Kevin Lewis

November 22, 2012

Human mortality improvement in evolutionary context

Oskar Burger, Annette Baudisch & James Vaupel
Proceedings of the National Academy of Sciences, 30 October 2012, Pages 18210-18214

Life expectancy is increasing in most countries and has exceeded 80 in several, as low-mortality nations continue to make progress in averting deaths. The health and economic implications of mortality reduction have been given substantial attention, but the observed malleability of human mortality has not been placed in a broad evolutionary context. We quantify the rate and amount of mortality reduction by comparing a variety of human populations to the evolved human mortality profile, here estimated as the average mortality pattern for ethnographically observed hunter-gatherers. We show that human mortality has decreased so substantially that the difference between hunter-gatherers and today's lowest mortality populations is greater than the difference between hunter-gatherers and wild chimpanzees. The bulk of this mortality reduction has occurred since 1900 and has been experienced by only about 4 of the roughly 8,000 human generations that have ever lived. Moreover, mortality improvement in humans is on par with or greater than the reductions in mortality in other species achieved by laboratory selection experiments and endocrine pathway mutations. This observed plasticity in age-specific risk of death is at odds with conventional theories of aging.


Wandering Minds and Aging Cells

Elissa Epel et al.
Clinical Psychological Science, forthcoming

Many ancient contemplative traditions believe presence of mind promotes greater longevity, a belief that is hard to test. Scientific evidence suggests that mind wandering predicts unhappiness, whereas presence in the moment predicts well-being. It is important to test whether a tendency toward mind wandering is associated with biological measures of longevity beyond self-reported measures of well-being. Telomere length has recently emerged as a proxy measure of biological aging and correlate of severe stress. We assessed the association between telomere length and tendency to be present versus tendency to mind wander in 239 healthy women. Those who reported high mind wandering had shorter telomeres, consistently across immune cell types (granulocytes, lymphocytes), than did those who reported low mind wandering, even after adjusting for stress. Telomere length varies widely between adults, and these findings suggest that presence of mind may explain some of these differences. A present attentional state may promote a healthy biochemical milieu and, in turn, cell longevity.


Detecting Suicidality From Facial Appearance

Sela Kleiman & Nicholas Rule
Social Psychological and Personality Science, forthcoming

Suicide is a pervasive problem worldwide. In this investigation, we show that individuals can perceive suicidality from facial appearance with accuracy that is significantly greater than chance guessing. Inferences of expected or obvious cues, such as how depressed a person seems, did not lead to accurate judgments. Rather, perceptions of how impulsive an individual appears differentiated suicide victims from living controls. Teasing apart various forms of impulsivity revealed that perceptions of impulsive aggression, distinct from other forms of impulsive behavior (e.g., impulsive buying), distinguished suicide victims from controls. Finally, experienced mental health clinicians did not perform significantly better than laypersons at judging suicidality. Facial appearance may therefore hold cues to suicidality, expanding what is known about the expression and perception of social cues from the face and providing new insights into the relationship between mental health and nonverbal cues.


Heightened Incidence of Depressive Symptoms in Adolescents Involved in the Arts

Laura Young, Ellen Winner & Sara Cordes
Psychology of Aesthetics, Creativity, and the Arts, forthcoming

Studies have shown a higher than average incidence of mental illness in adult artists. We asked whether an association between symptoms of affective disorders and the arts is found as early as adolescence, using a sample of 2,482 15- to 16-year-old adolescents. Teens involved in afterschool arts had higher depressive symptom scores than those not involved, and the association between arts involvement and depressive symptoms held only for those scoring above the median in working memory test scores. We consider reasons for these findings, including the possibility that shared cognitive vulnerabilities may underlie both the depressive symptoms and increased arts practice, and that cognitive resources (working memory) facilitate the adaptive use of these vulnerabilities.


Housing instability and health: Findings from the Michigan recession and recovery study

Sarah Burgard, Kristin Seefeldt & Sarah Zelner
Social Science & Medicine, December 2012, Pages 2215-2224

The recession of the late 2000s has increased interest in the consequences of housing instability. Previous research has shown poorer health among those experiencing housing instability, but extant studies generally have focused on selected populations (e.g., homeowners or renters) or studied only one type of housing instability (e.g. homelessness). Using new data from the Michigan Recession and Recovery Study, a population-based sample of working-aged adults from Southeastern Michigan, U.S.A., in late 2009-early 2010, we found that about one-third of respondents recently experienced some type of housing instability. Many, but not all, types of instability were associated with health. Even after adjustment for sociodemographic characteristics and earlier health, individuals who had moved for cost reasons in the past three years were more likely than those with no housing instability to report a recent anxiety attack, while those who experienced homelessness in the past year had a higher likelihood of reporting fair/poor self-rated health and of meeting criteria for major or minor depression. Renters behind on rental payments were more likely to meet criteria for depression, while mortgage-holders behind on their mortgage or in foreclosure had a higher likelihood of reporting fair/poor self-rated health or a recent anxiety attack. Among respondents who had ever owned a home, those who completed a foreclosure recently were more likely to report major or minor depression or an anxiety attack. However, frequent moves were not associated with poorer health, and doubling up and eviction were not associated with poorer health after adjustment for characteristics that sort people into different housing instability experiences. Our findings suggest the importance of considering multiple types of housing instability and using appropriate risk groups and comparison categories.


Stagnating Life Expectancies and Future Prospects in an Age of Uncertainty

Justin Denney et al.
Social Science Quarterly, forthcoming

Objective: This article provides a timely assessment of U.S. life expectancy given recent stalls in the growth of length of life, the continuing drop in international rankings of life expectancy for the United States, and a period of growing social and economic insecurity.

Methods: Time-series analysis is used on over 70 years of data from the Human Mortality Database to forecast future life expectancy to the year 2055.

Results: The results show limited improvements in U.S. life expectancy at birth, less than three years on average, for both men and women.

Conclusions: Even in uncertain times, it is important to look forward in preparing for the needs of future populations. The results presented here underscore the relevance of policy and health initiatives aimed at improving the nation's health and reveal important insight into possible limits to mortality improvement over the next five decades.


Stress as adaptation? A test of the adaptive boost hypothesis among Batswana men

Seamus Decker & Zachary Aggott
Evolution and Human Behavior, forthcoming

Many studies have found elevated cortisol linked to negative events ("stress") and subsequent negative outcomes, such as reduced immunity and stunted growth, leading to the conclusion that high cortisol is "bad." However, a growing number of studies have found more advantaged groups showing relatively elevated cortisol. For example, higher morning cortisol followed by a steeper diurnal decline among Caucasians compared to ethnic minorities has been interpreted as a context-specific "adaptive boost" to meet daily demands. We tested the adaptive boost hypothesis using data on socioeconomic status, depressive affect and salivary cortisol among adult men (n = 32) in Botswana. Three findings emerged: (i) depressive affect was associated with lower morning cortisol (r = - 0.43, p = 0.014); (ii) depressive affect was associated with a diurnal increase in cortisol when comparing morning and evening samples (r = 0.49, p = 0.004); and (iii) depressive affect was associated with lower income (r = - 0.55, p = 0.001). Findings are consistent with the adaptive boost hypothesis and add to a growing body of evidence that elevated cortisol is not universally bad. Hypothalamic-pituitary adrenal axis (HPAA) activity, such as cortisol, may be adaptive depending on a person's contextual circumstances. Based on our findings and those of previous studies, we develop a "person-in-context" model of the threat appraisal process. Integrated with life history theory, our model facilitates testable hypotheses about intra- and inter-individual variability in HPAA and adaptive consequences.


Prenatal Exposure to Bereavement and Type-2 Diabetes: A Danish Longitudinal Population Based Study

Jiong Li et al.
PLoS ONE, August 2012

Background: The etiology of type-2 diabetes is only partly known, and a possible role of prenatal stress in programming offspring for insulin resistance has been suggested by animal models. Previously, we found an association between prenatal stress and type-1 diabetes. Here we examine the association between prenatal exposure to maternal bereavement during preconception and pregnancy and development of type-2 diabetes in the off-spring.

Methods: We utilized data from the Danish Civil Registration System to identify singleton births in Denmark born January 1st 1979 through December 31st 2008 (N = 1,878,246), and linked them to their parents, grandparents, and siblings. We categorized children as exposed to bereavement during prenatal life if their mothers lost an elder child, husband or parent during the period from one year before conception to the child's birth. We identified 45,302 children exposed to maternal bereavement; the remaining children were included in the unexposed cohort. The outcome of interest was diagnosis of type-2 diabetes. We estimated incidence rate ratios (IRRs) from birth using log-linear poisson regression models and used person-years as the offset variable. All models were adjusted for maternal residence, income, education, marital status, sibling order, calendar year, sex, and parents' history of diabetes at the time of pregnancy.

Results: We found children exposed to bereavement during their prenatal life were more likely to have a type-2 diabetes diagnosis later in life (aIRR: 1.31, 1.01-1.69). These findings were most pronounced when bereavement was caused by death of an elder child (aIRR: 1.51, 0.94-2.44). Results also indicated the second trimester of pregnancy to be the most sensitive period of bereavement exposure (aIRR:2.08, 1.15-3.76).

Conclusions: Our data suggests that fetal exposure to maternal bereavement during preconception and the prenatal period may increase the risk for developing type-2 diabetes in childhood and young adulthood.


Understanding the Potential Long-term Physical and Mental Health Consequences of Early Experiences of Victimization

Leana Bouffard & Maria Koeppel
Justice Quarterly, forthcoming

Victimization in the USA is a substantial concern, despite a trend of decreasing crime rates. Victims of crime face a number of short-term consequences such as physical injury, fear and anxiety, and/or loss of property. Long-term consequences of victimization, however, may often be overlooked. Using the first six waves of the National Longitudinal Study of Youth, the current study examines the relationship between early experiences of victimization and long-term physical and mental health outcomes, including general health, access to and use of health care, and health risk behaviors. Results find that individuals who are victimized before the age of 12, especially those who experienced repeated bullying, are more susceptible to a number of physical and mental health issues such as negative perceptions of physical and mental health, smoking, subsequent victimization experiences, and homelessness. Public health concerns and policy implications of these findings are also discussed.


Ethnic Density Effects on Physical Morbidity, Mortality, and Health Behaviors: A Systematic Review of the Literature

Laia Bécares et al.
American Journal of Public Health, December 2012, Pages e33-e66

It has been suggested that people in racial/ethnic minority groups are healthier when they live in areas with a higher concentration of people from their own ethnic group, a so-called ethnic density effect. Ethnic density effects are still contested, and the pathways by which ethnic density operates are poorly understood. The aim of this study was to systematically review the literature examining the ethnic density effect on physical health, mortality, and health behaviors. Most studies report a null association between ethnic density and health. Protective ethnic density effects are more common than adverse associations, particularly for health behaviors and among Hispanic people. Limitations of the literature include inadequate adjustment for area deprivation and limited statistical power across ethnic density measures and study samples.


Factors underlying variable DNA methylation in a human community cohort

Lucia Lam et al.
Proceedings of the National Academy of Sciences, 16 October 2012, Pages 17253-17260

Epigenetics is emerging as an attractive mechanism to explain the persistent genomic embedding of early-life experiences. Tightly linked to chromatin, which packages DNA into chromosomes, epigenetic marks primarily serve to regulate the activity of genes. DNA methylation is the most accessible and characterized component of the many chromatin marks that constitute the epigenome, making it an ideal target for epigenetic studies in human populations. Here, using peripheral blood mononuclear cells collected from a community-based cohort stratified for early-life socioeconomic status, we measured DNA methylation in the promoter regions of more than 14,000 human genes. Using this approach, we broadly assessed and characterized epigenetic variation, identified some of the factors that sculpt the epigenome, and determined its functional relation to gene expression. We found that the leukocyte composition of peripheral blood covaried with patterns of DNA methylation at many sites, as did demographic factors, such as sex, age, and ethnicity. Furthermore, psychosocial factors, such as perceived stress, and cortisol output were associated with DNA methylation, as was early-life socioeconomic status. Interestingly, we determined that DNA methylation was strongly correlated to the ex vivo inflammatory response of peripheral blood mononuclear cells to stimulation with microbial products that engage Toll-like receptors. In contrast, our work found limited effects of DNA methylation marks on the expression of associated genes across individuals, suggesting a more complex relationship than anticipated.


Parental height in relation to offspring coronary heart disease: Examining transgenerational influences on health using the west of Scotland Midspan Family Study

Linsay Gray et al.
International Journal of Epidemiology, forthcoming

Background: Adult height is known to be inversely related to coronary heart disease (CHD) risk. We sought to investigate transgenerational influence of parental height on offspring's CHD risk.

Methods: Parents took part in a cardiorespiratory disease survey in two Scottish towns during the 1970s, in which their physical stature was measured. In 1996, their offspring were invited to participate in a similar survey, which included an electrocardiogram recording and risk factor assessment.

Results: A total of 2306 natural offspring aged 30-59 years from 1456 couples were subsequently flagged for notification of mortality and followed for CHD-related hospitalizations. Taller paternal and/or maternal height was associated with socio-economic advantage, heavier birthweight and increased high-density lipoprotein cholesterol in offspring. Increased height in fathers, but more strongly in mothers (risk ratio for 1 SD change in maternal height = 0.85; 95% confidence interval: 0.76 to 0.95), was associated with a lower risk of offspring CHD, adjusting for age, sex, other parental height and CHD risk factors.

Conclusion: There is evidence of an association between taller parental, particularly maternal, height and lower offspring CHD risk. This may reflect an influence of early maternal growth on the intrauterine environment provided for her offspring.


Big 5 personality traits and interleukin-6: Evidence for "healthy Neuroticism" in a US population sample

Nicholas Turiano et al.
Brain, Behavior, and Immunity, forthcoming

The current study investigated if the Big 5 personality traits predicted interleukin-6 (IL-6) levels in a national sample over the course of 5 years. In addition, interactions among the Big 5 were tested to provide a more accurate understanding of how personality traits may influence an inflammatory biomarker. Data included 1054 participants in the Midlife Development in the U.S. (MIDUS) biomarkers subproject. The Big 5 personality traits were assessed in 2005-2006 as part of the main MIDUS survey. Medication use, comorbid conditions, smoking behavior, alcohol use, body mass index, and serum levels of IL-6 were assessed in 2005-2009 as part of the biomarkers subproject. Linear regression analyses examined personality associations with IL-6. A significant Conscientiousness*Neuroticism interaction revealed that those high in both Conscientiousness and Neuroticism had lower circulating IL-6 levels than people with all other configurations of Conscientiousness and Neuroticism. Adjustment for health behaviors diminished the magnitude of this association but did not eliminate it, suggesting that lower comorbid conditions and obesity may partly explain the lower inflammation of those high in both Conscientiousness and Neuroticism. Our findings suggest, consistent with prior speculation, that average to higher levels of Neuroticism can in some cases be associated with health benefits - in this case when it is accompanied by high Conscientiousness. Using personality to identify those at risk may lead to greater personalization in the prevention and remediation of chronic inflammation.


Effects of Child and Adolescent Health on Educational Progress

Félice Lê, Ana Diez Roux & Hal Morgenstern
Social Science & Medicine, forthcoming

Understanding how childhood and adolescent health may affect schooling is important for understanding the socioeconomic ramifications of poor early-life health as well as the relations between schooling and adult health. Using three waves of U.S. longitudinal data with extensive covariate information on a national sample of 2,368 American children aged 5-14 at baseline, we used regression methods to investigate how patterns of general health status over a 10-year period relate to completed years of schooling at the end of follow-up. As a sensitivity analysis, we used sibling fixed effects models to help control for differences stemming from familial or community factors shared between siblings. The effect of health on years of completed schooling appeared to accumulate over time, and was more evident among children who were older at baseline. Among participants aged 5-7, 8-10, and 11-14 at baseline, average differences in years of completed schooling between participants with poor health in all 3 waves and those with good health in all 3 waves were 0.02 ([95% confidence interval] -0.31, 0.35), -0.50 (-0.88, -0.12), and -1.28 (-1.78, -0.78), respectively. Point estimates from fixed effects models were very similar. Our results document the emergence and compounding over time of health-related disparities in schooling at young ages, suggesting a vicious cycle between poor health and educational outcomes. Future research better characterizing how early-life health affects educational progress will ultimately be necessary for developing effective interventions to reduce educational and health disparities.


Education and adult cause-specific mortality - examining the impact of family factors shared by 871 367 Norwegian siblings

Øyvind Næss et al.
International Journal of Epidemiology, forthcoming

Objective: To estimate the impact family factors shared by siblings has on the association between length of education and cause-specific mortality in adulthood.

Methods: The study population (n = 871 367) was all Norwegians born 1940-59 having one or more sibling within the cohort and alive in 1990. Length of education was obtained in 1990. Follow-up of deaths was from 1991 to 2008 when participants were aged 32-68 years.

Results: Sixty-five per cent of participants had one or more siblings who had completed a different number of years of formal education. A one-category difference in education was associated with a 30% increase in the hazard rate of death by all causes among men in the cohort analysis and 23% in within siblings analysis, and in women, increases were 22% and 14%, respectively. For cardiovascular disease, increases were 36% and 25% in men and 51% and 36% in women. For lung cancer, they were 48% and 29% in men and 53% and 22% in women. External causes and alcohol-related causes in men were generally similar in both analyses.

Conclusions: This study suggests that at least some of the educational inequalities in all-cause, cardiovascular disease and lung cancer, external and alcohol-related mortality are explained by factors shared by siblings.

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