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Obesity is more prevalent and its consequences severe among middle-aged and older adults. Efforts to understand and address neighborhood-level causes of obesity in this population offer the potential to enhance health and reduce the costs of obesity for everyone. The accompanying paper by Li et al. (Am J Epidemiol. 2009;169(4):401–408) presents new data on the apparently significant interaction between neighborhood and individual characteristics on 1-year change in body weight and waist circumference. Despite methodological limitations in measurement, this paper supports the importance of future research that considers the complex relation between people and where they live. Efforts to design neighborhood-level policy interventions to effectively address the problem of obesity will require greater interdisciplinary collaboration. [ABSTRACT FROM AUTHOR]

A possible association between apolipoprotein E polymorphisms and age-related macular degeneration has been investigated numerous times, with conflicting results. A previous analysis pooling results from four studies (Schmidt et al., Ophthalmic Genet 2002;23:209–23) suggested an association, but those investigators did not document allele frequencies, the magnitude of the association, or the possible genetic mode of action. Thus, the authors searched MEDLINE from 1966 to December 2005 for any English-language studies reporting genetic associations. Data and study quality were assessed in duplicate. Pooling was performed while checking for heterogeneity and publication bias. Frequencies of the E2 and E4 alleles in Caucasians were approximately 8% and 15%, respectively. Allele- and genotype-based tests of association indicated a risk effect of up to 20% for E2 and a protective effect of up to 40% for E4. E2 appeared to act in a recessive mode and E4 in a dominant mode. There appears to be a differential effect of the E2 and E4 alleles on the risk of age-related macular degeneration, although the possibility of survivor bias needs to be ruled out more definitively. [ABSTRACT FROM PUBLISHER]

Although body build is related to disability and mortality in older people, the independent contributions of adiposity and lean mass are not fully defined. The authors examined the relations of body composition (fat mass index, fat-free mass index) and adiposity (body mass index, waist circumference) to ill health and physical disability in a cross-sectional study of 4,252 British men aged 60–79 years in 1998–2000. Increased body mass index, waist circumference, and fat mass index were associated with increased prevalence of cardiovascular disease, overall ill health, and disability. Adjusted odds ratios of cardiovascular disease (top vs. bottom fifth) were 1.58 (95% confidence interval (CI): 1.23, 2.03) for fat mass index, 1.45 (95% CI: 1.14, 1.86) for body mass index, and 1.27 (95% CI: 0.99, 1.62) for waist circumference. For overall “poor/fair” health, the corresponding odds ratios were 1.71 (95% CI: 1.33, 2.21), 1.49 (95% CI: 1.17, 1.90), and 1.64 (95% CI: 1.28, 2.09) and, for mobility limitation, they were 1.56 (95% CI: 1.17, 2.06), 1.96 (95% CI: 1.48, 2.56), and 1.88 (95% CI: 1.42, 2.49). A high fat-free mass index was associated with only a decreased prevalence of respiratory problems and cancer (odds ratios = 0.45 (95% CI: 0.33, 0.62) and 0.62 (95% CI: 0.42, 0.94), respectively). Body fatness, not fat-free mass, is associated with cardiovascular disease and disability in older men. Simple measures of overweight, such as body mass index and waist circumference, are good indicators of the likelihood of morbidity in older men. Prevention of weight gain with increasing age is likely to reduce morbidity and disability among older men. [ABSTRACT FROM AUTHOR]

Myeloperoxidase, an antimicrobial enzyme, produces oxidative free radicals. Rarely found in normal brain tissue, myeloperoxidase has been detected in microglia associated with Alzheimer's disease plaques. The authors examined a G-463A polymorphism in the promoter region of the myeloperoxidase gene (MPO) to determine the relation of MPO variants to cognitive decline over 4 years in a cohort of adults, aged 70–79 years at baseline (1997–1998), recruited from Memphis, Tennessee, and Pittsburgh, Pennsylvania, into the Health, Aging, and Body Composition Study. In this sample, 8% of the participants had the AA, 36.9% the AG, and 55.2% the GG genotype of MPO. The frequency of AA and AG genotypes was higher in Blacks than Whites (11.2% vs. 5.9%, and 44.1% vs. 32.9%, respectively). Multivariate logistic regression analyses showed that, for participants with the MPO AA genotype, cognitive decline was 1.58 (95% confidence interval: 1.07, 2.35) times more likely than for participants with the AG genotype and 1.96 (95% confidence interval: 1.33, 2.88) times more likely than for those with the GG genotype. Interactions between MPO and race, sex, or the apolipoprotein gene were not significant. In this sample, MPO AA, associated with decreased production of myeloperoxidase, was found to be a risk factor for cognitive decline. [ABSTRACT FROM AUTHOR]

There is growing recognition that the risk of many diseases in later life, such as type 2 diabetes or breast cancer, is affected by adult as well as early-life variables, including those operating prior to conception and during the prenatal period. Most of these risk factors are correlated because of common biologic and/or social pathways, while some are intrinsically ordered over time. The study of how they jointly influence later (distal) disease outcomes is referred to as life course epidemiology. This area of research raises several issues relevant to the current debate on causal inference in epidemiology. The authors give a brief overview of the main analytical and practical problems and consider a range of modeling approaches, their differences determined by the degree with which associations present (or presumed) among the correlated explanatory variables are explicitly acknowledged. Standard multiple regression (i.e., conditional) models are compared with joint models where more than one outcome is specified. Issues arising from measurement error and missing data are addressed. Examples from two cohorts in the United Kingdom are used to illustrate alternative modeling strategies. The authors conclude that more than one analytical approach should be adopted to gain more insight into the underlying mechanisms. [ABSTRACT FROM AUTHOR]

The authors evaluated underascertainment bias in Hispanic mortality rates from population surveys linked to the US National Death Index (NDI). They compared vital status through 7 years ascertained from an NDI search and from active follow-up for 2,886 Mexican-American subjects, aged ≥65 years at baseline in 1993–1994, from the Hispanic Established Populations for Epidemiologic Studies of the Elderly (EPESE). Estimates of NDI underascertainment were applied to mortality rate ratios for 66,667 older Mexican Americans and non-Hispanic Whites from the 1986–1994 National Health Interview Surveys linked to the NDI. The NDI and active follow-up agreed on vital status for 91.2% of Hispanic EPESE subjects. The NDI did not identify 177 deaths (20.7%) reported by proxies. Underascertainment was greater for women and when stratified by age and nativity. The ratios of proxy-reported to NDI mortality rates were 1.31 (95% confidence interval (CI): 1.06, 1.62) for immigrant men and 1.65 (95% CI: 1.32, 2.08) for immigrant women. Before adjustment, National Health Interview Surveys–NDI age-standardized mortality rate ratios comparing Mexican Americans with non-Hispanic Whites were 0.77 (95% CI: 0.65, 0.92) for men and 0.92 (95% CI: 0.77, 1.09) for women but were 0.84 and 1.18, respectively, with adjustment for underascertainment. Findings suggest that NDI-based Hispanic mortality rates may be understated. [ABSTRACT FROM AUTHOR]

The single and combined effects of three healthy lifestyle behaviors—nonsmoking, being physically active, and having a high-quality diet—on survival were investigated among older people in the SENECA Study. This European longitudinal study started with baseline measurements in 1988–1989 and lasted until April 30, 1999. The study population consisted of 631 men and 650 women aged 70–75 years from Belgium, Denmark, Italy, The Netherlands, Portugal, Spain, and Switzerland. A lifestyle score was calculated by adding the scores of the lifestyle factors physical activity, dietary quality, and smoking habits. The single lifestyle factors and the lifestyle score were related to mortality. Even at ages 70–75 years, the unhealthy lifestyle behaviors smoking, having a low-quality diet, and being physically inactive were singly related to an increased mortality risk (hazard ratios ranged from 1.2 to 2.1). The risk of death was further increased for all combinations of two unhealthy lifestyle behaviors. Finally, men and women with all three unhealthy lifestyle behaviors had a three- to fourfold increase in mortality risk. These results underscore the importance of a healthy lifestyle, including multiple lifestyle factors, and the maintenance of it with advancing age. [ABSTRACT FROM PUBLISHER]

Fractures of the proximal humerus, forearm, and wrist account for approximately one third of total osteoporotic fractures in the elderly. Several risk factors for these fractures were evaluated in this prospective study of 739 men and 1,105 women aged ≥60 years in Dubbo, Australia. During follow-up (1989-1996), the respective incidences of humerus and of forearm and wrist fractures, per 10,000 person-years, were 22.6 and 33.8 for men and 54.8 and 124.6 for women. Independent predictors of humerus fracture were femoral neck bone mineral density (FNBMD) (relative risk (RR) = 2.3, 95% confidence interval (CI): 1.2, 4.5) in men and FNBMD (RR = 2.4, 95% CI: 1.7, 3.5) and height loss (RR = 1.1, 95% CI: 1.0, 1.2) in women. For forearm and wrist fractures, risk factors were FNBMD (men: RR = 1.5, 95% CI: 1.0, 2.3; women: RR = 1.5, 95% CI: 1.2, 1.9) and height loss (men: RR = 1.2, 95% CI: 1.0, 1.3; women: RR = 1.1, 95% CI: 1.0, 1.2). In addition, dietary calcium (men: RR = 2.0, 95% CI: 1.0, 3.6) and a history of falls (women: RR = 1.9, 95% CI: 1.4, 2.6) were also significant. These data suggest that elderly men and women largely share common risk factors for upper limb fractures and that FNBMD is the primary risk factor. Am J Epidemiol 2001;153:587-595. [ABSTRACT FROM AUTHOR]

The authors carried out a study to investigate the association between different indicators of physical activity and the prevalence of impaired glucose tolerance (IGT) and newly diagnosed diabetes (nDM) in a population-based cohort of elderly men and women in the Netherlands. A sample of participants of the Rotterdam Study (n = 1,016) aged 55–75 years who were not known to have diabetes mellitus underwent an oral glucose tolerance test. Physical activity was assessed by means of a self-administered questionnaire and expressed as time spent on activities per week. Associations with the prevalence of IGT and nDM were assessed by logistic regression analysis after adjustment for age, body mass index, waist-hip ratio, family history of diabetes, and smoking. A total of 745 subjects had normal glucose tolerance, 153 IGT, and 118 nDM. The total amount of time spent on physical activity decreased with increasing glucose intolerance. Adjusted for main confounders, vigorous activities such as bicycling (men: odds ratio (OR) = 0.26, 95% confidence interval (CI) 0.14–0.49; women: OR = 0.37, 95% CI 0.18–0.78) and sports (men: OR = 0.28, 95% CI 0.11–0.74) showed an inverse association with the presence of nDM. For IGT, the associations pointed in the same direction but did not reach statistical significance. These results indicate that physical inactivity and glucose intolerance are associated among older adults similar to the way they are associated among middle-aged adults. Am J Epidemiol 1999;149:219–27. [ABSTRACT FROM AUTHOR]

Muscle mass decreases with age, leading to “sarcopenia, ” or low relative muscle mass, in elderly people. Sarcopenia is believed to be associated with metabolic, physiologic, and functional impairments and disability. Methods of estimating the prevalence of sarcopenia and its associated risks in elderly populations are lacking. Data from a population-based survey of 883 elderly Hispanic and non-Hispanic white men and women living in New Mexico (the New Mexico Elder Health Survey, 1993–1995) were analyzed to develop a method for estimating the prevalence of sarcopenia. An anthropometric equation for predicting appendicular skeletal muscle mass was developed from a random subsample(n = 199) of participants and was extended to the total sample. Sarcopenia was defined as appendicular skeletal muscle mass (kg)/height2 (m2) being less than two standard deviations below the mean of a young reference group. Prevalences increased from 13–24% in persons under 70 years of age to >50% in persons over 80 years of age, and were slightly greater in Hispanics than in non-Hispanic whites. Sarcopenia was significantly associated with self-reported physical disability in both men and women, independent of ethnicity, age, morbidity, obesity, income, and health behaviors. This study provides some of the first estimates of the extent of the public health problem posed by sarcopenia. Am J Epidemiol 1998; 147: 755–63. [ABSTRACT FROM PUBLISHER]

To estimate the prevalence of glucose intolerance in the elderly, oral glucose tolerance tests were performed as part of the Rotterdam Study, a population-based study in subjects aged 55 years and over. The study population consisted of 2, 668 men and 3, 950 women. Diabetes mellitus was defined as the use of antidiabetes medication, or a random or post-load serum glucose level of ≧11.1 mmol/liter. Impaired glucose tolerance was defined as a post-load serum glucose between 7.8 and 11.1 mmol/liter. In men, the frequency of diabetes mellitus ranged from 5.9% in ages ≪60 years to 19.8% in ages >85 years, and in women from 3.8% in ages ≪60 years to 18.9% in ages >85 years; more than half of the subjects with diabetes were newly diagnosed. The prevalence of impaired glucose tolerance ranged from 8.8% and 11.0% in men and women aged ≪60 years to 24.3% and 34.7% in men and women aged >85 years. The prevalence of diabetes mellitus in the total Rotterdam Study population of 7, 439 elderly men and women was estimated to be 11.3% (95% confidence interval (Cl) 10.5–12.0). Waist/hip ratio, systolic blood pressure, hypertension, and number of cigarettes smoked increased with a worsening of the glucose tolerance from normal, hyperinsulinemia, impaired glucose tolerance to diabetes in both men and women (p ≪ 0.01, adjusted for age). Body mass index was higher in subjects with glucose intolerance, but the frequency of obesity showed a relative decrease with worsening of glucose tolerance. These results show that glucose intolerance, especially impaired glucose tolerance and undetected diabetes mellitus, is common in the elderly. Moreover, not only subjects with diabetes mellitus but also subjects with hyperinsulinemia and Impaired glucose tolerance have an increase of cardiovascular risk factors. Am J Epidemiol 1997; 145: 24–32. [ABSTRACT FROM AUTHOR]

Bayes' theorem describes the effect of new information (e.g., a test result) on the probability of an outcome (e.g., a disease). Likelihood ratios for separate tests can be combined to assess the joint effect of their results on disease probability. This approach has been used to develop a test package for Alzheimer's disease that consists of some simple cognitive tests (Paired Associate Learning Test, Trailmaking Test, and Raven's Progressive Matrices) combined with age and family history of dementia. A total of 1,454 subjects who had been recruited into the Medical Research Council Elderly Hypertension Trial between 1983 and 1985 completed cognitive tests at entry to the trial (when they were without signs of dementia) and 1 month later. Their dementia status was ascertained in 1990–1991. The test package identified 52% of Alzheimer's disease cases with a 9% false-positive rate or 90% of Alzheimer's disease cases with a 29% false-positive rate. The author proposes the use of a similar test package in conjunction with a test for apolipoprotein E e4 status, which is a powerful risk factor for late-onset Alzheimer's disease, as a likelihood ratio approach to the prospective identification of Alzheimer's disease cases. This approach could be followed by ethically sound trials of new therapeutic agents for subjects who have a high probability of developing Alzheimer's disease. [ABSTRACT FROM AUTHOR]

Obesity in middle and old age predicts mobility limitation; however, the cumulative effect of overweight and/or obesity over the adult life course is unknown. The association between overweight and/or obesity in young, middle, and late adulthood and its cumulative effect on incident mobility limitation was examined among community-dwelling US adults aged 70–79 years at baseline (1997–1998) in the Health, Aging and Body Composition Study (n = 2,845). Body mass index was calculated by using recalled weight at ages 25 and 50 years and measured weight at ages 70–79 years. Mobility limitation (difficulty walking 1/4 mile (0.4 km) or climbing 10 steps) was assessed semiannually over 7 years of follow-up and was reported by 43.0% of men and 53.7% of women. Men and women who were overweight or obese at all 3 time points had an increased risk of mobility limitation (hazard ratio = 1.61, 95% confidence interval: 1.25, 2.06 and hazard ratio = 2.85, 95% confidence interval: 2.15, 3.78, respectively) compared with those who were normal weight throughout. Furthermore, there was a significant graded response (P < 0.0001) on risk of mobility limitation for the cumulative effect of obesity in men and overweight and/or obesity in women. Onset of overweight and obesity in earlier life contributes to an increased risk of mobility limitation in old age. [ABSTRACT FROM AUTHOR]

Age-related macular degeneration (AMD) is the leading cause of blindness among older people, and diet has been postulated to alter risk of AMD. To evaluate associations between red meat and chicken intake and AMD, the authors conducted a cohort study of 6,734 persons aged 58–69 years in 1990–1994 in Melbourne, Australia. Meat intake was estimated from a food frequency questionnaire at baseline. At follow-up (2003–2006), bilateral digital macular photographs were taken and evaluated for AMD (1,680 cases of early AMD, 77 cases of late AMD). Logistic regression was used to estimate odds ratios, adjusted for age, smoking, and other potential confounders. Higher red meat intake was positively associated with early AMD; the odds ratio for consumption of red meat ≥10 times/week versus <5 times/week was 1.47 (95% confidence interval: 1.21, 1.79; P-trend < 0.001). Similar trends toward increasing prevalence of early AMD were seen with higher intakes of fresh and processed red meat. Conversely, consumption of chicken ≥3.5 times/week versus <1.5 times/week was inversely associated with late AMD (odds ratio = 0.43, 95% confidence interval: 0.20, 0.91; P-trend = 0.007). These results suggest that different meats may differently affect AMD risk and may be a target for lifestyle modification. [ABSTRACT FROM AUTHOR]

The authors used data from a nationally representative survey of 933 adults aged 54 years or older (mean age = 66.2 years; standard deviation, 8.0) in Taiwan to explore whether mortality prediction at older ages is improved by the use of 3 clusters of biomarkers: 1) standard cardiovascular and metabolic risk factors; 2) markers of disease progression; and 3) nonclinical (neuroendocrine and immune) markers. They also evaluated the extent to which these biomarkers account for the female advantage in survival. Estimates from logistic regression models of the probability of dying between 2000 and 2006 (162 deaths; mean length of follow-up = 5.8 years) showed that inclusion of each of the 3 sets of markers significantly (P = 0.024, P = 0.002, and P = 0.003, respectively) improved discriminatory power in comparison with a base model that adjusted for demographic characteristics, smoking, and baseline health status. The set of disease progression markers and the set of nonclinical markers each provided more discriminatory power than standard risk factors. Most of the excess male mortality resulted from the men being more likely than women to smoke, but each of 3 markers related to disease progression or inflammation (albumin, neutrophils, and interleukin-6) explained more than 10% of excess male mortality. [ABSTRACT FROM AUTHOR]