Infection, inflammation, height, and longevity

Malaria: an early indicator of later disease and work level

This study investigates the effect of early-life exposure to malaria on disease and work level in old age over the past one and a half centuries. Using longitudinal lifetime records of Union Army veterans, I first estimate that exposure to a malarial environment in early life (c.1840) substantially increased the likelihood of having various chronic diseases and not working in old age (c.1900). Second, from data on US cohorts born between 1891 and 1960, I find that those exposed to a higher level of the anti-malaria campaign, which began in 1921, had lower levels of work disability in old age. Third, I seek the same implications for the modern period by linking WHO's country statistics on DALYs among older populations in 2004 to country-level malaria risk in pre-eradication era. In the paper, I discuss possible mechanisms and propose the significance of malaria eradication and early-life conditions from a long-term perspective.

Testing the evolutionary basis of the predictive adaptive response hypothesis in a preindustrial human population

BACKGROUND AND OBJECTIVES

The thrifty phenotype hypothesis proposes that late-life metabolic diseases result from mismatch between early-life and adulthood nutrition. More recently, the predictive adaptive response (PAR) hypothesis has suggested that poor early-life environmental conditions induce metabolic changes that maximize health and fitness in similarly poor adult conditions, but reduce fitness if conditions later improve. Therefore, later-life survival and reproduction should be maximized where environmental conditions during development and adulthood match, but few studies in humans have addressed the consequences of poor early conditions on fitness traits in varying later conditions.

METHODOLOGY

We tested key evolutionary predictions of the PAR hypothesis using detailed longitudinal data with several environmental parameters from a natural fertility preindustrial human population, to investigate how combinations of early- and late-life environmental conditions affected annual probabilities of survival and reproduction.

RESULTS

We found no suggestion that fitness was maximised when developmental and later-life conditions matched, but rather poor environmental conditions during development or later life and their combinations were associated with lower survival.

CONCLUSIONS AND IMPLICATIONS

Our results are more consistent with predictions of 'silver spoon' models, whereby adverse early-life conditions are detrimental to later health and fitness across all environments. Future evolutionary research on understanding metabolic disease epidemiology should focus on determining whether adaptive prediction maximizes infant survival where conditions match during development and immediately after birth, rather than drawing attention to the unlikely long-term fitness benefits of putative metabolic changes associated with poor early nutrition.

The male-female health-survival paradox and sex differences in cohort life expectancy in Utah, Denmark, and Sweden 1850-1910

PURPOSE

In Utah, the prevalence of unhealthy male risk behaviors are lower than in most other male populations, whereas women experience higher mortality risk because of higher fertility rates. Therefore, we hypothesize that the Utah sex differential in mortality would be small and less than in Sweden and Denmark.

METHODS

Life tables from Utah, Denmark, and Sweden were used to calculate cohort life expectancies for men and women born in 1850-1910.

RESULTS

The sex difference in cohort life expectancy was similar or larger in Utah when compared with Denmark and Sweden. The change over time in the sex differences in cohort life expectancy was approximately 2 years smaller for active Mormons in Utah than for other groups suggesting lifestyle as an important component for the overall change seen in cohort life expectancy. Sex differences in cohort life expectancy at the age of 50 years were similar for individuals actively affiliated with the Church of Jesus Christ of Latter-day Saints and for Denmark and Sweden.

CONCLUSIONS

The hypothesis that a smaller sex difference in cohort life expectancies in Utah would be detected in relation to Denmark and Sweden was not supported. In Utah, the male-female differences in life expectancy remain substantial pointing toward biological mechanisms or other unmeasured risk factors.

NT-proBNP, C-reactive protein and soluble uPAR in a bi-ethnic male population: the SAfrEIC study

Objective and design

This cross-sectional study aimed to investigate associations between a marker of cardiac strain, the N-terminal prohormone B-type natriuretic peptide (NT-proBNP), and inflammation as reflected by either a conventional or novel inflammatory marker in a bi-ethnic South African cohort.

Methods and subjects

We measured NT-proBNP, C-reactive protein (CRP) and plasma-soluble urokinase plasminogen activator receptor (suPAR) levels along with conventional biomarkers in black (n = 117) and white (n = 116) men.

Results

NT-proBNP, CRP and suPAR levels were higher in black compared to white men. NT-proBNP was significantly associated with both CRP (r = 0.38; p = 0.001) and suPAR (r = 0.42; p<0.001) in black men only. After full adjustment in multiple regression analyses, the above associations of NT-proBNP with CRP (β = 0.199; p = 0.018) and suPAR (β = 0.257; p<0.01) were confirmed in black men.

Conclusion

These results suggest that a low-grade inflammatory state as reflected by both a conventional and novel marker of inflammation may contribute to higher cardiovascular risk as reflected by the associations obtained with a marker of cardiac strain in black South African men.

Month of birth and mortality in Sweden: a nation-wide population-based cohort study

Background

Month of birth – an indicator for a variety of prenatal and early postnatal exposures – has been associated with life expectancy in adulthood. On the northern hemisphere, people born in the autumn live longer than those born during the spring. Only one study has followed a population longitudinally and no study has investigated the relation between month of birth and mortality risk below 50 years.

Methods and results

In this nation-wide Swedish study, we included 6,194,745 subjects, using data from population-based health and administrative registries. The relation between month of birth (January – December) and mortality risk was assessed by fitting Cox proportional hazard regression models using attained age as the underlying time scale. Analyses were made for ages >30, >30 to 50, >50 to 80 and >80 years. Month of birth was a significant predictor of mortality in the age-spans >30, >50 to 80, and >80 years. In models adjusted for gender and education for ages >30 and >50 to 80 years, the lowest mortality was seen for people born in November and the highest mortality in those born in the spring/summer, peaking in May for mortality >30 years (25‰ excess hazard ratio compared to November, [95% confidence interval = 16–34 ]) and in April for mortality >50 to 80 years (42‰ excess hazard ratio compared to November, [95% confidence interval = 30–55]). In the ages >80 years the pattern was similar but the differences in mortality between birth months were smaller. For mortality within the age-span >30 to 50 years, results were inconclusive.

Conclusion

Month of birth is associated to risk of mortality in ages above 50 years in Sweden. Further studies should aim at clarifying the mechanisms behind this association.

Marital Quality, Gender, and Markers of Inflammation in the MIDUS Cohort

Marital quality is an important factor for understanding the relationship between marriage and health. Low-quality relationships may not have the same health benefits as high-quality relationships. To understand the association between marital quality and health, we examined associations between two indicators of marital quality (marital support and marital strain) and two biomarkers of inflammation (interleukin-6 and C-reactive protein) among men and women in long-term marriages using data from the Survey of Midlife in the United States (N = 542). Lower levels of spousal support were associated with higher levels of inflammation among women but not men. Higher levels of spousal strain were weakly and inconsistently associated with higher levels of inflammation among women and men; the effects were diminished with the addition of psychosocial and behavioral covariates. These findings suggest marital quality is an important predictor of inflammation, especially among women.

Marital Quality, Gender, and Markers of Inflammation in the MIDUS Cohort

Marital quality is an important factor for understanding the relationship between marriage and health. Low-quality relationships may not have the same health benefits as high-quality relationships. To understand the association between marital quality and health, we examined associations between two indicators of marital quality (marital support and marital strain) and two biomarkers of inflammation (interleukin-6 and C-reactive protein) among men and women in long-term marriages using data from the Survey of Midlife in the United States (N = 542). Lower levels of spousal support were associated with higher levels of inflammation among women but not men. Higher levels of spousal strain were weakly and inconsistently associated with higher levels of inflammation among women and men; the effects were diminished with the addition of psychosocial and behavioral covariates. These findings suggest marital quality is an important predictor of inflammation, especially among women.

THE FRAGILITY OF THE FUTURE AND THE TUG OF THE PAST: LONGEVITY IN LATIN AMERICA AND THE CARIBBEAN

BACKGROUND

Cohorts that will attain age 60 after 2010 in the Latin American and Caribbean region (LAC) are beneficiaries of a massive mortality decline that began as early as 1930. The bulk of this decline is due to diffusion of low-cost medical technology that improved recovery rates from infectious diseases. This changes the composition of elderly cohorts in a distinct way: more among those who could experience the deleterious impact of adverse early conditions as adults survive to attain old ages.

OBJECTIVE

To compute bounds for the size of effects on old age mortality of changes in cohorts' composition by exposure to early conditions. We calculate estimates for countries in the LAC region that span the entire range of post-1950 mortality decline.

METHODS

We use counterfactual population projections to estimate bounds of changes in the composition of cohorts by exposure to early conditions. These are combined with empirical effects of adverse early conditions on adult mortality to generate estimates of foregone gains in life expectancy at age 60.

RESULTS

under somewhat conservative assumptions life expectancy at age 60 will at best increase much more slowly than in the past and at worst reach a steady state or decline. Foregone gains may be as high as 20% of projected values over a period of 30 to 50 years, the time it takes for cohorts that reaped the benefits of the secular mortality decline to become extinct.

CONCLUSIONS

Changing composition of cohorts by early exposures constitutes a powerful force that could drag down or halt short-run progress of life expectancy at older ages.

On the Role of Human Development in the Arab Spring

This essay traces the impact of human development on political change, focusing on the events of the Arab Spring. Over the past generation, the Arab world experienced rapid progress in human development outcomes, including declining child mortality, extended schooling and increasing stature of women. These development gains penetrated most Arab states and subpopulations. The pathway from human development to political mobilization rests on three interlinked propositions. First, basic human development led to a dramatic increase in population needs and expectations, creating new policy challenges and reducing public dependency on regimes. Second, human development and new information technologies created new opportunities for political protest. Finally, the collective realization of human development gains resulted in new values conducive to regime change. Each proposition builds on theories of human capital accumulation over the life course that isolate the human dimension of national development. I provide provisional support for these pathways through cross-regional comparison and evidence from specific populations and sub-populations. I highlight the need for new study designs and datasets that further test this model.

Early environments and the ecology of inflammation

Recent research has implicated inflammatory processes in the pathophysiology of a wide range of chronic degenerative diseases, although inflammation has long been recognized as a critical line of defense against infectious disease. However, current scientific understandings of the links between chronic low-grade inflammation and diseases of aging are based primarily on research in high-income nations with low levels of infectious disease and high levels of overweight/obesity. From a comparative and historical point of view, this epidemiological situation is relatively unique, and it may not capture the full range of ecological variation necessary to understand the processes that shape the development of inflammatory phenotypes. The human immune system is characterized by substantial developmental plasticity, and a comparative, developmental, ecological framework is proposed to cast light on the complex associations among early environments, regulation of inflammation, and disease. Recent studies in the Philippines and lowland Ecuador reveal low levels of chronic inflammation, despite higher burdens of infectious disease, and point to nutritional and microbial exposures in infancy as important determinants of inflammation in adulthood. By shaping the regulation of inflammation, early environments moderate responses to inflammatory stimuli later in life, with implications for the association between inflammation and chronic diseases. Attention to the eco-logics of inflammation may point to promising directions for future research, enriching our understanding of this important physiological system and informing approaches to the prevention and treatment of disease.

Early determinants of the ageing trajectory

Over the past 250 years, human life expectancy has increased dramatically and continues to do so in most countries worldwide. Genetic factors account for about one third of variation in life expectancy so that most inter-individual variation in lifespan is explained by stochastic and environmental factors. The ageing process is plastic and is driven by the accumulation of molecular damage causing the changes in cell and tissue function which characterise the ageing phenotype. Early life exposures mark the developing embryo, foetus and child with potentially profound implications for the individual's ageing trajectory. Maternal factors including age, smoking, socioeconomic status, infections, nutritional status and season of birth influence offspring life expectancy and the development of age-related diseases. Although the mechanistic processes responsible are poorly understood, many of these factors appear to affect foetal growth directly or via effects on placental development. Those born relatively small i.e. which did not achieve their genetic potential in utero, appear to be at greatest disadvantage especially if they become overweight or obese in childhood. Early life events and exposures which enhance ageing are likely to contribute to molecular damage and/or reduce the repair of such damage. Such molecular damage may produce immediate defects in cellular or tissue function that are retained into later life. In addition, there is growing evidence that early life exposures produce aberrant patterns of epigenetic marks that are sustained across the life-course and result in down-regulation of cell defence mechanisms.

Climate change and children's health--a call for research on what works to protect children

Climate change is affecting and will increasingly influence human health and wellbeing. Children are particularly vulnerable to the impact of climate change. An extensive literature review regarding the impact of climate change on children's health was conducted in April 2012 by searching electronic databases PubMed, Scopus, ProQuest, ScienceDirect, and Web of Science, as well as relevant websites, such as IPCC and WHO. Climate change affects children's health through increased air pollution, more weather-related disasters, more frequent and intense heat waves, decreased water quality and quantity, food shortage and greater exposure to toxicants. As a result, children experience greater risk of mental disorders, malnutrition, infectious diseases, allergic diseases and respiratory diseases. Mitigation measures like reducing carbon pollution emissions, and adaptation measures such as early warning systems and post-disaster counseling are strongly needed. Future health research directions should focus on: (1) identifying whether climate change impacts on children will be modified by gender, age and socioeconomic status; (2) refining outcome measures of children's vulnerability to climate change; (3) projecting children's disease burden under climate change scenarios; (4) exploring children's disease burden related to climate change in low-income countries; and (5) identifying the most cost-effective mitigation and adaptation actions from a children's health perspective.

Evolutionary medicine: its scope, interest and potential

This review is aimed at readers seeking an introductory overview, teaching courses and interested in visionary ideas. It first describes the range of topics covered by evolutionary medicine, which include human genetic variation, mismatches to modernity, reproductive medicine, degenerative disease, host-pathogen interactions and insights from comparisons with other species. It then discusses priorities for translational research, basic research and health management. Its conclusions are that evolutionary thinking should not displace other approaches to medical science, such as molecular medicine and cell and developmental biology, but that evolutionary insights can combine with and complement established approaches to reduce suffering and save lives. Because we are on the cusp of so much new research and innovative insights, it is hard to estimate how much impact evolutionary thinking will have on medicine, but it is already clear that its potential is enormous.

Educational Differences in U.S. Adult Mortality: A Cohort Perspective

We use hierarchical cross-classified random-effects models to simultaneously measure age, period, and cohort patterns of mortality risk between 1986 and 2006 for non-Hispanic white and non-Hispanic black men and women with less than a high school education, a high school education, and more than a high school education. We examine all-cause mortality risk and mortality risk from heart disease, lung cancer, and unpreventable cancers. Findings reveal that temporal reductions in black and white men's and women's mortality rates were driven entirely by cohort changes in mortality. Findings also demonstrate that disparate cohort effects between education groups widened the education gap in all-cause mortality risk and mortality risk from heart disease and lung cancer across this time period. Educational disparities in mortality risk from unpreventable cancers, however, did not change. This research uncovers widening educational differences in adult mortality and demonstrates that a cohort perspective provides valuable insights for understanding recent temporal changes in U.S. mortality risk.

The health transition and biological living standards: adult height and mortality in 20th-century Spain

This paper seeks new insights concerning the health transition in 20th century Spain by analyzing both traditional (mortality-based) and alternative (anthropometric-based) health indicators. Data were drawn from national censuses, vital and cause-of-death statistics and seven National Health Surveys dating from 1987 to 2006 (almost 100,000 subjects aged 20-79 were used to compute cohort height averages). A multivariate regression analysis was performed on infant mortality and economic/historical dummy variables. Our results agree with the general timing of the health transition process in Spain as has been described to date insofar as we document that there was a rapid improvement of sanitary and health care related factors during the second half of the 20th century reflected by a steady decline in infant mortality and increase in adult height. However, the association between adult height and infant mortality turned out to be not linear. In addition, remarkable gender differences emerged: mean height increased continuously for male cohorts born after 1940 but meaningful improvements in height among female cohorts was not attained until the late 1950s.

Use of an age-period-cohort model to reveal the impact of cigarette smoking on trends in twentieth-century adult cohort mortality in England and Wales

We use an age-period-cohort (APC) model to estimate the contribution of smoking-related mortality to cohort changes in adult mortality in Britain since 1950. We show that lung cancer and overall mortality can be satisfactorily modelled using cohort relative risk and a fixed age pattern. The results of the model suggest that smoking by itself can account for a substantial fraction of change in cohort mortality for those born around the first half of the twentieth century. In particular, smoking provides an explanation for the higher-than-average improvement in the mortality of both males and females born around 1930. Our confidence in the correctness of the results of the models is strengthened by the fact that they are very similar to those of the Peto-Lopez and Preston-Glei-Wilmoth models that estimate the contribution of smoking-related to overall mortality.

Exploring the impact of climate on human longevity

The purpose of this study was to examine the impact of physical geographic factors and climate conditions on human longevity. The centenarian rate (CR) in 2005 was computed for Japan's 47 prefectures, whose geography and climate vary greatly. Several pathways, such as excess winter mortality, land use and agricultural production, possibly linking physical and climate factors with extreme longevity, were explored. The probability of becoming a centenarian varies significantly among the Japanese prefectures. In particular, the computation of CR(70) demonstrated that the actual probability for individuals 70 years old in 1975 of becoming centenarians in 2005 was 3 times higher, on average, in Okinawa, both for males and females, than in Japan as a whole. About three quarters of the variance in CR(70) for females and half for males is explained by the physical environment and land use, even when variations in the level of socio-economic status between prefectures are controlled. Our analysis highlighted two features which might have played an important role in the longevity observed in Okinawa. First, there is virtually no winter in Okinawa. For instance, the mean winter temperature observed in 2005 was 17.2°C. Second, today, there is almost no rice production in Okinawa compared to other parts of Japan. In the past, however, production was higher in Okinawa. If we consider that long term effects of harsh winters can contribute to the mortality differential in old age and if we consider that food availability in the first part of the 20th century was mainly dependent on local production, early 20th century birth cohorts in Okinawa clearly had different experiences in terms of winter conditions and in terms of food availability compared to their counterparts in other parts of Japan. This work confirms the impact of climate conditions on human longevity, but it fails to demonstrate a strong association between longevity and mountainous regions and/or air quality.

Neighborhoods and systemic inflammation: high CRP among legal and unauthorized Brazilian migrants

We estimate cross-sectional associations of neighborhood-level disorder, socioeconomic characteristics and social capital with individual-level systemic inflammation, measured as high C-reactive protein (CRP), using Boston Metropolitan Immigrant Health & Legal Status Survey (BM-IHLSS) data-a sample of relatively young, healthy foreign-born Brazilian adults. Logistic regression analyses suggest high CRP is positively associated with neighborhood disorder and negatively related to neighborhood social capital. Although we find no significant associations between other neighborhood socioeconomic variables and high CRP; males, those who were born in an urban area and those who had been graduated from high school were less likely to have had high CRP. Unauthorized Brazilian adults, those who smoked cigarettes daily and those who had a higher body mass index were more likely to have had high CRP. Our findings suggest that investigating sociogeographic stressors and social support may be important for understanding physiological dysregulation even among relatively healthy U.S. sub-populations.

Growth hormone, inflammation and aging

Mutant animals characterized by extended longevity provide valuable tools to study the mechanisms of aging. Growth hormone and insulin-like growth factor-1 (IGF-1) constitute one of the well-established pathways involved in the regulation of aging and lifespan. Ames and Snell dwarf mice characterized by GH deficiency as well as growth hormone receptor/growth hormone binding protein knockout (GHRKO) mice characterized by GH resistance live significantly longer than genetically normal animals. During normal aging of rodents and humans there is increased insulin resistance, disruption of metabolic activities and decline of the function of the immune system. All of these age related processes promote inflammatory activity, causing long term tissue damage and systemic chronic inflammation. However, studies of long living mutants and calorie restricted animals show decreased pro-inflammatory activity with increased levels of anti-inflammatory adipokines such as adiponectin. At the same time, these animals have improved insulin signaling and carbohydrate homeostasis that relate to alterations in the secretory profile of adipose tissue including increased production and release of anti-inflammatory adipokines. This suggests that reduced inflammation promoting healthy metabolism may represent one of the major mechanisms of extended longevity in long-lived mutant mice and likely also in the human.

Biodemography of exceptional longevity: early-life and mid-life predictors of human longevity

This study explores the effects of early-life and middle-life conditions on exceptional longevity using two matched case-control studies. The first study compares 198 validated centenarians born in the United States between 1890 and 1893 to their shorter-lived siblings. Family histories of centenarians were reconstructed and exceptional longevity validated using early U.S. censuses, the Social Security Administration Death Master File, state death indexes, online genealogies, and other supplementary data resources. Siblings born to young mothers (aged less than 25 years) had significantly higher chances of living to 100 compared to siblings born to older mothers (odds ratio = 2.03, 95% CI = 1.33-3.11, p = .001). Paternal age and birth order were not associated with exceptional longevity. The second study explores whether people living to 100 years and beyond differ in physical characteristics at a young age from their shorter-lived peers. A random representative sample of 240 men who were born in 1887 and survived to age 100 was selected from the U.S. Social Security Administration database and linked to U.S. World War I civil draft registration cards collected in 1917 when these men were 30 years old. These validated centenarians were then compared to randomly selected controls who were matched by calendar year of birth, race, and place of draft registration in 1917. Results showed a negative association between "stout" body build (being in the heaviest 15 percent of the population) and survival to age 100. Having the occupation of "farmer" and a large number of children (4 or more) at age 30 increased the chances of exceptional longevity. The results of both studies demonstrate that matched case-control design is a useful approach in exploring effects of early-life conditions and middle-life characteristics on exceptional longevity.

Season of birth and exceptional longevity: comparative study of american centenarians, their siblings, and spouses

This study explores the effects of month of birth (a proxy for early-life environmental influences) on the chances of survival to age 100. Months of birth for 1,574 validated centenarians born in the United States in 1880-1895 were compared to the same information obtained for centenarians' 10,885 shorter-lived siblings and 1,083 spouses. Comparison was conducted using a within-family analysis by the method of conditional logistic regression, which allows researchers to control for unobserved shared childhood or adulthood environment and common genetic background. It was found that months of birth have significant long-lasting effect on survival to age 100: siblings born in September-November have higher odds to become centenarians compared to siblings born in March. A similar month-of-birth pattern was found for centenarian spouses. These results support the idea of early-life programming of human aging and longevity.

Vaccines for the twenty-first century society

The childhood vaccination campaigns of the twentieth century represent one of the great success stories of modern medicine. But are we yet to realize the full potential of vaccines? This article discusses the medical needs of the twenty-first century society and proposes that new vaccines will play a major part in addressing these needs.

Vaccines have been one of the major revolutions in the history of mankind and, during the twentieth century, they eliminated most of the childhood diseases that used to cause millions of deaths. In the twenty-first century, vaccines will also play a major part in safeguarding people's health. Supported by the innovations derived from new technologies, vaccines will address the new needs of a twenty-first century society characterized by increased life expectancy, emerging infections and poverty in low-income countries.

Emerging perspectives in social neuroscience and neuroeconomics of aging

This article introduces the special issue of 'Social Cognitive and Affective Neuroscience' on Aging Research, and offers a broad conceptual and methodological framework for considering advances in life course research in social neuroscience and neuroeconomics. The authors highlight key areas of inquiry where aging research is raising new insights about how to conceptualize and examine critical questions about the links between cognition, emotion and motivation in social and economic behavior, as well as challenges that need to be addressed when taking a life course perspective in these fields. They also point to several emerging approaches that hold the potential for addressing these challenges, through bridging approaches from laboratory and population-based science, bridging inquiry across life stages and expanding measurement of core psychological phenotypes.

Early life infections and onset of puberty: evidence from Hong Kong's children of 1997 birth cohort

As economic development increases, puberty occurs at younger ages, and this could contribute to an increase in the incidence of cardiovascular diseases and hormone-related cancers. The factors that determine pubertal timing are poorly understood. The growth axis that is active during puberty is active in the first 6 months of life and interacts with the immune system. The authors examined whether prior infections, proxied by number of hospital admissions for infections at different ages, were associated with age at pubertal onset (Tanner stage II) using interval-censored regression in the Children of 1997 cohort, which is a population-representative Chinese birth cohort (n = 7,527). Mediation by growth was also examined. Girls, but not boys, who were hospitalized for infections at least twice in the first 6 months of life experienced pubertal onset about 8 months later (mean = 10.3 years, time ratio = 1.08, 95% confidence interval: 1.04, 1.12) than did those without such hospitalizations (mean = 9.6 years) after adjustment for infant characteristics and socioeconomic position (sex interaction: P = 0.02). There were no such associations for infections at 6 months to ≤8 years of age. Growth did not mediate the association. Early infectious morbidity in girls may be associated with later puberty, perhaps via suppression of the gonadotropic axis. The lowering of the number of infections in early life that accompanies economic development could be an additional factor that contributes to earlier puberty.

The ‘Golden Generations’ in Historical Context

Assumptions about future mortality are more important than those for factors such as fertility, migration, disability trends or real interest rates for cost projections of the U.S. Old Age, Survivors, Disability and Health Insurance scheme. Recently, one factor has been assumed to be the key driver of future mortality in both official British population projections and actuarial ones: a ‘cohort effect’ associated with a group who were born in a period centred on the early 1930s who have been identified as having experienced particularly rapid improvements in mortality rates and are often referred to as the ‘golden generations’ or ‘golden cohorts’. The concept of ‘cohort effects’ is discussed; limitations of national-level cohort data considered; and methods for identifying such effects are reviewed. Particular attention is given to the analysis of populations which have been identified as having clear cut cohort effects; those of Britain and Sweden in the later part of the nineteenth century and early twentieth century, as well as the contemporary British population. The likely magnitude of such effects is discussed using a stylised model to assess the extent to which members of the ‘golden generations’ are especially privileged.

A population-based survey of cognitive performance in a Sicilian elderly community

BACKGROUND

The global burden of neurodegenerative diseases is increasing. Previous studies reported differences related to age, gender and socioeconomic status. We calculated the cognitive performances of a Sicilian population aged 65 years or older, by means of a door-to-door population-based survey in Bagheria city, Sicily.

METHODS

A door-to-door survey was carried out in the city of Bagheria, Sicily (prevalence day September 30, 2006). A cohort of 2,200 persons was randomly stratified, obtaining a 25% sample of the whole population. Cognitive function was assessed by Mini Mental State Examination (MMSE). Percentile distributions by age, gender, education and working activity were calculated. Regression models were used to analyze the relationship between the investigated variables and cognitive performance.

RESULTS

A total of 1,837 persons agreed to participate (1,062 women and 775 men). Distribution of MMSE showed a highly significant inverse linear trend related to the increasing age (p < 0.0001) and to the degree of education (p < 0.0001), both in men and women. We observed a significant association between higher education and a better cognitive performance (OR 6.91; CI 3.24-14.76) and an inverse association between manual kind of occupation versus not manual and a poorer cognitive status (OR 0.82; CI 0.67-0.997). Height was associated with decreased cognitive performances in women (OR = 1.03; CI = 1.01-1.05) but not in men (OR = 0.997; CI = 0.993-1.002).

CONCLUSIONS

These findings provide a feature of cognitive performances in Sicily, measured by MMSE scores in individuals aged 65 years or older.

Height of nations: a socioeconomic analysis of cohort differences and patterns among women in 54 low- to middle-income countries

Background

Adult height is a useful biological measure of long term population health and well being. We examined the cohort differences and socioeconomic patterning in adult height in low- to middle-income countries.

Methods/Findings

We analyzed cross-sectional, representative samples of 364538 women aged 25-49 years drawn from 54 Demographic and Health Surveys (DHS) conducted between 1994 and 2008. Linear multilevel regression models included year of birth, household wealth, education, and area of residence, and accounted for clustering by primary sampling units and countries. Attained height was measured using an adjustable measuring board. A yearly change in birth cohorts starting with those born in 1945 was associated with a 0.0138 cm (95% CI 0.0107, 0.0169) increase in height. Increases in heights in more recent birth year cohorts were largely concentrated in women from the richer wealth quintiles. 35 of the 54 countries experienced a decline (14) or stagnation (21) in height. The decline in heights was largely concentrated among the poorest wealth quintiles. There was a strong positive association between height and household wealth; those in two richest quintiles of household wealth were 1.988 cm (95% CI 1.886, 2.090) and 1.018 cm (95% CI 0.916, 1.120) taller, compared to those in the poorest wealth quintile. The strength of the association between wealth and height was positive (0.05 to 1.16) in 96% (52/54) countries.

Conclusions

Socioeconomic inequalities in height remain persistent. Height has stagnated or declined over the last decades in low- to middle-income countries, particularly in Africa, suggesting worsening nutritional and environmental circumstances during childhood.

Global climate change and children's health: threats and strategies for prevention

BACKGROUND

Global climate change will have multiple effects on human health. Vulnerable populations-children, the elderly, and the poor-will be disproportionately affected.

OBJECTIVE

We reviewed projected impacts of climate change on children's health, the pathways involved in these effects, and prevention strategies.

DATA SOURCES

We assessed primary studies, review articles, and organizational reports.

DATA SYNTHESIS

Climate change is increasing the global burden of disease and in the year 2000 was responsible for > 150,000 deaths worldwide. Of this disease burden, 88% fell upon children. Documented health effects include changing ranges of vector-borne diseases such as malaria and dengue; increased diarrheal and respiratory disease; increased morbidity and mortality from extreme weather; changed exposures to toxic chemicals; worsened poverty; food and physical insecurity; and threats to human habitation. Heat-related health effects for which research is emerging include diminished school performance, increased rates of pregnancy complications, and renal effects. Stark variation in these outcomes is evident by geographic region and socioeconomic status, and these impacts will exacerbate health disparities. Prevention strategies to reduce health impacts of climate change include reduction of greenhouse gas emissions and adaptation through multiple public health interventions.

CONCLUSIONS

Further quantification of the effects of climate change on children's health is needed globally and also at regional and local levels through enhanced monitoring of children's environmental health and by tracking selected indicators. Climate change preparedness strategies need to be incorporated into public health programs.

Killing Me Softly: The Fetal Origins Hypothesis

In the epidemiological literature, the fetal origins hypothesis associated with David J. Barker posits that chronic, degenerative conditions of adult health, including heart disease and type 2 diabetes, may be triggered by circumstance decades earlier, in utero nutrition in particular. Economists have expanded on this hypothesis, investigating a broader range of fetal shocks and circumstances and have found a wealth of later-life impacts on outcomes including test scores, educational attainment, and income, along with health. In the process, they have provided some of the most credible observational evidence in support of the hypothesis. The magnitude of the impacts is generally large. Thus, the fetal origins hypothesis has not only survived contact with economics, but has flourished.

Infant mortality and the health of survivors: Britain, 1910–50

The first half of the twentieth century saw rapid improvements in the health and height of British children. Average height and health can be related to infant mortality through a positive selection effect and a negative scarring effect. Examining town-level panel data on the heights of school children, no evidence is found for the selection effect, but there is some support for the scarring effect. The results suggest that the improvement in the disease environment, as reflected by the decline in infant mortality, increased average height by about half a centimetre per decade in the first half of the twentieth century.

Childhood Morbidity and Health in Early Adulthood: Life course linkages in a high morbidity context

This paper examines whether morbidity in early and later childhood is associated with health later in life. I investigate the relationship between five types of childhood morbidity and risk factors for cardiovascular disease among Guatemalan adults who experienced high levels of morbidity in childhood. The analysis is based on the Human Capital Study (2002-2004), a recent follow-up of the INCAP Longitudinal Study conducted between 1969 and 1977. I find that most types of childhood morbidity are associated with poorer adult health, independent of family background, adult socioeconomic status, and health behaviors. Higher levels of infections in childhood were associated with a low level of high density lipoprotein (HDL), and higher level of triglycerides, plasma glucose, waist circumference, and obesity (but not hypertension). These results are consistent with the literature that finds that childhood morbidity is associated with increased morbidity and mortality at older ages. However, diarrheal disease in later childhood was associated with lower levels of some risk factors, as measured by triglycerides and plasma glucose, suggesting that exposure to bacteria after infancy may be beneficial for some measures of adult health.

Long run trends in the heights of European men, 19th-20th centuries

This paper presents 5-yearly data on the height of young adult men in 15 Western European countries for birth cohorts from the middle of the 19th to the end of the 20th century. The results indicate that from the 1870s to the 1970s average height increased by around 11 cm, or more than 1cm per decade. The main finding is that for the northern and middle European groups of countries the gains in height were most rapid in the period 1911-15 to 1951-55, a period that embraced two World Wars and the Great Depression but also witnessed advances in public health and hygiene. For the southern countries growth was fastest in the period 1951-55 to 1976-80. These findings suggest that advances in height were determined not only by income and living standards but also by a variety of other socioeconomic trends.

Sex differences in the consequences of early-life exposure to epidemiological stress--a life-history approach

OBJECTIVES

Exposure to infectious disease in early life has been suggested to have a negative effect on later-life survival,possibly through the induction of inflammatory responses. Although a life-course perspective emphasizes the importance of both survival and reproduction for individual fitness, to date, no studies have investigated whether early-life exposure to infectious disease has an impact on reproduction as it has been suggested for later survival.

METHODS

To address this question, I have used family reconstitution data from a historical (18th and 19th century) human population in the Krummhörn (Germany) comparing survival and reproduction between an exposed and a non-exposed group. The exposed group comprised those exposed to a high-infectious disease load during prenatal and early postnatal development.

RESULTS

The results show a marked sex difference in the impact of early-life exposure to infectious disease. Exposed females show no effect on their life expectancy but significantly reduced fertility (number of children). For exposed males, however, the effect on survival is opponent over time: mortality is increased during childhood but decreased in late adulthood. Above that, exposed males reproduce earlier and have a smaller proportion of surviving children.

CONCLUSIONS

This study does not support former studies indicating a negative association between early-life disease load and later survival. I argue that due to differences in male and female life strategies, males in general are more vulnerable especially early in life. Hence, adverse environmental conditions may have a stronger effect on male survivability and reproductive performance.

Blood lipids, infection, and inflammatory markers in the Tsimane of Bolivia

OBJECTIVES

Little is known about blood cholesterol (blood-C) levels under conditions of infection and limited diet. This study examines blood-C and markers of infection and inflammation in the Tsimane of the Bolivian Amazon, indigenous forager farmers living in conditions that model preindustrial European populations by their short life expectancy, high load of infections and inflammation, and limited diets.

METHODS

We use multivariate models to determine the relationships between lipid levels and markers of infection and inflammation. Adult Tsimane (N = 418, age 20-84) were characterized for blood lipids, cells, and inflammatory markers in relation to individual loads of parasites and village region.

RESULTS

Most of the Tsimane (60%) carried at least one parasite species, averaging 1.3 species per person. Serum high-density lipoprotein cholesterol (HDL-C), total cholesterol (total-C), and low-density lipoprotein cholesterol (LDL-C) were below the U.S. norms and varied inversely with markers of infection and inflammation: C-reactive protein (CRP), interleukin-6 (IL-6), erythrocyte sedimentation rate (ESR), immunoglobulin (Ig) E and eosinophil count. Although no relationship of parasite load to blood-C was found, there was an association between anemia and parasite prevalence.

CONCLUSIONS

We conclude that the highly infected environment of the Tsimane is related to low levels of blood total-C, HDL-C, and LDL-C. This may suggest a potential reason why arterial disease is largely absent in the Tsimane.

Predictors of inflammation in U.S. children aged 3-16 years

BACKGROUND

Little is known about the correlates of low-grade inflammation in U.S. children.

PURPOSE

This study describes the factors associated with increased levels of C-reactive protein (CRP) in U.S. children and tests whether differences in CRP emerge in childhood because of socioeconomic factors.

METHODS

Data were analyzed in 2009 from 6004 children aged 3-16 years from the National Health and Nutrition Examination Survey, 1999-2004, a representative sample of the U.S. non-institutionalized population. Tobit regression models are used to evaluate associations between predictors, including BMI-for-age, skinfold body fat measures, chronic infections, environmental tobacco exposure, low birth weight, and sociodemographics and continuous high-sensitivity CRP in milligrams per liter.

RESULTS

CRP levels were higher in U.S. children with lower family income, and these differences were largely accounted for by differences in adiposity and recent illness. Mexican-American children had higher levels of CRP compared to both whites and blacks, but these differences were not explained by measured physical risk factors.

CONCLUSIONS

Increased adiposity is associated with higher CRP concentrations in U.S children aged 3-16 years, and both socioeconomic and racial/ethnic differences exist in systemic inflammation in U.S. children. Increased childhood obesity and low-grade inflammation may contribute to later life chronic disease risk.

Dynamic heterogeneity and life histories

Biodemography is increasingly focused on the large and persistent differences between individuals within populations in fitness components (age at death, reproductive success) and fitness-related components (health, biomarkers) in humans and other species. To study such variation we propose the use of dynamic models of observable phenotypes of individuals. Phenotypic change in turn determines variation among individuals in their fitness components over the life course. We refer to this dynamic accumulation of fitness differences as dynamic heterogeneity and illustrate it for an animal population in which longitudinal data are studied using multistate capture-mark-recapture models. Although our approach can be applied to any characteristic, for our empirical example we use reproduction as the phenotypic character to define stages. We indicate how our stage-structured model describes the nature of the variation among individual characteristics that is generated by dynamic heterogeneity. We conclude by discussing our ongoing and planned work on animals and humans. We also discuss the connections between our work and recent work on human mortality, disability and health, and life course theory.

Health trends in Sub-Saharan Africa: conflicting evidence from infant mortality rates and adult heights

We investigate trends in cohort infant mortality rates and adult heights in 39 developing countries since 1961. In most regions of the world improved nutrition, and reduced childhood exposure to disease, have lead to improvements in both infant mortality and adult stature. In Sub-Saharan Africa, however, despite declining infant mortality rates, adult heights have not increased. We argue that in Sub-Saharan Africa the decline in infant mortality may have been due to interventions that prevent infant deaths rather than improved nutrition and childhood morbidity. Despite declining infant mortality, Sub-Saharan Africa may not be experiencing increases in health human capital.

Rule-based cell systems model of aging using feedback loop motifs mediated by stress responses

Investigating the complex systems dynamics of the aging process requires integration of a broad range of cellular processes describing damage and functional decline co-existing with adaptive and protective regulatory mechanisms. We evolve an integrated generic cell network to represent the connectivity of key cellular mechanisms structured into positive and negative feedback loop motifs centrally important for aging. The conceptual network is casted into a fuzzy-logic, hybrid-intelligent framework based on interaction rules assembled from a priori knowledge. Based upon a classical homeostatic representation of cellular energy metabolism, we first demonstrate how positive-feedback loops accelerate damage and decline consistent with a vicious cycle. This model is iteratively extended towards an adaptive response model by incorporating protective negative-feedback loop circuits. Time-lapse simulations of the adaptive response model uncover how transcriptional and translational changes, mediated by stress sensors NF-κB and mTOR, counteract accumulating damage and dysfunction by modulating mitochondrial respiration, metabolic fluxes, biosynthesis, and autophagy, crucial for cellular survival. The model allows consideration of lifespan optimization scenarios with respect to fitness criteria using a sensitivity analysis. Our work establishes a novel extendable and scalable computational approach capable to connect tractable molecular mechanisms with cellular network dynamics underlying the emerging aging phenotype.

The global process of aging disturbs a broad range of cellular mechanisms in a complex fashion and is not well understood. One important goal of computational approaches in aging is to develop integrated models in terms of a unifying aging theory, predicting progression of aging phenotypes grounded on molecular mechanisms. However, current experimental data incoherently reflects many isolated processes from a large diversity of approaches, biological model systems, and species, which makes such integration a challenging task. In an attempt to close this gap, we iteratively develop a fuzzy-logic cell systems model considering the interplay of damage, metabolism, and signaling by positive and negative feedback-loop motifs using relationships drawn from literature data. Because cellular biodynamics may be considered a complex control system, this approach seems particularly suitable. Here, we demonstrate that rule-based fuzzy-logic models provide semi-quantitative predictions that enhance our understanding of complex and interlocked molecular mechanisms and their implications on the aging physiome.

Childhood nutritional deprivation and cognitive impairment among older Chinese people

Late-life cognitive impairment may have its origins in childhood. Here, we examine the associations between markers of childhood nutritional deprivation and cognitive impairment in older adults. We made use of the 2002 and 2005 waves of the Chinese Longitudinal Healthy Longevity Survey to examine these associations for persons aged 65-105 (N=15,444). Anthropometric measures (arm length, knee height) and self-reported hunger were used to measure early-life nutritional deficiencies. Cognitive impairment was measured using the Chinese version of the Mini Mental State Examination. Results from multivariate logistic regression models show that both anthropometric measures and self-report markers of early-life nutritional status were significantly associated with the odds of cognitive impairment at baseline for both men and women after controlling for age and ethnicity. Adjustments for childhood and adulthood socioeconomic status, adulthood health, and lifestyle habits had little effect on these associations except for the effect of hunger among men. Results from multinomial logistic regression models show that during the three-year follow-up period, arm length was significantly associated with the onset of cognitive impairment after controlling for various confounders in men, but not in women. Our findings suggest that early-life nutritional deprivation may contribute to cognitive impairment among older Chinese adults.

Association of anthropometric characteristics with the risk of malignant lymphoma and plasma cell myeloma in a Japanese population: a population-based cohort study

BACKGROUND

Although Asian and Western populations differ markedly in anthropometric characteristics and the incidence of malignant lymphoma and plasma cell myeloma, few studies have evaluated the associations between these variables among Asian populations.

METHODS

We conducted a large-scale, population-based prospective study in a Japanese cohort that included 45,007 men and 49,540 women ages 40 to 69 years at baseline. During an average follow-up period of 13 years, 257 cases of malignant lymphoma and 88 of plasma cell myeloma were identified. Hazard ratios (HR) and 95% confidence intervals (95% CI) were estimated with the use of a Cox regression model adjusted for potential confounders.

RESULTS

Compared with the 1st quartile, categorization in the 4th quartile for height showed a positive association with lymphoid neoplasm risk (HR, 1.38; 95% CI, 1.00-1.91), and the association was significant among men (HR, 1.72; 95% CI, 1.11-2.66). A similar trend was observed for subcategories of malignant lymphoma, plasma cell myeloma, and non-Hodgkin lymphoma, albeit the associations were weak due to the small number of subjects in each category. In contrast, weight and body mass index were not associated with risk of lymphoid neoplasm.

CONCLUSIONS

Height was positively associated with risk of lymphoid neoplasm in a Japanese population.

IMPACT

Our data suggested that early life exposure to growth-related hormones, such as insulin-like growth factors and growth hormones, or genetic factors relating to height may affect the risk of lymphoid neoplasm.

Why human lifespan is rapidly increasing: solving "longevity riddle" with "revealed-slow-aging" hypothesis

Healthy life span is rapidly increasing and human aging seems to be postponed. As recently exclaimed in Nature, these findings are so perplexing that they can be dubbed the 'longevity riddle'. To explain current increase in longevity, I discuss that certain genetic variants such as hyper-active mTOR (mTarget of Rapamycin) may increase survival early in life at the expense of accelerated aging. In other words, robustness and fast aging may be associated and slow-aging individuals died prematurely in the past. Therefore, until recently, mostly fast-aging individuals managed to survive into old age. The progress of civilization (especially 60 years ago) allowed slow-aging individuals to survive until old age, emerging as healthy centenarians now. I discuss why slow aging is manifested as postponed (healthy) aging, why the rate of deterioration is independent from aging and also entertain hypothetical use of rapamycin in different eras as well as the future of human longevity.

No consistent effects of prenatal or neonatal exposure to Spanish flu on late-life mortality in 24 developed countries

We test the effects of early life exposure to disease on later health by looking for differences in late-life mortality in cohorts born around the 1918-1919 flu pandemic using data from the Human Mortality Database for 24 countries. After controlling for age, period, and sex effects, residual mortality rates did not differ systematically for flu cohorts relative to surrounding cohorts. We calculate at most a 20-day reduction in life expectancy for flu cohorts; likely values are much smaller. Estimates of influenza incidence during the pandemic suggest that exposure was high enough for this to be a robust negative result.

Why human lifespan is rapidly increasing: solving "longevity riddle" with "revealed-slow-aging" hypothesis

Healthy life span is rapidly increasing and human aging seems to be postponed. As recently exclaimed in Nature, these findings are so perplexing that they can be dubbed the 'longevity riddle'. To explain current increase in longevity, I discuss that certain genetic variants such as hyper-active mTOR (mTarget of Rapamycin) may increase survival early in life at the expense of accelerated aging. In other words, robustness and fast aging may be associated and slow-aging individuals died prematurely in the past. Therefore, until recently, mostly fast-aging individuals managed to survive into old age. The progress of civilization (especially 60 years ago) allowed slow-aging individuals to survive until old age, emerging as healthy centenarians now. I discuss why slow aging is manifested as postponed (healthy) aging, why the rate of deterioration is independent from aging and also entertain hypothetical use of rapamycin in different eras as well as the future of human longevity.