Adult bone strength of children from single-parent families: the Midlife in the United States Study.

UNLABELLED: Bone health may be negatively impacted by childhood socio-environmental circumstances. We examined the independent associations of single-parent childhood and parental death or divorce in childhood with adult bone strength indices. Longer exposure to a single-parent household in childhood was associated with lower bone strength in adulthood. INTRODUCTION: Because peak bone mass is acquired during childhood, bone health may be negatively impacted by childhood socio-environmental disadvantage. The goal of this study was to determine whether being raised in a single-parent household is associated with lower bone strength in adulthood. METHODS: Using dual-energy X-ray absorptiometry data from 708 participants (mean age 57 years) in the Midlife in the United States Biomarker Project, we examined the independent associations of composite indices of femoral neck bone strength relative to load (in three failure modes: compression, bending, and impact) in adulthood with the experience of single-parent childhood and parental death or divorce in childhood. RESULTS: After adjustment for gender, race, menopause transition stage, age, and body mass index, each additional year of single-parent childhood was associated with 0.02 to 0.03 SD lower indices of adult femoral neck strength. In those with 9-16 years of single-parent childhood, the compression strength index was 0.41 SD lower, bending strength index was 0.31 SD lower, and impact strength index was 0.25 SD lower (all p values < 0.05). In contrast, parental death or divorce during childhood was not by itself independently associated with adult bone strength indices. The magnitudes of these associations were unaltered by additional adjustment for lifestyle factors and socioeconomic status in childhood and adulthood. CONCLUSIONS: Independent of parental death or divorce, growing up in a single-parent household is associated with lower femoral neck bone strength in adulthood, and this association is not entirely explained by childhood or adult socioeconomic conditions or lifestyle choices.

Socioeconomic status, race, and bone turnover in the Midlife in the US Study.

UNLABELLED: Among a group of 940 US adults, economic adversity and minority race status were associated with higher serum levels of markers of bone turnover. These results suggest that higher levels of social stress may increase bone turnover. INTRODUCTION: To determine socioeconomic status (SES) and race differences in levels of bone turnover. METHODS: Using data from the Biomarker Substudy of the Midlife in the US (MIDUS) study (491 men, 449 women), we examined cross-sectional associations of SES and race with serum levels of bone turnover markers (bone-specific alkaline phosphatase [BSAP], procollagen type I N-terminal propeptide [PINP], and N-telopeptide [Ntx]) separately in men and women. Linear multivariable regression was used to control for body weight, menopausal transition stage, and age. RESULTS: Among men, low family poverty-to-income ratio (FPIR) was associated with higher turnover, but neither education nor race was associated with turnover. Men with FPIR <3 had 1.808 nM BCE higher Ntx (P = 0.05), 3.366 U/L higher BSAP (P = 0.02), and 7.066 higher PINP (P = 0.02). Among women, neither education nor FPIR was associated with bone turnover, but Black women had 3.688 nM BCE higher Ntx (P = 0.001), 5.267 U/L higher BSAP (P = 0.005), and 11.906 µg/L higher PINP (P = 0.008) compared with non-Black women. CONCLUSIONS: Economic adversity was associated with higher bone turnover in men, and minority race status was associated with higher bone turnover in women, consistent with the hypothesis that higher levels of social stresses cause increased bone turnover. The magnitude of these associations was comparable to the effects of some osteoporosis medications on levels of turnover.

Price of adaptation--allostatic load and its health consequences. MacArthur studies of successful aging.

BACKGROUND: Exponential growth in the population of older adults presents clinicians with special concerns about factors affecting risks for declines in cognitive and physical functioning. OBJECTIVES: To examine the hypothesis that risks for such declines and for disease outcomes, such as cardiovascular disease, are related to differences in allostatic load, the cumulative physiologic toll exacted on the body over time by efforts to adapt to life experiences. To present an operational definition of allostatic load, along with preliminary evidence of its predictive validity in relation to salient outcomes of aging. METHODS: Data from a longitudinal, community-based study of successful aging were used to develop a measure of allostatic load based on 10 parameters reflecting levels of physiologic activity across a range of important regulatory systems. Allostatic load is the sum of the number of parameters for which the subject was rated in the highest-risk quartile. RESULTS: Higher allostatic load scores were associated with poorer cognitive and physical functioning and predicted larger decrements in cognitive and physical functioning as well as being associated with an increased risk for the incidence of cardiovascular disease, independent of sociodemographic and health status risk factors. CONCLUSIONS: Findings are consistent with the conceptualization of allostatic load as an index of wear and tear on the body, with elevations in allostatic load predicting an increased risk for a decline in cognitive and physical functioning as well as cardiovascular disease in a cohort of older men and women. From a clinical perspective, the concept of allostatic load may provide the basis for a more comprehensive assessment of major risks in the aging process.

Functional disability before myocardial infarction in the elderly as a determinant of infarction severity and postinfarction mortality.

BACKGROUND: Functional disability is a common condition among elderly patients. However, to our knowledge, its effect on outcome of myocardial infarction (MI) has not been assessed. Our objectives were to determine whether disability in the activities of daily living measured before MI is a predictor of MI severity and mortality. METHODS: Disability in activities of daily living was measured prospectively in a cohort of 222 patients who were hospitalized with acute MI. Outcome measures were severity characteristics on admission to the hospital (higher Killip class, presence of new Q waves in the first electrocardiogram, and lower systolic blood pressure), and 6-month mortality. RESULTS: Patients with disability before hospitalization were older and had more comorbidity. After adjusting for these factors and for delay in hospital arrival, disability was still significantly associated with clinical severity on admission to the hospital and with mortality (adjusted relative risk of death for patients with disability vs patients without disability, 2.01; 95% confidence interval, 1.23-3.28). Clinical severity and hospital treatment explained the higher mortality of patients with disability. When these factors were added to the previous model, the relative risk of mortality for patients with disability vs patients without disability was 1.24, and the 95% confidence interval was 0.73 to 2.12. CONCLUSIONS: Functional disability in activities of daily living before MI is an important predictor of clinical severity and mortality in elderly patients with MI. This effect is only minimally explained by the older age and higher comorbidity of patients with disability. However, higher clinical severity and lower use of treatment interventions are major determinants of their higher mortality compared with patients without disability.

Increase in urinary cortisol excretion and memory declines: MacArthur studies of successful aging.

Cortisol production is increased during stress, and the actions of cortisol on receptors in the brain and other body organs are involved in allostasis, the process of adaptation to stress, as well as in allostatic load, the wear and tear associated with excessive exposure to cortisol. Using data from a community-based longitudinal study of older men and women, aged 70-79 yr, we tested the hypothesis that exposure to increasing levels of cortisol is associated with declines in memory performance. Associations between 12-h urinary free cortisol excretion and performance on tests of memory (delayed verbal recall and spatial recognition), abstraction, and spatial ability were examined. Among the women, greater cortisol excretion was associated with poorer baseline memory performance, independent of socio-demographic, health status, health behavior, and psychosocial characteristics. Moreover, women who exhibited increases in cortisol excretion over a 2.5-yr follow-up period were more likely to show declines in memory performance. By contrast, women who experienced declines in cortisol exhibited improvements in memory performance. No significant associations were found among the men. The results for the women suggest that decrements in memory performance associated with increases in cortisol may not represent irreversible effects, as declines in cortisol were associated with improvements in memory.

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

OBJECTIVE: 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. METHODS: 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). RESULTS: 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. CONCLUSIONS: 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.

Plasma homovanillic acid and performance on motor and cognitive tasks in community-dwelling elderly: MacArthur studies of successful aging.

To investigate the dopaminergic correlates of the aging-related motor and cognitive deficits, the dopamine metabolite homovanillic acid (HVA) in plasma was studied in a community-dwelling elderly cohort (n = 141). The results showed that hand-signature time (HST), a measure of bradykinesia, correlated negatively with plasma HVA (r = -0.24, p < .007). Similarities task performance showed a trend-level positive correlation with plasma HVA (r = 0.15, p = .08). Because plasma HVA is derived from several sources including central dopaminergic neurons and both central and peripheral noradrenergic neurons, the noradrenergic metabolite 3-methoxy-4-hydroxyphenylglycol (MHPG) in plasma was also measured to indirectly estimate the relationships, with HVA originating from noradrenergic metabolism. Plasma MHPG significantly correlated with similarities scores (r = 0.34, p < .001) but not with HST. The results suggested that the association of HVA with prolonged HST may be related to central dopamine metabolism, but its association with similarities scores may be due to noradrenergic metabolism. The results raise the possibility that prolonged HST may be an indicator of preclinical brain dopamine loss in the elderly.

Social ties and health: the benefits of social integration.

This article explores the relationship between level of social integration and various aspects of health. A search of the literature published since the mid-1970s (under the MEDLINE key words, "social ties," "social network," "social isolation," "social environment") presented strong evidence that social integration leads to reduced mortality risks, and to a better state of mental health. The evidence on physical health outcomes is less conclusive. There is no consistent evidence that social integration affects the incidence of disease (at least for cardiovascular outcomes). However, social integration does appear to have a highly beneficial effect on post-myocardial infarction prognosis (functioning and longevity). A physiologic basis for these effects on health outcomes is also indicated by research demonstrating that both social isolation and nonsupportive social interactions can result in lower immune function and higher neuroendocrine and cardiovascular activity while socially supportive interactions have the opposite effects. In conclusion, available data suggest that, although social integration is generally associated with better health outcomes, the quality of existing ties also appears to influence the extent of such health benefits. Clearly, individuals' networks of social relationships represent dynamic and complex social systems that affect health outcomes.

Intercommunity variations in the association between social ties and mortality in the elderly. A comparative analysis of three communities.

Identical measures of social ties obtained from three community-based cohorts aged 65 and over from East Boston, MA; New Haven, CT; and two rural counties in Iowa permit the first direct cross-community comparison of the hypothesis that social isolation increases 5-year mortality risks (1982 to 1987) for older men and women. In sex-specific proportional hazards analyses, social ties were significantly and inversely related to mortality independently of age in all three cohorts (e.g., relative hazard (RH) = 1.97 to 3.06 for men and women, comparing those with no ties to those with four types of ties). After controlling for age, pack-years of smoking, body mass, chronic conditions, angina, and physical and cognitive disability, social ties remain significant predictors of mortality risk for the men and women in New Haven (RH = 2.4 and 1.8) and for women in Iowa (RH = 1.9). For the men in Iowa (RH = 1.4) and the men and women in East Boston (RH = 1.0 and 1.3), the associations are weaker and nonsignificant.

Gender differences in patterns of HPA axis response to challenge: Macarthur studies of successful aging.

Previous research has suggested that women may have greater and more prolonged hypothalamic-pituitary-adrenal response to challenge at older ages. Data on patterns of ACTH and cortisol responses to a "naturalistic" driving simulation challenge were examined to test the hypothesis that older women (aged 70-79 years) would show greater response than a comparable group of older men. Analyses of mean ACTH or cortisol responses in terms of maximal increase, area under the curve and repeated measures ANOVA did not reveal significant gender differences. By contrast, analyses of the joint occurrence of ACTH and cortisol responses above the respective sample medians indicated that women were significantly more likely to respond to the challenge with elevated ACTH and cortisol responses. The lack of significant gender difference in the analyses of mean scores resulted from the sensitivity of this measure of typically (or average response) to outliers in the data, thereby substantially distorting the report of typical (or average) responses for the male population. Analyses of the temporal patterns of ACTH and cortisol response in terms of the stability of the subject's relative rank at each sampling time indicated that: (1) there was considerable stability of rankings based on the initial cortisol response (though not ACTH) through the recovery period; and (2) women exhibited greater instability than men, being more likely to exhibit shifts in rank from high to low over time. These findings suggest that: (1) as a group, older women are more likely to show larger responses than comparably healthy older men to a "naturalistic" driving simulation challenge; (2) there is considerable stability in patterns of cortisol response from initial response at 20 min through the recovery period, indicating that those showing greater initial response continue to experience higher levels of cortisol during the post-challenge recovery period; and (3) instability is more common among women than men.

Gender differences in age-related changes in HPA axis reactivity.

Possible differences between men and women in age-related patterns of hypothalamic-pituitary-adrenal (HPA) axis response to challenge were examined to test the hypothesis that women show greater age-related increase in HPA axis reactivity to challenge. Twenty-six younger subjects, 9 men and 17 women, ages 22-26 and 14 older subjects, 7 men and 7 women, ages 67-88 participated in the study. Patterns of change in salivary "free" cortisol were measured in response to a standardized, 30-minute cognitive challenge, administered individually to each subject beginning at 1600 h. Consistent with previous research, there was a significant main effect for age with respect to baseline cortisol: older age was associated with higher baseline cortisol (P = <0.001). Results also provide support for the hypothesized age-by-gender interaction with respect to patterns of response to challenge. There was a significant interaction with respect to maximum percentage increase over baseline (P < 0.002): among younger adults, the men exhibited greater increases whereas among the older adults, the women exhibited greater increases. A similar, though only marginally significant pattern was seen for total area under the response curve (P = 0.07). Repeated measures ANOVA confirmed the gender-by-age differences in the patterns of response (P = 0.01 for time*age*gender interaction).

High, usual and impaired functioning in community-dwelling older men and women: findings from the MacArthur Foundation Research Network on Successful Aging.

The objective of this study is to determine the range of complex physical and cognitive abilities of older men and women functioning at high, medium and impaired ranges and to determine the psychosocial and physiological conditions that discriminate those in the high functioning group from those functioning at middle or impaired ranges. The subjects for this study were drawn from men and women aged 70-79 from 3 Established Populations for the Epidemiologic Study of the Elderly (EPESE) programs in East Boston MA, New Haven CT, and Durham County NC screened on the basis of criteria of physical and cognitive function. In 1988, 4030 men and women were screened as part of their annual EPESE interview. 1192 men and women met criteria for "high functioning". Age and sex-matched subjects were selected to represent the medium (n = 80) and low (n = 82) functioning groups. Physical and cognitive functioning was assessed from performance-based examinations and self-reported abilities. Physical function measures focused on balance, gait, and upper body strength. Cognitive exams assessed memory, language, abstraction, and praxis. Significant differences for every performance-based examination of physical and cognitive function were observed across functioning groups. Low functioning subjects were almost 3 times as likely to have an income of < or = $5000 compared to the high functioning group. They were less likely to have completed high school. High functioning subjects smoked cigarettes less and exercised more than others. They had higher levels of DHEA-S and peak expiratory flow rate. High functioning elders were more likely to engage in volunteer activities and score higher on scales of self-efficacy, mastery and report fewer psychiatric symptoms.

Is serum uric acid level associated with all-cause mortality in high-functioning older persons: MacArthur studies of successful aging?

OBJECTIVES: 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. DESIGN: Prospective cohort study. SETTING: A sample of community-dwelling older people. PARTICIPANTS: A cohort of 870 participants from the MacArthur Studies of Successful Aging. MEASUREMENTS: 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. RESULTS: 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. CONCLUSIONS: 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.

Moderate-intensity aerobic training improves glucose tolerance in aging independent of abdominal adiposity.

OBJECTIVE: To test the hypothesis that training-related improvements in glucose and insulin responses to an oral glucose tolerance test (OGTT) are independent of changes in abdominal adiposity. DESIGN: Adiposity and responses to an OGTT were measured before and after a 4-month randomized, controlled aerobic training program. SETTING: An academic medical institution. PARTICIPANTS: Sixteen healthy older (73+/-1 year) men and women. INTERVENTION: Both the training (T) (n=9) and control (C) (n=7) groups exercised 4 times a week for 60-minute sessions. T exercised on mini-trampolines at 55 to 65% of HRmax (determined from a graded treadmill test) for 1 month and then at 75% for 3 months; C engaged in supervised stretching and yoga. MEASUREMENTS: At baseline and follow-up, we estimated abdominal fat (from computed tomography and anthropometry), plasma glucose, and serum insulin responses to the OGTT and fasting concentrations of free fatty acids (FFA). RESULTS: Aerobic training resulted in a 16% increase in VO2 peak and a 24% decrease in FFA in the T group (P < .05), but training had no effect on abdominal fat. In the T group, the glucose response curve shifted to the left, and the incremental area under the glucose curve decreased by 25% (P < .05). This improvement in glucose response occurred, however, only in those with impaired glucose tolerance at baseline and without any observed change in insulin response. No change in any variables occurred in the C group. CONCLUSIONS: Our data suggest that moderate-intensity aerobic training has a favorable effect on glucose tolerance in older people, independent of changes in abdominal adiposity.

The relation between cortisol excretion and fractures in healthy older people: results from the MacArthur studies-Mac.

BACKGROUND: In persons with depression, higher urinary cortisol is associated with lower bone mineral density. OBJECTIVE: To examine the relation between urinary free cortisol (UFC) and fractures. SETTING: Community-based samples from Durham, NC, East Boston, MA, and New Haven, CT. PARTICIPANTS: 684 men and women, aged 70 to 79 at baseline, who were part of the MacArthur Study of Successful Aging. DESIGN: Cohort study. Participants with previous history of fractures at baseline were excluded. MEASURES: The primary exposure variable was overnight (8:00 p.m. to 8:00 a.m.) UFC (microg/g creatinine) at baseline (1988). Outcomes were self-reported hip, arm, spine, wrist, or other fracture during the follow-up period (1988-1995). Covariates were baseline age, gender, race, body mass index, current physical activity, lower extremity strength, depression subscale of the Hopkins Symptom Checklist, and current use of cigarettes and alcohol. ANALYSIS: Logistic regression was used to predict the occurrence of incident fractures (1988-1995) as a function of quartiles of baseline UFC. Models were adjusted for age, gender, and race and were also multiply adjusted for the remaining covariates listed above. Gender-stratified models and models that excluded corticosteroid users were also run. RESULTS: In multiply adjusted models, higher baseline levels of UFC were significantly associated with incident fractures. Odds of fracture (95% Confidence Intervals) for increasing quartiles of baseline UFC, multiply adjusted, were: 2.28 (.91, 5.77); 3.40 (1.33, 8.69); 5.38 (1.68, 17.21). Results were not materially influenced by exclusion of persons using corticosteroids. CONCLUSIONS: Higher baseline UFC is an independent predictor of future fracture.

The predictive value of combined hypoalbuminemia and hypocholesterolemia in high functioning community-dwelling older persons: MacArthur Studies of Successful Aging.

OBJECTIVES: To examine the effect of simultaneous hypoalbuminemia and hypocholesterolemia levels on 3- and 7-year rates of mortality and decline in functional status. METHODS: In this cohort study, 937 community-based persons aged 70 to 79 years in 1988, who had high baseline physical and cognitive functioning, were classified into four groups: Group 1 (low albumin, low cholesterol), Group 2 (low albumin, normal cholesterol), Group 3 (normal albumin, low cholesterol) and Group 4 (normal albumin, normal cholesterol) using baseline blood values. Crude and multiply adjusted rates of (1) mortality (2) decline in Rosow-Breslau (RB) functional status, and (3) mortality or decline in RB functional status in 1991 and 1995 were calculated. RESULTS: Group 1 subjects had multiply adjusted relative risks (ARR) of 3.62 and 3.53 for 3-and 7-year mortality compared with Group 4. Group 1 subjects had ARRs of 3.82, 3.02, and 2.67 of 3-year mortality or decline in RB activity scale when compared with Groups 4, 2, and 3, respectively. CONCLUSIONS: Concomitant low serum cholesterol and albumin levels may identify high functioning older persons who are at increased risk of subsequent mortality and functional decline.

Sex differences in survival after myocardial infarction in older adults: a community-based approach.

OBJECTIVE: To determine sex differences in survival after myocardial infarction in older individuals. DESIGN: Prospective cohort study based on a community sample of older individuals. All patients were followed for 1 year after hospital admission. SETTING: Two hospitals in New Haven, Connecticut. PARTICIPANTS: The study included 103 women and 120 men who were participants in the New Haven, CT cohort of the Established Populations for the Epidemiologic Study of the Elderly (EPESE) program and who were diagnosed with myocardial infarction between the inception of the community study in 1982 and December 31, 1992. The mean age of women was 79.3 and of men, 77.3. MEASUREMENTS: Data on clinical characteristics were abstracted from medical records. Sociodemographic, psychosocial, and physical function information was derived from the EPESE interview preceding the infarction. The main outcome measure was all-cause mortality, for which three end points were used: early mortality (first 30 days), late mortality (1-year mortality among survivors of the first 30 days), and overall mortality (1-year mortality from admission in the whole sample). RESULTS: Mortality in the first 30 days did not differ significantly in the two sexes. The relative risk (RR) of death in women compared with men was 0.85 (95% confidence interval [CI], 0.49-1.47) before multivariable adjustment; this was unchanged after adjustment for demographic factors, comorbidity, functional status, psychosocial factors, and clinical severity (RR, 0.85, 95% CI, 0.41-1.76). Among survivors of 30 days, women were almost two times more likely to survive at 1 year compared with men, both before multivariable adjustment (RR, 0.56, 95% CI, 0.31-1.02) and after controlling for demographic factors, comorbidity, physical function, psychosocial factors, clinical severity on admission, and hospital complications (RR, 0.44 ; 95% CI, 0.20-0.99). Analyses involving 1-year follow-up from admission for the entire sample yielded intermediate results. CONCLUSION: There was little difference in mortality in the first 30 days after myocardial infarction between older men and women, but when the early deaths were excluded, women showed an increased survival compared with men in the first year after the myocardial infarction.

Measured versus estimated creatinine clearance in a high-functioning elderly sample: MacArthur Foundation Study of Successful Aging.

OBJECTIVE: To assess the validity of several equations for estimating creatinine clearance in a large sample of high-functioning, community-dwelling elderly. DESIGN: Serum and 12-hour urine samples were collected and assayed for creatinine using the Jaffe total chromagen method. Fifteen clearance-estimating equations were evaluated for bias, accuracy, correlation with measured clearance values, and frequency of erroneous placement into renal function categories. Stepwise regression modeling and reliability testing were performed on a split sample to construct and assess a novel creatinine-clearance-estimating equation. SETTING: New Haven, Connecticut, East Boston, Massachusetts, and a five-county region in and around Durham, North Carolina. PARTICIPANTS: A subsample of community-dwelling men and women (age range 70-79 years) from the Established Populations for Epidemiological Studies of the Elderly was screened for physical and cognitive functioning and placed into high-, medium-, and low-functioning groups (n = 1354). High-functioning respondents who provided blood and complete urine samples (n = 762) were included in the present study. RESULTS: In general, estimated creatinine clearance was more closely correlated to measured values in males than in females. Most equations underestimated creatinine clearance, with average bias ranging from -33.1 mL/min to +19.6 mL/min. Predictive accuracy ranged from 18.2 mL/min to 38.0 mL/min. Equations were variable in their erroneous placement of individuals into renal function categories. Regression modeling yielded an equation which contained novel components but failed to provide better estimates of creatinine clearance than those already available. CONCLUSIONS: The equations evaluated here provide unacceptable predictions of creatinine clearance in normally aging individuals. We advocate the use of serum drug concentration measurements when available and encourage investigation into timed urine collections of short duration as alternatives to clearance-estimating equations in the elderly.

Social environment effects on health and aging: integrating epidemiologic and demographic approaches and perspectives.

This paper provides an overview of epidemiological and demographic research linking social characteristics of both individuals and communities to differences in both morbidity and mortality risks. Evidence is presented linking three broad aspects of the social environment to health--the network of personal social relationships within which most of us live our lives, individual socioeconomic status (SES), and community-level social characteristics. Large and consistent bodies of literature from both epidemiology and demography provide clear evidence for the generally health-promoting effects of personal social relationships and SES. The bulk of the evidence relates to mortality although both fields have begun to examine other health outcomes, including aspects of physical and cognitive functioning as well as disease outcomes. A smaller but growing body of community-level data, reflecting both the socioeconomic/resource characteristics of these broader communities and, more specifically, social features of these environments, also point to health impacts from these more macro level social environment characteristics. Much remains to be elucidated, however, concerning the actual mechanisms through which something as complex and multifaceted as SES "gets under the skin." This necessarily includes consideration of external characteristics of the environments (both physical and sociocultural) where people live and work, and individual characteristics, as well as possible interactions between these in producing the observed SES gradients in health and mortality. These questions concerning links between social environment conditions and health may be a particularly fruitful area of future collaboration, drawing on the shared interest of demographers and epidemiologists in understanding how different social conditions promote variation in distributions of better versus worse health outcomes within a population.

Psychosocial resources and the SES-health relationship.

Psychosocial resources, which include optimism, coping style, a sense of mastery or personal control, and social support, influence the relationship between SES and health. To varying degrees, these resources appear to be differentially distributed by social class and related to health outcomes. Such resources may partially mediate the impact of SES on health. For example, environments that undermine personal control may have an impact on chronic arousal and the corresponding development of disease, such as CHD. Psychosocial resources may also moderate the impact of SES on health. For example, a large number of positive social relationships and a few conflictual ones may buffer individuals against the adverse effects of SES-related stress. These psychosocial resources are moderately intercorrelated, and so a research strategy that explores their coherence as a psychosocial profile that promotes resilience to stress is tenable and merits empirical examination. The erosion of these resources as one moves lower on the SES scale and specific factors that contribute to such erosion are discussed.