J. Josh Snodgrass

What a Drop Can Do: Dried Blood Spots as a Minimally Invasive Method for Integrating Biomarkers Into Population-Based Research

Logistical constraints associated with the collection and analysis of biological samples in community-based settings have been a significant impediment to integrative, multilevel biodemographic and biobehavioral research. However, recent methodological developments have overcome many of these constraints and have also expanded the options for incorporating biomarkers into population-based health research in international as well as domestic contexts. In particular, using dried blood spot (DBS) samples—drops of whole blood collected on filter paper from a simple finger prick— provides a minimally invasive method for collecting blood samples in nonclinical settings. After a brief discussion of biomarkers more generally, we review procedures for collecting, handling, and analyzing DBS samples. Advantages of using DBS samples—compared with venipuncture—include the relative ease and low cost of sample collection, transport, and storage. Disadvantages include requirements for assay development and validation as well as the relatively small volumes of sample. We present the results of a comprehensive literature review of published protocols for analysis of DBS samples, and we provide more detailed analysis of protocols for 45 analytes likely to be of particular relevance to population-level health research. Our objective is to provide investigators with the information they need to make informed decisions regarding the appropriateness of blood spot methods for their research interests.

Data Resource Profile: The World Health Organization Study on global AGEing and adult health (SAGE)

Population ageing is rapidly becoming a global issue and will have a major impact on health policies and programmes. The World Health Organizations Study on global AGEing and adult health (SAGE) aims to address the gap in reliable data and scientific knowledge on ageing and health in low- and middle-income countries. SAGE is a longitudinal study with nationally representative samples of persons aged 50+ years in China, Ghana, India, Mexico, Russia and South Africa, with a smaller sample of adults aged 18-49 years in each country for comparisons. Instruments are compatible with other large high-income country longitudinal ageing studies. Wave 1 was conducted during 2007-2010 and included a total of 34 124 respondents aged 50+ and 8340 aged 18-49. In four countries, a subsample consisting of 8160 respondents participated in Wave 1 and the 2002/04 World Health Survey (referred to as SAGE Wave 0). Wave 2 data collection will start in 2012/13, following up all Wave 1 respondents. Wave 3 is planned for 2014/15. SAGE is committed to the public release of study instruments, protocols and meta- and micro-data: access is provided upon completion of a Users Agreement available through WHOs SAGE website (www.who.int/healthinfo/systems/sage) and WHOs archive using the National Data Archive application (http://apps.who.int/healthinfo/systems/surveydata).

Human preferences for sexually dimorphic faces may be evolutionarily novel

Significance It is a popular assumption that certain perceptions—for example, that highly feminine women are attractive, or that masculine men are aggressive—reflect evolutionary processes operating within ancestral human populations. However, observations of these perceptions have mostly come from modern, urban populations. This study presents data on cross-cultural perceptions of facial masculinity and femininity. In contrast to expectations, we find that in less developed environments, typical “Western” perceptions are attenuated or even reversed, suggesting that Western perceptions may be relatively novel. We speculate that novel environments, which expose individuals to large numbers of unfamiliar faces, may provide novel opportunities—and motives—to discern subtle relationships between facial appearance and other traits. A large literature proposes that preferences for exaggerated sex typicality in human faces (masculinity/femininity) reflect a long evolutionary history of sexual and social selection. This proposal implies that dimorphism was important to judgments of attractiveness and personality in ancestral environments. It is difficult to evaluate, however, because most available data come from large-scale, industrialized, urban populations. Here, we report the results for 12 populations with very diverse levels of economic development. Surprisingly, preferences for exaggerated sex-specific traits are only found in the novel, highly developed environments. Similarly, perceptions that masculine males look aggressive increase strongly with development and, specifically, urbanization. These data challenge the hypothesis that facial dimorphism was an important ancestral signal of heritable mate value. One possibility is that highly developed environments provide novel opportunities to discern relationships between facial traits and behavior by exposing individuals to large numbers of unfamiliar faces, revealing patterns too subtle to detect with smaller samples.

Life History, Immune Function, and Intestinal Helminths: Trade-Offs Among Immunoglobulin E, C-Reactive Protein, and Growth in an Amazonian Population

Objectives. Infection with helminths is associated with shifts in host immunity, including increased production of immunoglobulin E (IgE) and reduced inflammation. Given limited energy budgets, these shifts may involve changes in energy allocation toward competing demands. Here we test for potential trade‐offs between growth, IgE, and the inflammatory marker C‐reactive protein (CRP).

The Influence of Basal Metabolic Rate on Blood Pressure Among Indigenous Siberians

Hypertension is an important global health issue and is currently increasing at a rapid pace in most industrializing nations. Although a number of risk factors have been linked with the development of hypertension, including obesity, high dietary sodium, and chronic psychosocial stress, these factors cannot fully explain the variation in blood pressure and hypertension rates that occurs within and between populations. The present study uses data collected on adults from three indigenous Siberian populations (Evenki, Buryat, and Yakut [Sakha]) to test the hypothesis of Luke et al. (Hypertension 43 (2004) 555-560) that basal metabolic rate (BMR) and blood pressure are positively associated independent of body size. When adjusted for body size and composition, as well as potentially confounding variables such as age, smoking status, ethnicity, and degree of urbanization, BMR was positively correlated with systolic blood pressure (SBP; P < 0.01) and pulse pressure (PP; P < 0.01); BMR showed a trend with diastolic blood pressure (DBP; P = 0.08). Thus, higher BMR is associated with higher SBP and PP; this is opposite the well-documented inverse relationship between physical activity and blood pressure. If the influence of BMR on blood pressure is confirmed, the systematically elevated BMRs of indigenous Siberians may help explain the relatively high blood pressures and hypertension rates documented among native Siberians in the post-Soviet period. These findings underscore the importance of considering the influence of biological adaptation to regional environmental conditions in structuring health changes associated with economic development and lifestyle change.

Evidence for a peak shift in a humoral response to helminths: age profiles of IgE in the Shuar of Ecuador, the Tsimane of Bolivia, and the U.S. NHANES.

Background The peak shift model predicts that the age-profile of a pathogens prevalence depends upon its transmission rate, peaking earlier in populations with higher transmission and declining as partial immunity is acquired. Helminth infections are associated with increased immunoglobulin E (IgE), which may convey partial immunity and influence the peak shift. Although studies have noted peak shifts in helminths, corresponding peak shifts in total IgE have not been investigated, nor has the age-patterning been carefully examined across populations. We test for differences in the age-patterning of IgE between two South American forager-horticulturalist populations and the United States: the Tsimane of Bolivia (n = 832), the Shuar of Ecuador (n = 289), and the U.S. NHANES (n = 8,336). We then examine the relationship between total IgE and helminth prevalences in the Tsimane. Methodology/Principal Findings Total IgE levels were assessed in serum and dried blood spots and age-patterns examined with non-linear regression models. Tsimane had the highest IgE (geometric mean  = 8,182 IU/ml), followed by Shuar (1,252 IU/ml), and NHANES (52 IU/ml). Consistent with predictions, higher population IgE was associated with steeper increases at early ages and earlier peaks: Tsimane IgE peaked at 7 years, Shuar at 10 years, and NHANES at 17 years. For Tsimane, the age-pattern was compared with fecal helminth prevalences. Overall, 57% had detectable eggs or larva, with hookworm (45.4%) and Ascaris lumbricoides (19.9%) the most prevalent. The peak in total IgE occurred around the peak in A. lumbricoides, which was associated with higher IgE in children <10, but with lower IgE in adolescents. Conclusions The age-patterning suggests a peak shift in total IgE similar to that seen in helminth infections, particularly A. lumbricoides. This age-patterning may have implications for understanding the effects of helminths on other health outcomes, such as allergy, growth, and response to childhood vaccination.

Neandertal Energetics Revisited: Insights into Population Dynamics and Life History Evolution

Paleoanthropologists are increasingly utilizing energetic models to provide insights into hominin ecology and evolution. Energy dynamics represent a key interface between an organism and its environment; how energy is extracted from limited resources and allocated to various somatic functions has consequences for survival and reproduction. Within the past few years, several teams of researchers have reconstructed Neandertal energy budgets to address issues such as foraging efficiency, population density and spatial utilization, cold tolerance, and the replacement of Neandertals by modern humans. In the present paper, we systematically reexamine Neandertal energy expenditure and intake through the lens of recent developments in contemporary human biology and nutritional science. We estimate Neandertal energy expenditure and dietary needs by using published sex-specific body mass estimates coupled with physiological information on contemporary high-latitude populations. Comparative data suggest that four important factors contribute to high energy requirements in Neandertals: 1) large body mass and high levels of muscularity; 2) exposure to severe cold stress; 3) consumption of high meat, high protein diets; and, 4) high levels of physical activity. Contemporary northern populations have systematically elevated basal metabolic rates (BMRs) compared to lower latitude groups, an apparent adaptation to chronic and severe cold stress. In addition, field and laboratory studies suggest high dietary protein is associated with substantially increased metabolic heat production. Further, activity patterns among contemporary northern populations and Neandertal post-cranial morphology suggest relatively high physical activity levels. Thus, multiple lines of evidence point to extremely high energy requirements and intakes among Neandertals. The high turnover of metabolic energy in Neandertals likely had important implications for key aspects of life history, such as physical growth rates, age at reproductive maturity, and lifespan. Consequently, a detailed exploration of Neandertal ener-getics provides insights into hominin population dynamics during the Middle to Upper Paleolithic transition.

Sex differences and aging of the vertebral column.

Morphological changes in the adult human skeleton have been recognized as useful for estimating the age at death. In the vertebral column, the development of osteophytes has been shown to be a general indicator of age, although substantial variation has been documented. The technique used for estimating age from osteophyte development is based exclusively on males and it is unknown whether patterns of osteophyte development are comparable between the sexes. This study examines sex differences in osteophyte development in the thoracic and lumbar regions of 384 individuals from the Terry Collection. Males and females in this sample show remarkably similar patterns of age-related changes in osteophyte development; however, females show greater variability in osteophyte stage for a given age. This was confirmed with age-matching a subsample of 128 individuals. Therefore, slightly larger confidence intervals should be used when assessing age from the vertebral column in females.

Associations between sleep duration, sleep quality, and cognitive test performance among older adults from six middle income countries: results from the Study on Global Ageing and Adult Health (SAGE).

BACKGROUND Alterations in sleep architecture are common among older adults. Previous studies have documented associations between sleep duration, sleep quality, and cognitive performance in older individuals, yet few studies have examined these trends using population-based samples from non-Western societies. The present cross-sectional study uses nationally representative datasets from six countries to test several hypotheses related to sleep patterns and cognitive function. METHODS Data were drawn from the first wave of the World Health Organizations study on global ageing and adult health (SAGE), a longitudinal study using samples of older adults (≥ 50 years old) in 6 middle-income countries (China, Ghana, India, Russian Federation, South Africa, and Mexico). Self-report data provided information on sleep quality and sleep duration over the previous 2 nights, and 5 cognitive tests (immediate and delayed verbal recall, forward and backward digit span, and verbal fluency) were used to create a composite z-score of cognitive performance. RESULTS Individuals with intermediate sleep durations (> 6-9 h/night) exhibited significantly higher cognitive scores than individuals with short sleep (0-6 h/night; p < 0.001) or long sleep duration (> 9 h/night; p < 0.001). Self-reported sleep quality was positively correlated with cognitive z-score (p < 0.05). Significant sex differences were observed; men generally had higher sleep quality and cognitive scores, while women reported longer sleep durations. DISCUSSION This study documented positive correlations between cognitive scores and sleep quality, and between cognitive z-scores and intermediate sleep duration. These findings are clinically important given the growing rates of dementia and aging populations globally.

Discrimination, psychosocial stress, and health among Latin American immigrants in Oregon

Chronic psychosocial stress related to discrimination has been shown to be associated with biological measures such as elevated systolic blood pressure (SBP), increased body fat, and higher fasting glucose levels. Few studies have examined these relationships in immigrant populations. The present study recruited a sample of 132 Oregon Latino immigrant adults to investigate the relationships between perceived discrimination and several health measures (blood pressure, body mass index [BMI], and fasting glucose). Results indicate that perceived discrimination stress predicted elevated SBP among men but not among women. Perceived discrimination was significantly higher among obese women than among women of normal BMI. The same pattern was not observed for men. Further, a strong trend relationship was detected: the higher womens reported discrimination stress, the higher their fasting glucose levels. Again, this pattern was not observed for men. These results suggest that chronic psychosocial stress plays an important role in disease risk among Latin American immigrants, and that male and female immigrants may have distinctive physiological responses. If confirmed, these findings may have important clinical and public health implications for chronic disease prevention among Latinos. Am. J. Hum. Biol., 2010.