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Scholars have debated the legitimacy of gerontology as a discipline since Metchnikoff coined the term more than 100 years ago. Recent developments such as the emergence of interdisciplinary aging theories and consensus on longitudinal research methods suggest that gerontology is materializing as a unique discipline, rather than a subset of another more established disciplinary tradition. In this article we review substantive evidence from gerontological theory and scholarship to suggest orienting principles for the emerging discipline of gerontology. We offer a conceptual framework of gerontology as a discipline that integrates contributions of biopsychosocial perspectives with well-established concepts of age, aging, and aged and multiple contextual elements. We conclude with a discussion of how our model relates to gerontology's progress, including examples of successful interdisciplinary research, and offer questions for gerontologists to consider for further advancement of the field.

Burawoy (2005) argues that sociology needs to re-establish a public sociology oriented toward society's problems and the practice of its unique knowledge if it is to again be taken seriously by the public, policymakers, and others. Yet, it is unclear how best to achieve these goals. We argue that the relatively young field of social gerontology provides a useful model of successful public sociology in action. As a multidisciplinary field engaged in basic and applied research and practice, social gerontology's major aim is to improve the lives of older people and to ameliorate problems associated with age and aging. Thus social gerontology has routinely reached beyond the academy to engage with its publics. We review the field's historical and theoretical development and present four examples of public sociology in action. Several factors have contributed to social gerontology's success in achieving the goals of public sociology: (1) Working in multidisciplinary teams which promote collaboration and respect for diverse perspectives. (2) Its ability to advocate "professionally" for its publics without favoring one group at the expense of another. (3) The unique affinity of its theories and practices with its disciplinary values. (4) The constructive effects of its ongoing questioning of values and ethics. Working in a multidisciplinary field with multiple publics, social gerontologists have been able to blend professional, critical, policy, and public sociologies to a considerable degree while contributing toward improvements in well-being.

Background. The influence of long-term adult weight history on metabolic risk independent of attained body mass index (BMI) is unknown. Methods. Using nationally representative data on adults aged 50-64 years from the 1999-2006 National Health and Nutrition Examination Surveys, we examined weight change for two periods of adulthood: prime age (age 25-10 years ago) and midlife (the last 10 years). Weight changes in each period were categorized as stable (gain Results. Participants in the gain-stable group had 89% elevated odds of metabolic syndrome (odds ratio = 1.89, 95% CI: 1.19-3.01) relative to the stable-stable group, even after adjustment for current BMI. All weight gain groups had increased odds of low HDL and high triglycerides relative to participants with continuously stable weights. No significant associations were found between weight history and hypertension or high glucose. Conclusions. Weight history confers information about metabolic risk factors above and beyond attained weight status. In particular, adult weight gain is related to risk of low HDL and high triglycerides. Weight history may contribute to our understanding of why some obese older persons are metabolically healthy but others are not. Key Words: Metabolic syndrome--Weight history--Body mass index--Lipids. doi: 10.1093/gerona/glp177

Background. Although both obesity and the metabolic syndrome (MetS) are known risk factors for decline in physical function, the joint association of obesity and metabolic alterations with risk of incident mobility limitation is unknown. Methods. Data are from 2,984 women and men aged 70-79 years participating in the Health, Aging, and Body Composition Study without mobility limitation at baseline. Obesity was defined as body mass index greater than or equal to 30 kg/[m.sup.2] and the MetS as meeting greater than or equal to 3 of the ATP III criteria. Mobility limitation was defined as any difficulty walking one-quarter mile or climbing 10 steps during two consecutive semiannual assessments for more than 6.5 years. Results. Incidence of mobility limitation was 55% in women and 44% in men. In women, adjusted risk of developing mobility limitation was progressively greater in nonobese participants with the MetS (hazard ratio [HR] = 1.49, 95% confidence interval [CI] = 1.24-1.80), obese participants without the MetS (HR = 1.95, 95% CI = 1.51-2.53), and obese participants with the MetS (HR = 2.16, 95% CI = 1.78-2.63) relative to the nonobese without the MetS. In men, the corresponding adjusted HRs (95% CI) were 1.07 (0.87-1.32), 1.64 (1.19-2.25), and 1.41 (1.12-1.78). Elevated inflammatory markers partly explained the association between obesity, the MetS, and mobility limitation, particularly in nonobese and obese participants with the MetS. Conclusions. Obesity itself, independent of its metabolic consequences, is a risk factor for mobility limitation among obese older adults. In addition, having the MetS increases the risk of functional decline in older nonobese women but not in men. Key Words: Obesity--Metabolic syndrome--Mobility limitation--Inflammation--Older people. doi: 10.1093/gerona/glp150

Background. Inflammatory proteins including interleukin-6 (IL-6) and C-reactive protein (CRP) have been associated with incident cognitive impairment, but little research has addressed their effects on the rate of cognitive change, and findings are mixed. The purpose of this study was to examine the relationship between serum levels of IL-6 and CRP and the rate of cognitive change across a range of cognitive domains in a sample of healthy older persons. Methods. Growth curve analysis was performed on data from the MacArthur Study of Successful Aging, a longitudinal cohort study of high-functioning older adults aged 70-79 years at baseline in 1988 and reinterviewed in 1991 and 1995 (N = 851). Individual growth curve parameters were derived from baseline and follow-up performance in abstraction, language, spatial ability, verbal recall, spatial recognition, and global cognitive function based on age, IL-6, CRP, and covariates. Results. Cross-sectionally, there is a generally linear negative relationship between inflammation and cognition, such that higher levels of inflammation are associated with lower levels of baseline cognitive function. After controlling for potential confounders, there was no effect of inflammation on baseline cognitive function or the rate of longitudinal cognitive change. However, persons in the top tertile on IL-6 were at an increased risk of incident declines on the Short Portable Mental Status Questionnaire (SPMSQ). Conclusions. Although high levels of inflammation are associated with incident cognitive impairment, these results do not generalize to the full range of cognitive changes, where the role of inflammation appears to be marginal. Key Words: Cognitive impairment--lntefleukin-6--C-reactive protein.

A study exploring the association between obesity and disability revealed that cardiovascular health has improved, but the risk of disability among obese people has increased.

Objectives. We examined biological risk profiles by race, ethnicity, and nativity to evaluate evidence for a Hispanic paradox in measured health indicators. Methods. We used data on adults aged 40 years and older (n=4206) from the National Health and Nutrition Examination Surveys (1999-2002) to compare blood pressure, metabolic, and inflammatory risk profiles for Whites, Blacks, US-born and foreign-born Hispanics, and Hispanics of Mexican origin. We controlled for age, gender, and socioeconomic status. Results. Hispanics have more risk factors above clinical risk levels than do Whites but fewer than Blacks. Differences between Hispanics and Whites disappeared after we controlled for socioeconomic status, but results differed by nativity. After we controlled for socioeconomic status, the differences between foreign-born Hispanics and Whites were eliminated, but US-born Mexican Americans still had higher biological risk scores than did both Whites and foreign-born Mexican Americans. Conclusions. There is no Hispanic paradox in biological risk profiles. However, our finding that foreign-born Hispanics and Whites had similar biological risk profiles, but US-born Mexican Americans had higher risk, was consistent with hypothesized effects of migrant health selectivity (healthy people in-migrating and unhealthy people out-migrating) as well as some differences in health behaviors between US-born and foreign-born Hispanics.

Although education is consistently related to better cognitive performance, findings on the relationship between education and age-associated cognitive change have been conflicting. Using measures of multiple cognitive domains from four waves of the Asset and Health Dynamics of the Oldest Old study, a representative sample of Americans aged 70 years and older, the authors performed growth curve modeling to examine the relationships between education, initial cognitive score, and the rate of decline in cognitive function. More years of education were linked to better initial performance on each of the cognitive tests, and higher levels of education were linked to slower decline in mental status. However, more education was unrelated to the rate of decline in working memory, and education was associated with somewhat faster cognitive decline on measures of verbal memory. These findings highlight the role of early-life experiences not only in long-term cognitive performance but also in old-age cognitive trajectories. Keywords: education; socioeconomic status; cognition; memory; growth curve modeling

Background. Many studies that show improved health in older adults have relied on subjective measures of health. This article assesses changes in the physiological status of older Americans during the 1990s using biological measures of high-risk for morbidity and mortality. Methods. Changes in the prevalence of clinically-defined, high risk for 10 biological markers were assessed in respondents age 65 years and older from National Health and Nutrition Examination Surveys (NHANES) III (1988-1994) and IV (1999-2000). Results. Some changes in prevalence of high-risk values of biological markers indicate improved health among older adults in the 1990s: a 6% reduction in the prevalence of high-risk total cholesterol (p < .001) and a 7% reduction in the prevalence of high-risk homocysteine (p < .001). Other changes indicate worsening health: a 9% increase in the prevalence of high-risk systolic blood pressure (p < .01), a 10% increase in obesity (p < .001), and an 8 % increase in the prevalence of high-risk C-reactive protein (p < .001). These changes remained significant after adjusting for age, sex, and education. Results of logistic regressions indicate that changes in the frequency of medication usage, medication efficacy, prevalence of chronic disease, and diet explained some of these changes. Conclusions. Changes in the prevalence of high-risk values of biological markers in the 1990s are mixed. Greater use and effectiveness of lipid-lowering medication has contributed to the reduction in percentage of the population with high-risk lipid levels, and folate supplementation accounted for a decline in the percentage with high-risk homocysteine. However, increases in the percentage with high-risk systolic blood pressure occurred despite an increase in the use of antihypertensive medications, in part because of the limited ability of antihypertensive medications to bring blood pressure below high-risk levels.

Anthropometric measures including height provide an indication of childhood health that allows exploration of relationships between early life circumstances and adult health. Height can also be used to provide some indication of how early life health is related to selection of migrants and the Hispanic paradox in the United States. This article joins information on persons of Mexican nativity ages 50 and older in the United States collected in the National Health and Nutrition Examination Survey IV (NHANES IV 1999-2002) with a national sample of persons of the same age living in Mexico from the Mexican Health and Aging Survey (MHAS 2001) to examine relationships between height, education, migration, and late-life health. Mexican immigrants to the United States are selected for greater height and a high school, rather than higher or lower, education. Return migrants from the United States to Mexico are shorter than those who stay. Height is related to a number of indicators of adult health. Results support a role for selection in the Hispanic paradox and demonstrate the importance of education and childhood health as determinants of late-life health in both Mexico and the United States.