 1991 and 1995)--are used for this investigation. We examine the association between change in cognitive performance and two categories of physical performance: novel/attentional demanding physical tasks (e.g., standing on a single leg) or routine physical tasks (e.g., walking at a normal pace). Change in physical performance (over 7 years) is regressed on change in cognitive performance (over the same period) controlling for baseline cognitive ability, demographic factors, health status, and behavioral characteristics. The findings suggest that declines in cognitive performance are associated with declines in both novel/attentional demanding and routine physical tasks. In addition to decline in cognition, gender, prevalent health conditions (e.g., cancer, high blood pressure, and the fracture of a hip), and smoking behavior are associated with decline in performance on some physical tasks. The findings suggest that the successful execution of physical tasks demands cognitive processes regardless of the nature of the task. Researchers using performance-based measures of physical functioning should pay particular attention to the cognitive capacities of their subjects and how these might influence their assessment.

Is Serum Uric Acid Level Associated with All‐Cause Mortality in High‐Functioning Older Persons: MacArthur Studies of Successful Aging?

To explore the effect of serum uric acid level on subsequent all-cause mortality in high-functioning community-dwelling older persons. It is controversial whether high serum uric acid level is a true independent risk factor for cardiovascular and total mortality or the association is due to other confounding variables. Furthermore, it remains unclear whether the predictive value of uric acid level on mortality observed in younger cohorts can be extended to older people. Prospective cohort study. A sample of community-dwelling older people. A cohort of 870 participants from the MacArthur Studies of Successful Aging. Baseline information was obtained for serum uric acid level, C-reactive protein (CRP), interleukin-6 (IL-6), prevalent medical conditions, and health behaviors. Crude and multivariate logistic regression analyses were used to examine the association between serum uric acid levels and 7-year all-cause mortality, while adjusting for potential confounders. In men, the multiply adjusted risk ratios for 7-year total mortality were 1.07 (95% CI=0.61-1.88) for the mid tertile of uric acid level and 1.24 (95% CI=0.70-2.20) for the top tertile. In women, the multiply adjusted risk ratios were 0.58 (95% CI=0.29-1.18) and 0.47 (95% CI=0.22-0.99), for the mid and top tertiles respectively. CRP and IL-6 were important confounders in the relationship between serum uric acid and overall mortality. High serum uric acid level is not independently associated with increased total mortality in high-functioning older men and women. When evaluating the association between serum uric acid and mortality, the potential confounding effect of underlying inflammation and other risk factors must be considered.

Is Serum Uric Acid Level Associated with All-Cause Mortality in High-Functioning Older Persons: MacArthur Studies of Successful Aging?

Is Serum Uric Acid Level Associated with All-Cause Mortality in High-Functioning Older Persons: MacArthur Studies of Successful Aging?

Allostatic load as a marker of cumulative biological risk: MacArthur studies of successful aging.

Allostatic load (AL) has been proposed as a new conceptualization of cumulative biological burden exacted on the body through attempts to adapt to life's demands. Using a multisystem summary measure of AL, we evaluated its capacity to predict four categories of health outcomes, 7 years after a baseline survey of 1,189 men and women age 70-79. Higher baseline AL scores were associated with significantly increased risk for 7-year mortality as well as declines in cognitive and physical functioning and were marginally associated with incident cardiovascular disease events, independent of standard socio-demographic characteristics and baseline health status. The summary AL measure was based on 10 parameters of biological functioning, four of which are primary mediators in the cascade from perceived challenges to downstream health outcomes. Six of the components are secondary mediators reflecting primarily components of the metabolic syndrome (syndrome X). AL was a better predictor of mortality and decline in physical functioning than either the syndrome X or primary mediator components alone. The findings support the concept of AL as a measure of cumulative biological burden.

Social relationships, social support, and patterns of cognitive aging in healthy, high-functioning older adults: MacArthur studies of successful aging.

This study examines the relationship of social ties and support to patterns of cognitive aging in the MacArthur Studies of Successful Aging (see L. F. Berkman et al., 1993), a cohort study of 1,189 initially high-functioning older adults. Baseline and longitudinal data provide information on initial levels as well as changes in cognitive performance over a 7.5-year period. Linear regression analyses revealed that participants receiving more emotional support had better baseline performance, as did those who were unmarried and those reporting greater conflict with network members. Greater baseline emotional support was also a significant predictor of better cognitive function at the 7.5-year follow-up, controlling for baseline cognitive function and known sociodemographic, behavioral, psychological, and health status predictors of cognitive aging. The findings suggest the potential value of further research on the role of the social environment in protecting against cognitive declines at older ages.

Social relationships, social support, and patterns of cognitive aging in healthy, high-functioning older adults: MacArthur Studies of Successful Aging.

This study examines the relationship of social ties and support to patterns of cognitive aging in the MacArthur Studies of Successful Aging (see L. F. Berkman et al., 1993), a cohort study of 1,189 initially high-functioning older adults. Baseline and longitudinal data provide information on initial levels as well as changes in cognitive performance over a 7.5-year period. Linear regression analyses revealed that participants receiving more emotional support had better baseline performance, as did those who were unmarried and those reporting greater conflict with network members. Greater baseline emotional support was also a significant predictor of better cognitive function at the 7.5-year follow-up, controlling for baseline cognitive function and known sociodemographic, behavioral, psychological, and health status predictors of cognitive aging. The findings suggest the potential value of further research on the role of the social environment in protecting against cognitive declines at older ages.

Cross-sectional and prospective relationships of interleukin-6 and C-reactive protein with physical performance in elderly persons: MacArthur studies of successful aging.

Chronic inflammation has been proposed as a biological mechanism underlying the decline in physical function that occurs with aging. The purpose of this investigation was to examine the cross-sectional and prospective relationships between markers of inflammation, interleukin-6 (IL-6) and C-reactive protein (CRP), with several measures of physical performance in older persons aged 70 to 79 years. Subjects were 880 high-functioning men and women participating in the MacArthur Study of Successful Aging (n = 1189), a subset of the Established Populations for Epidemiologic Studies of the Elderly (n = 4030). Plasma IL-6 and CRP levels were determined by enzyme-linked immunosorbent assay and log transformed to normalize the distributions. Physical function measures included handgrip strength, signature time, chair stands (time to complete five repetitions), and 6-m walk time. Women had lower (p < .05) IL-6 levels than men, but there was no significant difference between blacks and whites. IL-6 and CRP levels were higher (p < .05) in current smokers than in nonsmokers and in those with a greater body mass index (BMI). Hours per year undertaking moderate and strenuous physical activity were also related to inflammatory markers with higher (p < .001) IL-6 and CRP levels in less active individuals. After adjusting for age, sex, race, BMI, smoking status, use of nonsteroidal anti-inflammatory drugs, and prevalence of morbidity, those in the top two quartiles for walking speed had lower (p = .012) IL-6 levels than those in the bottom quartile. In addition, there was a trend (p = .038) for lower CRP levels in those with higher walking speed. CRP levels were also lower (p = .04) in individuals in the top quartile for grip strength. No significant differences were noted for chair stands or signature time performance. Repeat performance measures obtained on 405 subjects (67% of those eligible at baseline) obtained 7 years later had declined significantly (grip strength, 18%; signature time, 21%; walking speed, 31%; p < .001), except for the chair rise; however, baseline IL-6 and CRP were not associated with a change in performance. However, those who died or who were unable to undergo testing had higher baseline IL-6 and CRP levels (p < .01) and slower walking speed (p < .05). Although IL-6 has been shown to predict onset of disability in older persons and both IL-6 and CRP are associated with mortality risk, these markers of inflammation have only limited associations with physical performance, except for walking measures and grip strength at baseline, and do not predict change in performance 7 years later in a high-functioning subset of older adults.

Successful aging: implications for oral health.

The past few years have seen a growing emphasis in gerontology on the concept of "successful" or "robust" aging. This represents a major paradigm shift in the field from a focus on declines in physical and social functioning, assumptions of the aging process as a downward spiral, and studies on how to manage these declines. Leading the way toward this new perspective on aging, the MacArthur Studies of Successful Aging asked the fundamental question: "What genetic, biomedical, behavioral, and social factors are crucial to maintaining health and functional capacities in the later years?" These studies examined longitudinally a large cohort of independent elders on several physical, cognitive, emotional, and social parameters. Other researchers have focused on the theme of robust aging; however, common predictors have emerged, such as remaining active physically and cognitively, maintaining social contacts, and avoiding disease. This research is timely, given the expanding population of the oldest old, and with successive cohorts demonstrating the "compression of morbidity" phenomenon. Such a paradigm shift is critical in geriatric dentistry as well, where successful aging is evident in the growing number of older adults who have retained their natural dentition into advanced old age. This presentation draws parallels between successful aging at the systemic and oral health levels, with illustrations from epidemiologic studies that demonstrate trends in improved health and quality of life among newer cohorts of older adults.

High urinary catecholamine excretion predicts mortality and functional decline in high-functioning, community-dwelling older persons: MacArthur Studies of Successful Aging.

Catecholamine release is a marker of stress, and high plasma norepinephrine levels have been associated with increased mortality. The predictive value of high urinary catecholamine excretion for functional decline and mortality in healthier older persons has not been determined. We used data from the MacArthur Studies of Successful Aging to determine the effects of high urinary catecholamine excretion on 3- and 7-year mortality and functional decline. In 1988, 765 high-functioning older subjects provided complete overnight urine samples for norepinephrine and epinephrine, and 199 of these provided repeat samples in 1991. Subjects who were in the top tertile of urinary norepinephrine or epinephrine excretion in 1988 were considered high excreters; those in the top tertile in both 1988 and 1991 were considered sustained high excreters. We used bivariate and multivariate analysis to examine the relations between high catecholamine excretion and mortality and Rosow-Breslau functional decline in 1991 and 1995. In multivariate analyses, subjects with high baseline urinary excretion of epinephrine, norepinephrine, or either catecholamine were at higher risk for mortality and functional decline at 3 and 7 years, although the magnitude of risk (adjusted odds-ratios ranged from 1.1 to 3.1) varied depending upon specific catecholamine and outcome measure. Subjects who had sustained high urinary norepinephrine excretion were also at increased risk for 4-year mortality or functional decline. High urinary catecholamine excretion in high-functioning, community-dwelling older persons likely reflects subclinical sympathetic stimulation and is a marker of increased risk for functional decline and mortality.