Forecasting the obesity epidemic in the aging U.S. population

Which strategies reduce breast cancer mortality most? Collaborative modeling of optimal screening, treatment, and obesity prevention

BACKGROUND

US breast cancer mortality is declining, but thousands of women still die each year.

METHODS

Two established simulation models examine 6 strategies that include increased screening and/or treatment or elimination of obesity versus continuation of current patterns. The models use common national data on incidence and obesity prevalence, competing causes of death, mammography characteristics, treatment effects, and survival/cure. Parameters are modified based on obesity (defined as BMI ≥ 30 kg/m²). Outcomes are presented for the year 2025 among women aged 25+ and include numbers of cases, deaths, mammograms and false-positives; age-adjusted incidence and mortality; breast cancer mortality reduction and deaths averted; and probability of dying of breast cancer.

RESULTS

If current patterns continue, the models project that there would be about 50,100-57,400 (range across models) annual breast cancer deaths in 2025. If 90% of women were screened annually from ages 40 to 54 and biennially from ages 55 to 99 (or death), then 5100-6100 fewer deaths would occur versus current patterns, but incidence, mammograms, and false-positives would increase. If all women received the indicated systemic treatment (with no screening change), then 11,400-14,500 more deaths would be averted versus current patterns, but increased toxicity could occur. If 100% received screening plus indicated therapy, there would be 18,100-20,400 fewer deaths. Eliminating obesity yields 3300-5700 fewer breast cancer deaths versus continuation of current obesity levels.

CONCLUSIONS

Maximal reductions in breast cancer deaths could be achieved through optimizing treatment use, followed by increasing screening use and obesity prevention. Cancer 2013;119:2541–2548. © 2013 American Cancer Society.

Calorie-restricted weight loss reverses high-fat diet-induced ghrelin resistance, which contributes to rebound weight gain in a ghrelin-dependent manner

Twelve weeks of high-fat diet feeding causes ghrelin resistance in arcuate neuropeptide Y (NPY)/agouti-related protein (AgRP) neurons. In the current study, we investigated whether diet-induced weight loss could restore NPY/AgRP neuronal responsiveness to ghrelin and whether ghrelin mediates rebound weight gain after calorie-restricted (CR) weight loss. Diet-induced obese (DIO) mice were allocated to one of two dietary interventions until they reached the weight of age-matched lean controls. DIO mice received chow diet ad libitum or chow diet with 40% CR. Chow-fed and high-fat-fed mice served as controls. Both dietary interventions normalized body weight, glucose tolerance, and plasma insulin. We show that diet-induced weight loss with CR increases total plasma ghrelin, restores ghrelin sensitivity, and increases hypothalamic NPY and AgRP mRNA expression. We propose that long-term DIO creates a higher body weight set-point and that weight loss induced by CR, as seen in the high-fat CR group, provokes the brain to protect the new higher set-point. This adaptation to weight loss likely contributes to rebound weight gain by increasing peripheral ghrelin concentrations and restoring the function of ghrelin-responsive neuronal populations in the hypothalamic arcuate nucleus. Indeed, we also show that DIO ghrelin-knockout mice exhibit reduced body weight regain after CR weight loss compared with ghrelin wild-type mice, suggesting ghrelin mediates rebound weight gain after CR weight loss.

Trends in the coronary heart disease risk profile of middle-aged adults

PURPOSE

To examine recent trends in the coronary heart disease (CHD) risk profiles of the population aged 45 to 64 in the United States.

METHODS

Data from the National Health and Nutrition Examination Surveys (NHANES) from 2 time periods (1988-1994 and 2005-2008) are used to estimate the CHD risk functions derived from the Framingham Heart Study. The risk functions take account of levels of blood pressure (systolic and diastolic), total and high-density lipoprotein serum cholesterol, diabetes (doctor diagnosed or based on fasting glucose), and smoking status to estimate the 10-year risk of myocardial infarction or coronary death. We estimate the risk functions by gender, race, and age group (45-54 and 55-64).

RESULTS

The CHD risk profile of middle-aged adults has improved over time. For example, the mean 10-year risk of heart attack or CHD death among persons 55 to 64 years has declined from 7.1% to 5.2%. Declines are seen among both men and women and among non-Hispanic Blacks and non-Hispanic whites.

CONCLUSIONS

Despite increases in diabetes and obesity, the CHD risk profile of middle-aged adults improved during the period from 1988-1994 to 2005-2008.

Aging exacerbates obesity-induced oxidative stress and inflammation in perivascular adipose tissue in mice: a paracrine mechanism contributing to vascular redox dysregulation and inflammation

Obesity in the elderly individuals is increasing at alarming rates and there is evidence suggesting that elderly individuals are more vulnerable to the deleterious cardiovascular effects of obesity than younger individuals. However, the specific mechanisms through which aging and obesity interact to promote the development of cardiovascular disease remain unclear. The present study was designed to test the hypothesis that aging exacerbates obesity-induced inflammation in perivascular adipose tissue, which contributes to increased vascular oxidative stress and inflammation in a paracrine manner. To test this hypothesis, we assessed changes in the secretome, reactive oxygen species production, and macrophage infiltration in periaortic adipose tissue of young (7 month old) and aged (24 month old) high-fat diet-fed obese C57BL/6 mice. High-fat diet-induced vascular reactive oxygen species generation significantly increased in aged mice, which was associated with exacerbation of endothelial dysfunction and vascular inflammation. In young animals, high-fat diet-induced obesity promoted oxidative stress in the perivascular adipose tissue, which was associated with a marked proinflammatory shift in the profile of secreted cytokines and chemokines. Aging exacerbated obesity-induced oxidative stress and inflammation and significantly increased macrophage infiltration in periaortic adipose tissue. Using cultured arteries isolated from young control mice, we found that inflammatory factors secreted from the perivascular fat tissue of obese aged mice promote significant prooxidative and proinflammatory phenotypic alterations in the vascular wall, mimicking the aging phenotype. Overall, our findings support an important role for localized perivascular adipose tissue inflammation in exacerbation of vascular oxidative stress and inflammation in aging, an effect that likely enhances the risk for development of cardiovascular diseases from obesity in the elderly individuals.

Collaborative modeling of the impact of obesity on race-specific breast cancer incidence and mortality

Obesity affects multiple points along the breast cancer control continuum from prevention to screening and treatment, often in opposing directions. Obesity is also more prevalent in Blacks than Whites at most ages so it might contribute to observed racial disparities in mortality. We use two established simulation models from the Cancer Intervention and Surveillance Modeling Network (CISNET) to evaluate the impact of obesity on race-specific breast cancer outcomes. The models use common national data to inform parameters for the multiple US birth cohorts of Black and White women, including age- and race-specific incidence, competing mortality, mammography characteristics, and treatment effectiveness. Parameters are modified by obesity (BMI of ≥ 30 kg/m(2)) in conjunction with its age-, race-, cohort- and time-period-specific prevalence. We measure age-standardized breast cancer incidence and mortality and cases and deaths attributable to obesity. Obesity is more prevalent among Blacks than Whites until age 74; after age 74 it is more prevalent in Whites. The models estimate that the fraction of the US breast cancer cases attributable to obesity is 3.9-4.5 % (range across models) for Whites and 2.5-3.6 % for Blacks. Given the protective effects of obesity on risk among women <50 years, elimination of obesity in this age group could increase cases for both the races, but decrease cases for women ≥ 50 years. Overall, obesity accounts for 4.4-9.2 % and 3.1-8.4 % of the total number of breast cancer deaths in Whites and Blacks, respectively, across models. However, variations in obesity prevalence have no net effect on race disparities in breast cancer mortality because of the opposing effects of age on risk and patterns of age- and race-specific prevalence. Despite its modest impact on breast cancer control and race disparities, obesity remains one of the few known modifiable risks for cancer and other diseases, underlining its relevance as a public health target.

BMI trajectories among the severely obese: results from an electronic medical record population

Epidemiological studies have documented the growing prevalence of severe obesity during the past three decades. The primary goal of this study was to estimate the trajectory of BMI change over 5+ years in a cohort of subjects identified as severely obese (BMI ≥35). We conducted a retrospective cohort study among adults enrolled in Group Health (GH) in Washington State. We tracked 11,735 subjects with at least one BMI measure of 35 or greater in the calendar year 2005 through April 2010. Population averaged BMI trajectories were estimated as a quadratic function of time using a marginal regression model, adjusting for gender and baseline BMI and age. For the average male in GH, the estimated BMI trajectory exhibited a slightly inverted U-shaped pattern and a 0.17 increase in BMI over the sample period. For the average female, the BMI trajectory was slightly U-shaped with BMI decreasing 0.03 units over the sample period. We found a high degree of heterogeneity in the shape of estimated trajectories across baseline characteristics with larger 5-year BMI increases among younger subjects with a lower initial BMI. We conclude that BMI changes over 5 years among individuals classified as severely obese are generally small and consistent with studies documenting BMI changes for individuals in other lower BMI categories. Our results also suggest that once the 35 BMI threshold is reached, individuals will continue to remain severely obese, especially at younger ages.

Time trends and forecasts of body mass index from repeated cross-sectional data: a different approach

In this paper, we report a case study on a technical generalization of the Lee-Carter model, originally developed to project mortality, to forecast body mass index (BMI, kg/m2). We present the method on an annually repeated cross-sectional data set, the Dutch Health Survey, covering years between 1981 and 2008. We applied generalized additive models for location, scale and shape semi-parametric regression models to estimate the probability distribution of BMI for each combination of age, gender and year assuming that BMI follows a Box-Cox power exponential distribution. We modelled and extrapolated the distribution parameters as a function of age and calendar time using the Lee-Carter model. The projected parameters defined future BMI distributions from which we derived the prevalence of normal weight, overweight and obesity. Our analysis showed that important changes occurred not only in the location and scale of the BMI distribution but also in the shape of it. The BMI distribution became flatter and more shifted to the right. Assuming that past trends in the distribution of BMI will continue in the future, we predicted a stable or slow increase in the prevalence of overweight until 2020 among men and women. We conclude that our adaptation of the Lee-Carter model provides an insightful and flexible way of forecasting BMI and that ignoring changes in the shape of the BMI distribution would likely result in biased forecasts.

Immunological complications of obesity

Current approaches for the treatment of obesity, including diet and lifestyle changes, have not been successful in curtailing the obesity epidemic. The higher incidence of inflammation-associated chronic disease and greater susceptibility to infection in obese people represents a growing health threat. Improved understanding of the immunological processes that regulate obesity may yield new treatments for obesity-associated disorders.

A changing pattern of childhood BMI growth during the 20th century: 70 y of data from the Fels Longitudinal Study

BACKGROUND

The BMI distribution shifted upward in the United States between the 1960s and the 1990s, but little is known about secular trends in the pattern of BMI growth, particularly earlier in the century and early in childhood.

OBJECTIVE

The objective was to examine differences in BMI growth in children born in 1929-1999.

DESIGN

BMI curves from ages 2 to 18 y were produced for 855 European-American children in the Fels Longitudinal Study born in 1929-1953, 1954-1972, and 1973-1999. Age (A(min)) and BMI (BMI(min)) at adiposity rebound and age (AV(max)), BMI (BMIV(max)), and velocity (V(max)) at maximum velocity were derived; multivariable regression was used to examine whether maternal BMI, infant weight gain, and other covariates mediated the cohort effects on these traits.

RESULTS

BMI curves showed that children born in 1973-1999 had the lowest BMI values until age 5 y but had the largest values from age 8 y onward. In adjusted models, boys and girls born in 1973-1999 had a 0.15-kg/m(2) per year faster V(max) and a 1-kg/m(2) higher BMIV(max) than did children of the same sex born in 1929-1953, and girls had a 0.8-y earlier A(min) (P < 0.01). Maternal BMI and infant weight gain were associated with an obesity-prone pattern of BMI growth but did not account for the observed trends.

CONCLUSIONS

Shifts in the BMI growth rate around the time of pubertal initiation were apparent starting after 1973. The BMI growth curve did not increase monotonically over time; rather, children born during the obesity epidemic were characterized by lower BMI values before the adiposity rebound and by rapid subsequent BMI gain.

Eighty-year trends in infant weight and length growth: the Fels Longitudinal Study

OBJECTIVES

To investigate secular trends in weight and length growth from birth to 3 years of age in infants born from 1930 to 2008, and to assess whether these trends were associated with concurrent trends in pace of infant skeletal maturation and maternal body mass index.

STUDY DESIGN

Longitudinal weight and length data from 620 infants (302 girls) were analyzed with mixed effects modeling to produce growth curves and predicted anthropometry for infants born from 1930 to 1949, 1950 to 1969, 1970 to 1989, and 1990 to 2008.

RESULTS

The most pronounced differences in growth occurred in the first year of life. Infants born after 1970 were approximately 450 g heavier and 1.4 cm longer at birth, but demonstrated slower growth to 1 year of age than infants born before 1970. Growth trajectories converged after 1 year of age. There was no evidence that relative skeletal age, maternal body mass index, or maternal age together mediated associations between cohort and growth.

CONCLUSIONS

Recent birth cohorts may be characterized not only by greater birth size, but also by subsequent catch-down growth. Trends over time in human growth do not increase monotonically, and growth velocity in the first year may have declined compared with preceding generations.

Projected progression of the prevalence of obesity in Australia

Several country-specific and global projections of the future obesity prevalence have been conducted. However, these projections are obtained by extrapolating past prevalence of obesity or distributions of body weight. More accurate would be to base estimates on the most recent measures of weight change. Using measures of overweight and obesity incidence from a national, longitudinal study, we estimated the future obesity prevalence in Australian adults. Participants were adults aged ≥25 years in 2000 participating in the Australian Diabetes, Obesity, and Lifestyle (AusDiab) study (baseline 2000, follow-up 2005). In this population, approximately one-fifth of those with normal weight or overweight progressed to a higher weight category within 5 years. Between 2000 and 2025, the adult prevalence of normal weight was estimated to decrease from 40.6 to 28.1% and the prevalence of obesity to increase from 20.5 to 33.9%. By the time, those people aged 25-29 in 2000 reach 60-64 years, 22.1% will be normal weight, and 42.4% will be obese. On average, normal-weight females aged 25-29 years in 2000 will live another 56.2 years: 26.6 years with normal weight, 15.6 years with overweight, and 14.0 years with obesity. Normal-weight males aged 25-29 years in 2000 will live another 51.5 years: 21.6 years with normal weight, 21.1 years with overweight, and 8.8 years with obesity. If the rates of weight gain observed in the first 5 years of this decade are maintained, our findings suggest that normal-weight adults will constitute less than a third of the population by 2025, and the obesity prevalence will have increased by 65%.

BMI and obesity in US blood donors: a potential public health role for the blood centre

OBJECTIVE

According to the 2007-2008 National Health and Nutrition Examination Survey, the prevalence of obesity in the US population was 33·8 %; 34·3 % and 38·2 %, respectively, in middle-aged men and women. We asked whether available blood donor data could be used for obesity surveillance.

DESIGN

Cross-sectional study of BMI and obesity, defined as BMI ≥ 30·0 kg/m2. Adjusted odds ratios (aOR) were calculated with logistic regression.

SETTING

A network of six US blood centres.

SUBJECTS

Existing data on self-reported height and weight from blood donors, excluding persons deferred for very low body weight.

RESULTS

Among 1 042 817 donors between January 2007 and December 2008, the prevalence of obesity was 25·1 %; 25·7 % in men and 24·4 % in women. Obesity was associated with middle age (age 50-59 years v. <20 years: aOR = 1·92 for men and 1·81 for women), black (aOR = 1·57 for men and 2·35 for women) and Hispanic (aOR = 1·47 for men and 1·49 for women) race/ethnicity compared with white race/ethnicity, and inversely associated with higher educational attainment (college degree v. high school or lower: aOR = 0·56 for men and 0·48 for women) and double red cell donation and platelet donation.

CONCLUSIONS

Obesity is common among US blood donors, although of modestly lower prevalence than in the general population, and is associated with recognized demographic factors. Blood donors with higher BMI are specifically recruited for certain blood collection procedures. Blood centres can play a public health role in obesity surveillance and interventions.

Genome-environment interactions that modulate aging: powerful targets for drug discovery

Aging is the major biomedical challenge of this century. The percentage of elderly people, and consequently the incidence of age-related diseases such as heart disease, cancer, and neurodegenerative diseases, is projected to increase considerably in the coming decades. Findings from model organisms have revealed that aging is a surprisingly plastic process that can be manipulated by both genetic and environmental factors. Here we review a broad range of findings in model organisms, from environmental to genetic manipulations of aging, with a focus on those with underlying gene-environment interactions with potential for drug discovery and development. One well-studied dietary manipulation of aging is caloric restriction, which consists of restricting the food intake of organisms without triggering malnutrition and has been shown to retard aging in model organisms. Caloric restriction is already being used as a paradigm for developing compounds that mimic its life-extension effects and might therefore have therapeutic value. The potential for further advances in this field is immense; hundreds of genes in several pathways have recently emerged as regulators of aging and caloric restriction in model organisms. Some of these genes, such as IGF1R and FOXO3, have also been associated with human longevity in genetic association studies. The parallel emergence of network approaches offers prospects to develop multitarget drugs and combinatorial therapies. Understanding how the environment modulates aging-related genes may lead to human applications and disease therapies through diet, lifestyle, or pharmacological interventions. Unlocking the capacity to manipulate human aging would result in unprecedented health benefits.

Trend in obesity prevalence in European adult cohort populations during follow-up since 1996 and their predictions to 2015

Objective

To investigate trends in obesity prevalence in recent years and to predict the obesity prevalence in 2015 in European populations.

Methods

Data of 97 942 participants from seven cohorts involved in the European Prospective Investigation into Cancer and Nutrition (EPIC) study participating in the Diogenes project (named as “Diogenes cohort” in the following) with weight measurements at baseline and follow-up were used to predict future obesity prevalence with logistic linear and non-linear (leveling off) regression models. In addition, linear and leveling off models were fitted to the EPIC-Potsdam dataset with five weight measures during the observation period to find out which of these two models might provide the more realistic prediction.

Results

During a mean follow-up period of 6 years, the obesity prevalence in the Diogenes cohort increased from 13% to 17%. The linear prediction model predicted an overall obesity prevalence of about 30% in 2015, whereas the leveling off model predicted a prevalence of about 20%. In the EPIC-Potsdam cohort, the shape of obesity trend favors a leveling off model among men (R² = 0.98), and a linear model among women (R² = 0.99).

Conclusion

Our data show an increase in obesity prevalence since the 1990ies, and predictions by 2015 suggests a sizeable further increase in European populations. However, the estimates from the leveling off model were considerably lower.

Does obesity influence the prognosis of metastatic renal cell carcinoma in patients treated with vascular endothelial growth factor-targeted therapy?

BACKGROUND

Obesity increases the risk for renal cell carcinoma (RCC). However, it has only recently been identified as an independent positive prognostic factor for localized RCC.

OBJECTIVE

To determine whether obesity influences long-term prognosis in metastatic RCC patients receiving vascular endothelial growth factor-targeted therapy.

DESIGN, SETTING, AND PARTICIPANTS

In 116 patients with metastatic RCC who received antiangiogenic agents (sunitinib, sorafenib, axitinib, bevacizumab) in 2005-2010, we evaluated whether body mass index (BMI), a body surface area (BSA) above the European average, the visceral fat area (VFA), or s.c. fat area (SFA) were of predictive relevance.

MEASUREMENTS

BMI was categorized based on current World Health Organization definitions. BSA was stratified according to the European average for men (1.98 m(2)) and women (1.74 m(2)). VFA and SFA were dichotomized using the median of the observed distribution as the cutoff. The primary endpoints of this study were time to progression and overall survival time.

RESULTS AND LIMITATIONS

The whole population had median progression-free and overall survival times of 8.3 months and 20.5 months, respectively. In contrast to BMI and BSA, higher than average VFA and SFA levels were significant predictors of longer progression-free and overall survival times. The major limitations of this study are its retrospective design and its heterogeneous patient population.

CONCLUSION

This is the first study to identify high VFA and SFA levels as positive predictive biomarkers for patients who receive first-line antiangiogenic agents for metastatic RCC.

The impact of obesity on the rise in esophageal adenocarcinoma incidence: estimates from a disease simulation model

BACKGROUND

The United States has experienced an alarming and unexplained increase in the incidence of esophageal adenocarcinoma (EAC) since the 1970s. A concurrent increase in obesity has led some to suggest a relationship between the two trends. We explore the extent of this relationship.

METHODS

Using a previously validated disease simulation model of white males in the United States, we estimated EAC incidence 1973 to 2005 given constant obesity prevalence and low population progression rates consistent with the early 1970s. Introducing only the observed, rising obesity prevalence, we calculated the incremental incidence caused by obesity. We compared these with EAC incidence data from the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) registry to determine obesity's contribution to the rise therein. Incidences were converted to absolute numbers of cases using U.S. population data.

RESULTS

Using constant obesity prevalence, we projected a total of 30,555 EAC cases cumulatively over 1973 to 2005 and 1,151 in 2005 alone. Incorporating the observed obesity trend resulted in 35,767 cumulative EACs and 1,608 in 2005. Estimates derived from SEER data showed 111,223 cumulative and 7,173 cases in 2005. We conclude that the rise in obesity accounted for 6.5% of the increase in EAC cases that occurred from 1973 to 2005 and 7.6% in the year 2005.

CONCLUSION

Using published OR for EAC among obese individuals, we found that only a small percentage of the rise in EAC incidence is attributable to secular trends in obesity.

IMPACT

Other factors, alone and in combination, should be explored as causes of the EAC epidemic.

Health and economic burden of the projected obesity trends in the USA and the UK

Rising prevalence of obesity is a worldwide health concern because excess weight gain within populations forecasts an increased burden from several diseases, most notably cardiovascular diseases, diabetes, and cancers. In this report, we used a simulation model to project the probable health and economic consequences in the next two decades from a continued rise in obesity in two ageing populations--the USA and the UK. These trends project 65 million more obese adults in the USA and 11 million more obese adults in the UK by 2030, consequently accruing an additional 6-8·5 million cases of diabetes, 5·7-7·3 million cases of heart disease and stroke, 492,000-669,000 additional cases of cancer, and 26-55 million quality-adjusted life years forgone for USA and UK combined. The combined medical costs associated with treatment of these preventable diseases are estimated to increase by $48-66 billion/year in the USA and by £1·9-2 billion/year in the UK by 2030. Hence, effective policies to promote healthier weight also have economic benefits.

Immune function and HPA axis activity in free-ranging rhesus macaques

In mammals, the hypothalamic-pituitary-adrenal (HPA) axis and immune system play an important role in the maintenance of homeostasis. Dysregulation of either system resulting, for example, from psychosocial or reproductive stress increases susceptibility to disease and mortality risk, especially in aging individuals. In a study of free-ranging rhesus macaques, we examined how female age, reproductive state, social rank, and body condition influence (i) aspects of cytokine biology (plasma concentrations of interleukin-1 receptor antagonist (IL-1ra), IL-6 and IL-8), and (ii) HPA axis activity (plasma and fecal glucocorticoid levels). We also assessed individual differences in cytokine and hormone concentrations over time to determine their consistency and to investigate relations between these two indicators of physiological regulation and demand. Female monkeys showed marked increases in HPA axis activity during pregnancy and lactation, and increased circulating levels of IL-1ra with advancing age. Inter-individual differences in IL-1ra and IL-8 were consistent over successive years, suggesting that both are stable, trait-like characteristics. Furthermore, the concentrations of fecal glucocorticoid hormones in non-pregnant, non-lactating females were correlated with their plasma cortisol and IL-8 concentrations. Some individuals showed permanently elevated cytokine levels or HPA axis activity, or a combination of the two, suggesting chronic stress or disease. Our results enhance our understanding of within- and between-individual variation in cytokine levels and their relationship with glucocorticoid hormones in free-ranging primates. These findings can provide the basis for future research on stress and allostatic load in primates.

Characterization of age-related gene expression profiling in bone marrow and epididymal adipocytes

Background

While an increase in bone marrow adiposity is associated with age-related bone disease, the function of bone marrow adipocytes has not been studied. The aim of this study was to characterize and compare the age-related gene expression profiles in bone marrow adipocytes and epididymal adipocytes.

Results

A total of 3918 (13.7%) genes were differentially expressed in bone marrow adipocytes compared to epididymal adipocytes. Bone marrow adipocytes revealed a distinct gene profile with low expression of adipocyte-specific genes peroxisome proliferator-activated receptor gamma (PPARγ), fatty acid binding protein 4 (FABP4), perilipin (Plin1), adipsin (CFD) and high expression of genes associated with early adipocyte differentiation (CCAAT/enhancer binding protein beta (C/EBPβ), regulator of G-protein signaling 2 (RGS2). In addition, a number of genes including secreted frizzled related protein 4 (SFRP4), tumor necrosis factor α (TNFα), transforming growth factor beta 1(TGFβ1), G-protein coupled receptor 109A (GPR109A) and interleukin 6 (IL-6), that could affect adipose-derived signaling to bone are markedly increased in bone marrow adipocytes. Age had a substantial effect on genes associated with mitochondria function and inflammation in bone marrow adipocytes. Twenty seven genes were significantly changed with age in both adipocyte depots. Among these genes, IL6 and GPR109A were significantly reduced with age in both adipocyte depots.

Conclusions

Overall, gene profiling reveals a unique phenotype for primary bone marrow adipocytes characterized by low adipose-specific gene expression and high expression of inflammatory response genes. Bone marrow and epididymal adipocytes share a common pathway in response to aging in mice, but age has a greater impact on global gene expression in epididymal than in bone marrow adipocytes. Genes that are differentially expressed at greater levels in the bone marrow are highly regulated with age.

Simulation models of obesity: a review of the literature and implications for research and policy

Simulation models (SMs) combine information from a variety of sources to provide a useful tool for examining how the effects of obesity unfold over time and impact population health. SMs can aid in the understanding of the complex interaction of the drivers of diet and activity and their relation to health outcomes. As emphasized in a recently released report of the Institute or Medicine, SMs can be especially useful for considering the potential impact of an array of policies that will be required to tackle the obesity problem. The purpose of this paper is to present an overview of existing SMs for obesity. First, a background section introduces the different types of models, explains how models are constructed, shows the utility of SMs and discusses their strengths and weaknesses. Using these typologies, we then briefly review extant obesity SMs. We categorize these models according to their focus: health and economic outcomes, trends in obesity as a function of past trends, physiologically based behavioural models, environmental contributors to obesity and policy interventions. Finally, we suggest directions for future research.

Intergenerational energy balance interventions: a systematic literature review

Many nations have witnessed a dramatic increase in the prevalence of obesity and overweight across their population. Recognizing the influence of the household environment on energy balance has led many researchers to suggest that intergenerational interventions hold promise for addressing this epidemic. Yet few comprehensive reviews of intergenerational energy balance interventions have been undertaken. Our review of the literature over the past decade revealed that intergenerational intervention approaches to enhance energy balance use a broad array of designs, target populations, and theoretical models, making results difficult to compare and "best practices" challenging to identify. Additional themes include variation in how interventions incorporate the intergenerational component; an increasing acknowledgment of the importance of ecological models; variations in the location of interventions delivery; diversity in the intervention flexibility/structure, intensity, and duration; and variation in outcomes and measures used across studies. We discuss implications and future directions of intergenerational energy balance approaches.

Body fat distribution and inflammation among obese older adults with and without metabolic syndrome

The protective mechanisms by which some obese individuals escape the detrimental metabolic consequences of obesity are not understood. This study examined differences in body fat distribution and adipocytokines in obese older persons with and without metabolic syndrome. Additionally, we examined whether adipocytokines mediate the association between body fat distribution and metabolic syndrome. Data were from 729 obese men and women (BMI ≥ 30 kg/m(2)), aged 70-79 participating in the Health, Aging and Body Composition (Health ABC) study. Thirty-one percent of these obese men and women did not have metabolic syndrome. Obese persons with metabolic syndrome had significantly more abdominal visceral fat (men: P = 0.04; women: P < 0.01) and less thigh subcutaneous fat (men: P = 0.09; women: P < 0.01) than those without metabolic syndrome. Additionally, those with metabolic syndrome had significantly higher levels of interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and plasminogen activator inhibitor-1 (PAI-1) than individuals without metabolic syndrome. Per standard deviation higher in visceral fat, the likelihood of metabolic syndrome significantly increased in women (odds ratio (OR): 2.16, 95% confidence interval (CI): 1.59-2.94). In contrast, the likelihood of metabolic syndrome decreased in both men (OR: 0.56, 95% CI: 0.39-0.80) and women (OR: 0.49, 95% CI: 0.34-0.69) with each standard deviation higher in thigh subcutaneous fat. These associations were partly mediated by adipocytokines; the association between thigh subcutaneous fat and metabolic syndrome was no longer significant in men. In summary, metabolically healthy obese older persons had a more favorable fat distribution, characterized by lower visceral fat and greater thigh subcutaneous fat and a more favorable inflammatory profile compared to their metabolically unhealthy obese counterparts.

The impact of ageing and changing utilization patterns on future cardiovascular drug expenditure: a pharmacoepidemiological projection approach

PURPOSE

To develop a method for projecting the impact of ageing and changing drug utilization patterns on future drug expenditure.

METHODS

Applying nationwide registries, prescriptions of three categories of cardiovascular drugs were followed for all Danish residents from 1 January 1996 until 2006. The official Danish population forecast 2006-2015 was applied for projecting the population composition. A previously developed pharmacoepidemiological semi-Markov model was extended to apply for projection of future drug utilization. We either assumed that past trends in model parameters (incidence, discontinuation and drug user mortality) would continue during 2006-2015, or that all model parameters would remain unchanged at their values in 2005. Yearly drug expenditure per user of a particular drug was assumed to remain unchanged. Scenarios of future treatment prevalence with different drug categories were modelled by extrapolating future age- and gender-specific parameter values (treatment incidence, discontinuation and drug user mortality) from historic point estimates and their historic trend.

RESULTS

Provided a continuance of past trends, increasing utilization of ACE inhibitors, angiotensin II antagonists and statins translates into a rise in annual expenditure of 176%, mainly explained by increases in treatment incidence. Due to pharmacoepidemiological disequilibrium, unchanged model parameters would imply an increase of 64%, ageing alone 14%.

CONCLUSION

Increasing cardiovascular drug utilization may pose a substantial burden on future health care resources. However, prescribing behaviour is likely to depend on changing clinical guidelines. Despite the limited impact as cost driver, population ageing remains a challenge for future health care services.

Thiazolidinedione treatment and constitutive-PPARgamma activation induces ectopic adipogenesis and promotes age-related thymic involution

Age-related thymic involution is characterized by reduction in T cell production together with ectopic adipocyte development within the hematopoietic and thymic niches. Peroxisome proliferator-activated receptor gamma (PPARgamma) is required for adipocyte development, glucose homeostasis and is a target for several insulin-sensitizing drugs. Our prior studies showed that age-related elevation of PPARgamma expression in thymic stromal cells is associated with thymic involution. Here, using clinically relevant pharmacological and genetic manipulations in mouse models, we provide evidence that activation of PPARgamma leads to reduction in thymopoiesis. Treatment of aged mice with antihyperglycemic PPARgamma-ligand class of thiazolidinedione drug, rosiglitazone caused robust thymic expression of classical pro-adipogenic transcripts. Rosiglitazone reduced thymic cellularity, lowered the naïve T cell number and T cell receptor excision circles (TRECs) indicative of compromised thymopoiesis. To directly investigate whether PPARgamma activation induces thymic involution, we created transgenic mice with constitutive-active PPARgamma (CA-PPARg) fusion protein in cells of adipogenic lineage. Importantly, CA-PPARgamma transgene was expressed in thymus and in fibroblast-specific protein-1/S100A4 (FSP1(+)) cells, a marker of secondary mesenchymal cells. The CAPPARgamma fusion protein mimicked the liganded PPARgamma receptor and the transgenic mice displayed increased ectopic thymic adipogenesis and reduced thymopoiesis. Furthermore, the reduction in thymopoiesis in CA-PPARgamma mice was associated with higher bone marrow adiposity and lower hematopoietic stem cell progenitor pool. Consistent with lower thymic output, CAPPARgamma transgenic mice had restricted T cell receptor repertoire diversity. Collectively, our data suggest that activation of PPARgamma accelerates thymic aging and thymus-specific PPARgamma antagonist may forestall age-related decline in T cell diversity.

Transcriptional profiles of leukocyte populations provide a tool for interpreting gene expression patterns associated with high fat diet in mice

Background

Microarray experiments in mice have shown that high fat diet can lead to elevated expression of genes that are disproportionately associated with immune functions. These effects of high fat (atherogenic) diet may be due to infiltration of tissues by leukocytes in coordination with inflammatory processes.

Methodology/Principal Findings

The Novartis strain-diet-sex microarray database (GSE10493) was used to evaluate the hepatic effects of high fat diet (4 weeks) in 12 mouse strains and both genders. We develop and apply an algorithm that identifies “signature transcripts” for many different leukocyte populations (e.g., T cells, B cells, macrophages) and uses this information to derive an in silico “inflammation profile”. Inflammation profiles highlighted monocytes, macrophages and dendritic cells as key drivers of gene expression patterns associated with high fat diet in liver. In some strains (e.g., NZB/BINJ, B6), we estimate that 50–60% of transcripts elevated by high fat diet might be due to hepatic infiltration by these cell types. Interestingly, DBA mice appeared to exhibit resistance to localized hepatic inflammation associated with atherogenic diet. A common characteristic of infiltrating cell populations was elevated expression of genes encoding components of the toll-like receptor signaling pathway (e.g., Irf5 and Myd88).

Conclusions/Significance

High fat diet promotes infiltration of hepatic tissue by leukocytes, leading to elevated expression of immune-associated transcripts. The intensity of this effect is genetically controlled and sensitive to both strain and gender. The algorithm developed in this paper provides a framework for computational analysis of tissue remodeling processes and can be usefully applied to any in vivo setting in which inflammatory processes play a prominent role.

alpha-Lipoic acid increases energy expenditure by enhancing adenosine monophosphate-activated protein kinase-peroxisome proliferator-activated receptor-gamma coactivator-1alpha signaling in the skeletal muscle of aged mice

Skeletal muscle mitochondrial dysfunction is associated with aging and diabetes, which decreases respiratory capacity and increases reactive oxygen species. Lipoic acid (LA) possesses antioxidative and antidiabetic properties. Metabolic action of LA is mediated by activation of adenosine monophosphate-activated protein kinase (AMPK), a cellular energy sensor that can regulate peroxisome proliferator-activated receptor-gamma coactivator-1alpha (PGC-1alpha), a master regulator of mitochondrial biogenesis. We hypothesized that LA improves energy metabolism and mitochondrial biogenesis by enhancing AMPK-PGC-1alpha signaling in the skeletal muscle of aged mice. C57BL/6 mice (24 months old, male) were supplemented with or without alpha-LA (0.75% in drinking water) for 1 month. In addition, metabolic action and cellular signaling of LA were studied in cultured mouse myoblastoma C2C12 cells. Lipoic acid supplementation improved body composition, glucose tolerance, and energy expenditure in the aged mice. Lipoic acid increased skeletal muscle mitochondrial biogenesis with increased phosphorylation of AMPK and messenger RNA expression of PGC-1alpha and glucose transporter-4. Besides body fat mass, LA decreased lean mass and attenuated phosphorylation of mammalian target of rapamycin (mTOR) signaling in the skeletal muscle. In cultured C2C12 cells, LA increased glucose uptake and palmitate beta-oxidation, but decreased protein synthesis, which was associated with increased phosphorylation of AMPK and expression of PGC-1alpha and glucose transporter-4, and attenuated phosphorylation of mTOR and p70S6 kinase. We conclude that LA improves skeletal muscle energy metabolism in the aged mouse possibly through enhancing AMPK-PGC-1alpha-mediated mitochondrial biogenesis and function. Moreover, LA increases lean mass loss possibly by suppressing protein synthesis in the skeletal muscle by down-regulating the mTOR signaling pathway. Thus, LA may be a promising supplement for treatment of obesity and/or insulin resistance in older patients.

Alterations in skeletal muscle fatty acid handling predisposes middle-aged mice to diet-induced insulin resistance

OBJECTIVE

Although advanced age is a risk factor for type 2 diabetes, a clear understanding of the changes that occur during middle age that contribute to the development of skeletal muscle insulin resistance is currently lacking. Therefore, we sought to investigate how middle age impacts skeletal muscle fatty acid handling and to determine how this contributes to the development of diet-induced insulin resistance.

RESEARCH DESIGN AND METHODS

Whole-body and skeletal muscle insulin resistance were studied in young and middle-aged wild-type and CD36 knockout (KO) mice fed either a standard or a high-fat diet for 12 weeks. Molecular signaling pathways, intramuscular triglycerides accumulation, and targeted metabolomics of in vivo mitochondrial substrate flux were also analyzed in the skeletal muscle of mice of all ages.

RESULTS

Middle-aged mice fed a standard diet demonstrated an increase in intramuscular triglycerides without a concomitant increase in insulin resistance. However, middle-aged mice fed a high-fat diet were more susceptible to the development of insulin resistance-a condition that could be prevented by limiting skeletal muscle fatty acid transport and excessive lipid accumulation in middle-aged CD36 KO mice.

CONCLUSION

Our data provide insight into the mechanisms by which aging becomes a risk factor for the development of insulin resistance. Our data also demonstrate that limiting skeletal muscle fatty acid transport is an effective approach for delaying the development of age-associated insulin resistance and metabolic disease during exposure to a high-fat diet.

Reproductive axis function and gonadotropin microheterogeneity in a male rat model of diet-induced obesity

Obesity causes complex metabolic and endocrine changes that may lead to adverse outcomes, including hypogonadism. We herein studied the reproductive axis function in male rats under a high-fat diet and analyzed the impact of changes in glycosylation of pituitary LH on the bioactivity of this gonadotropin. Rats were fed with a diet enriched in saturated fat (20% of total calories) and euthanized on days 90 or 180 of diet. Long-term (180 days), high-fat feeding rats exhibited a metabolic profile compatible with insulin resistance and metabolic syndrome; they concomitantly showed decreased intrapituitary and serum LH concentrations, low serum testosterone levels, and elevated serum 17beta-estradiol concentrations. A fall in biological to immunological ratio of intrapituitary LH was detected in 180 days control diet-treated rats but not in high-fat-fed animals, as assessed by a homologous in vitro bioassay. Chromatofocusing of pituitary extracts yielded multiple LH charge isoforms; a trend towards decreased abundance of more basic isoforms (pH 9.99-9.0) was apparent in rats fed with the control diet for 180 days but not in those that were fed the diet enriched in saturated fat. It is concluded that long-term high-fat feeding alters the function of the pituitary-testicular axis, resulting in hypogonadotropic hypogonadism. The alterations in LH function found in these animals might be subserved by changes in hypothalamic GnRH output and/or sustained gonadotrope exposure to an altered sex steroid hormone milieu, representing a distinctly different regulatory mechanism whereby the pituitary attempts to counterbalance the effects of long-term obesity on reproductive function.

Increase in the prevalence of obesity in Switzerland 1982-2007: birth cohort analysis puts recent slowdown into perspective

Although the prevalence of obesity continues to increase in Switzerland, the latest figures suggest a slowdown in the rate of increase. In order to elucidate whether this could be the onset of a trend reversal, we analyzed cross-sectional data by birth cohort. We assessed the prevalence of overweight+ (BMI > or =25 kg/m(2)) and obesity (BMI > or =30 kg/m(2)) in six population surveys with self-reported height and weight values (Switzerland, N = 68,829, 1982-2007, men (45%) and women (55%), aged 20-84 years) by 10-year birth cohorts (from the decade 1910-1919 through to 1970-1979). We found that increases in the prevalence of overweight+ and obesity occurred mainly in the cohort born 1930 to 1939, and again in the cohorts born 1960 to 1979. The accelerated increase in the prevalence of overweight+ in the youngest birth cohort and the lower prevalence in the oldest birth cohorts suggest that the current slowdown seen in Switzerland may not herald the onset of a trend reversal. As this example shows, simple comparisons of prevalence rates over time could provide a misleading picture of actual trends. Birth cohort analysis may offer a valuable alternative.

Aging and regional differences in fat cell progenitors - a mini-review

Fat mass and fat tissue distribution change dramatically throughout life. In old age, fat becomes dysfunctional and is redistributed from subcutaneous to intra-abdominal visceral depots as well as other ectopic sites, including bone marrow, muscle and the liver. These changes are associated with increased risk of metabolic syndrome. Fat tissue is a nutrient storage, endocrine and immune organ that undergoes renewal throughout the lifespan. Preadipocytes, which account for 15-50% of cells in fat tissue, give rise to new fat cells. With aging, declines in preadipocyte proliferation and differentiation likely contribute to increased systemic exposure to lipotoxic free fatty acids. Age-related fat tissue inflammation is related to changes that occur in preadipocytes and macrophages in a fat depot-dependent manner. Fat tissue inflammation frequently leads to further reduction in adipogenesis with aging, more lipotoxicity and activation of cellular stress pathways that, in turn, exacerbate inflammatory responses of preadipocytes and immune cells, establishing self-perpetuating cycles that lead to systemic dysfunction. In this review, we will consider how inherent, age-related, depot-dependent alterations in preadipocyte function contribute to age-related fat tissue redistribution and metabolic dysfunction.

Changes in cardiovascular hospitalization and comorbidity of heart failure in the United States: findings from the National Hospital Discharge Surveys 1980-2006

OBJECTIVE

This study aimed to update the long-term trend of coronary heart disease (CHD), cerebrovascular disease (CBVD), and heart failure (HF) hospitalization rates and HF comorbidity among adults aged 65 and older in the United States.

METHODS

Data from the National Hospital Discharge Surveys between 1980 and 2006 were used. CHD, CBVD, and HF were defined using the principal (first-listed) diagnosis of disease at hospital discharge according to the ICD-9-CM code. Census estimated population data (2000) were used to estimate age and gender-specific hospitalization rates.

RESULTS

Age-adjusted CHD and CBVD hospitalization rates have significantly decreased between 1980 and 2006, with an estimated annual decrease rate of 2.24% for CHD and 1.55% for CBVD in men, and 2.36% for CHD and 1.34% for CBVD in women. However, the absolute numbers of CHD and CBVD hospitalization continued to increase partly because of the aging population. Furthermore, HF hospitalization rates have significantly increased with an estimated annual rate increase of 1.20% in men and 1.55% in women between 1980 and 2006. Of six selected co-morbidities, about 50% in men and 40% in women with HF had a coexisting disease of CHD, followed by chronic obstructive pulmonary disease, diabetes mellitus, renal failure, and pneumonia.

CONCLUSIONS

While the burden of CHD and CBVD remains the major public health problem, HF has emerged as a new challenge in cardiovascular disease control, characterized by increased trends of HF hospitalization and increased comorbidities from major diseases.