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

Exploring Patterns of Human Mortality and Aging: A Reliability Theory Viewpoint

The most important manifestation of aging is an increased risk of death with advancing age, a mortality pattern characterized by empirical regularities known as mortality laws. We highlight three significant ones: the Gompertz law, compensation effect of mortality (CEM), and late-life mortality deceleration and describe new developments in this area. It is predicted that CEM should result in declining relative variability of mortality at older ages. The quiescent phase hypothesis of negligible actuarial aging at younger adult ages is tested and refuted by analyzing mortality of the most recent birth cohorts. To comprehend the aging mechanisms, it is crucial to explain the observed empirical mortality patterns. As an illustrative example of data-directed modeling and the insights it provides, we briefly describe two different reliability models applied to human mortality patterns. The explanation of aging using a reliability theory approach aligns with evolutionary theories of aging, including idea of chronic phenoptosis. This alignment stems from their focus on elucidating the process of organismal deterioration itself, rather than addressing the reasons why organisms are not designed for perpetual existence. This article is a part of a special issue of the journal that commemorates the legacy of the eminent Russian scientist Vladimir Petrovich Skulachev (1935-2023) and his bold ideas about evolution of biological aging and phenoptosis.

Does month of birth influence colorectal cancer prognosis?

PURPOSE

The main aim of this study was to identify a possible association between month of birth of colorectal cancer (CRC) patients and overall survival (OS) or disease-free survival (DFS).

METHODS

This observational study included all consecutive adult patients diagnosed with CRC undergoing oncological surgery from January 2005 to December 2019 with a minimum follow-up of 10 years. The outcome variables were locoregional recurrence, death due to cancer progression, OS and DFS. Non-supervised learning techniques (K-means) were conducted to identify groups of months with similar oncologic outcomes. Finally, OS and DFS were analysed using Kaplan-Meier and Cox regression tests. The model was calibrated with resampling techniques and subsequently a cross-validation was performed.

RESULTS

A total of 2520 patients were included. Three birth month groups with different oncologic outcomes were obtained. Survival analysis showed between-group differences in OS (p < 0.001) and DFS (p = 0.03). The multivariable Cox proportional hazards model identified the clusters obtained as independent prognostic factors for OS (p < 0.001) and DFS (p = 0.031).

CONCLUSION

There is an association between month of birth and oncologic outcomes of CRC. Patients born in the months of January, February, June, July, October and December had better OS and DFS than those born in different months of the year.

The effect of ultraviolet radiation on the incidence and severity of major mental illness using birth month, birth year, and sunspot data

Background and objectives

The evaluation of the severity of patients afflicted with major mental illness (MMI) has been problematic because of confounding variables and genetic variability. There have been multiple studies that suggest several human diseases, especially schizophrenia, are predisposed to be born in certain months or seasons. This observation implied an epigenetic effect of sunlight, likely ultraviolet radiation (UVR), which is damaging to DNA, especially in an embryo. This paper outlines a method to evaluate the severity of schizophrenia (SZ), bipolar disorder (BPD), and schizoaffective disorder (SZ-AFF) using the month/year of birth of those affected compared to the month/year of birth of the general population (GP).

Relevance

Our previous research found that more intense UVR (equal to or greater than 90 sunspot number (SSN)) had a negative effect on the average human lifespan. Also, human birth rates vary in frequency by month of birth reflecting variables like availability of food, sunlight, and other unknown epigenetic factors. We wanted to see if the patient month of birth varied from the average birth months of the general population and if UVR has an epigenetic effect promoting these diseases.

Methods

We obtained the month and year of birth of 1,233 patients admitted over a 15-year period to Maine's largest state psychiatric hospital and counted the months of birth for each diagnosis of SZ, BPD, and SZ-AFF, and compared these results to the general population's birth months of 4,265,555 persons from U. S. Census Year 2006. The number of patients in each month was normalized to August and compared with the normalized birth months of the general population (GP). Plots of the normalized months were considered rates of change (e.g., derivatives) and their respective integrals gave domains of each mental illness relative to the GP. Normalizing the GP to unity was then related to the factor 1.28, e.g., 28% more entropy, deduced from the Sun's fractal dimension imprinted on biological organisms.

Results

The percent of patients meeting our criterion for severity: SZ = 27%; BPD = 26%; SZ-AFF = 100%.

Conclusions

High UVR intensity or a rapid increase in UVR in early gestation are likely epigenetic triggers of major mental illness. BPD is more epigenetically affected than SZ or SZ-AFF disorders. We found that 52% of 1,233 patients comprised the core function of a tertiary-care psychiatric hospital. Also, mental illness exacerbated when the median SSN doubled. This work also validates the Kraeplinian dichotomy.

What is new in this research

This paper offers a new paradigm for evaluating the severity of MMI and supports significant epigenetic effects from UVR.

Early Life Interventions Can Shape Aging

It is well documented that the environment of the developing fetus, including availability of nutrients and presence of toxins, can have major impact on adult phenotype, age-related traits and risk of chronic disease. There is also accumulating evidence that postnatal environment can impact adult characteristics related to evolutionary fitness, health, and aging. To determine whether early life hormonal interventions can alter trajectory of aging, we have examined the effects of early life growth hormone (GH) replacement therapy in Prop1^df (Ames dwarf) mice which are GH deficient and remarkably long lived. Twice-daily GH injections between the ages of two and eight weeks completely normalized ("rescued") a number of adult metabolic characteristics believed to contribute to extended longevity of these mutants. Importantly, longevity of Ames dwarf mice was reduced by early life GH treatment. This was associated with histone H3 modifications. We conclude that the trajectory of mammalian aging can be modified by early life interventions. Mechanistic links among interventions during postnatal development, adult metabolic characteristics, aging, and longevity, apparently involve epigenetic phenomena.

Season of Birth and Cardiovascular Mortality in Atrial Fibrillation: A Population-Based Cohort Study

Background: The fetal origins hypothesis have associated early life exposures with the development of adverse health outcomes in adulthood. Season of birth has been shown to be associated with overall and cardiovascular mortality. Methods: We performed a retrospective database study to explore the association between season of birth and mortality in patients with atrial fibrillation. Results: A total of 8962 patients with AF were identified in the database with 1253 deaths recorded. AF patients born in spring and summer had a higher mortality rate when compared to those born in autumn and winter (hazard ratio (HR) 1.13, 95% confidence interval (CI) 1.01–1.26, p = 0.03). This effect was consistent in the male subgroup (HR 1.25, 95% CI 1.03–1.51, p = 0.02 for males born in spring; HR 1.24, 95% CI 1.03–1.51, p = 0.03 for males born in summer when compared to winter as the reference) but not in females (HR 1.02, 95% CI 0.79–1.31, p = 0.88 for females born in spring; HR 1.11, 95% CI 0.87–1.42, p = 0.39 for females born in summer when compared to winter as the reference). Results persisted after adjustment for baseline characteristics and clinical risk profile. A similar pattern was observed with cardiovascular mortality. Conclusion: Birth in spring or summer is associated with a higher risk of cardiovascular mortality in male AF patients, but not in females. This could be related to the underlying differences in rates of major adverse clinical events between genders. Further studies should aim at clarifying the mechanisms behind this association, which may help us understand the higher level of risk in female patients with AF.

Researching 100 t cows: An innovative approach to identify intrinsic cows factors associated with a high lifetime milk production

Longevity is an important trait both from an economic and social perspective. Modern dairy cows are criticized for their short productive lifespan: only a minority of animals survives to a fourth lactation, implying that most cows are culled before reaching their maximal potential. In contrast, the population of 100 t cows (HT), reaching the threshold of 100,000 kg lifetime milk yield, is growing rapidly. As these cows combine a long lifespan with high functionality, a better understanding of their intrinsic characteristics might help us to improve the overall lifespan and lifetime production in dairy cows. The aim of the present research was to compare HT with their less-producing herd mates in order to identify intrinsic cow factors associated with longevity and high lifetime production. Therefore, we matched 26,248 HT with 691,597 herd mates, born in the same year in the same herd. Data were provided by Coöperatie rundveeverbetering (CRV) and contained birth dates, calving dates, milk yield and dam information. In addition, scores for conformation traits based on classifications in the first lactation and breeding values (for milk yield, fertility, udder health and claw health) were provided. Multivariable conditional logistic regression models were built to identify factors associated with reaching a lifetime milk yield of 100,000 kg. Results revealed cows born in September and born out of heifers to have the highest odds to become a HT. When cows received a score ≥ 83 (population average 80) for udder and feet & legs conformation, they had higher odds of reaching the 100,000 kg threshold. While a greater body condition and larger rump angle increased the odds of becoming a HT, this was decreased in cows with a large body depth. Finally, breeding values for milk yield, fertility, udder health and claw health were positively associated with the likelihood of reaching a lifetime milk yield of 100,000 kg. In conclusion, to increase lifetime milk yield in dairy herds, farmers should select heifers with high scores for conformation traits like udder and feet & legs and high breeding values for milk yield, fertility and udder health. Furthermore, our data suggest that being born in September out of a heifer potentially contributes to reaching a high lifetime milk yield.

Born in winter or spring more susceptible to all-cause and cardiovascular disease death in rural areas of China: results from a 11.9-year follow-up study

There has been no evidence on the effects of birth season and birth month on mortality in China. We aimed to explore the association between birth season, birth month and all-cause and cardiovascular disease (CVD) death. A population-based sample of 21,338 Chinese rural participants aged ≥35 years at baseline was included in our analysis. Age and multivariable adjusted Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (95% CIs) for the relationship between astronomical birth season (autumn as the reference), birth month (November as the reference), and all-cause and CVD mortality. During a median follow-up period of 11.9 years, 2,207 people died from all-cause and 1,214 people were attributed to CVD death. In multivariable adjusted analyses, for all-cause death, spring and winter had HRs (95% CIs) of 1.134 (1.005–1.280) and 1.162 (1.038–1.301), respectively; January, March, May, and August had HRs (95% CIs) of 1.249 (1.027–1.518), 1.234 (1.008–1.512), 1.276 (1.037–1.571), and 1.232 (1.003–1.513), respectively. For CVD death, spring and winter with HRs (95% CIs) of mortality were 1.232 (1.048–1.449) and 1.174 (1.007–1.369), respectively; March with HR (95% CI) of mortality were 1.343 (1.030–1.750) (all P < 0.05). Our study indicated that people born in the winter or spring were significantly associated with all-cause and cardiovascular disease mortality in rural areas of China.

Season-of-birth phenomenon in health and longevity: epidemiologic evidence and mechanistic considerations

In many human populations, especially those living in regions with pronounced climatic differences between seasons, the most sensitive (prenatal and neonatal) developmental stages occur in contrasting conditions depending on the season of conception. The difference in prenatal and postnatal environments may be a factor significantly affecting human development and risk for later life chronic diseases. Factors potentially contributing to this kind of developmental programming include nutrition, outdoor temperature, infectious exposures, duration of sunlight, vitamin D synthesis, etc. Month of birth is commonly used as a proxy for exposures which vary seasonally around the perinatal period. Season-of-birth patterns have been identified for many chronic health outcomes. In this review, the research evidence for the seasonality of birth in adult-life disorders is provided and potential mechanisms underlying the phenomenon of early life seasonal programming of chronic disease and longevity are discussed.

Birth month, birth season, and overall and cardiovascular disease mortality in US women: prospective cohort study

OBJECTIVES

To evaluate the associations between birth month, birth season, and overall and cardiovascular disease mortality, and to examine the role of familial and socioeconomic factors in these associations.

DESIGN

Prospective cohort study.

SETTING

Nurses' Health Study, established in 1976, an ongoing prospective cohort study in the United States.

PARTICIPANTS

Female registered nurses who reported information on date of birth at study enrolment (n=116 911, 1976-2014, followed for 38 years).

EXPOSURE

Birth month and astronomical birth season (based on solstices and equinoxes as boundaries of the season categories).

MAIN OUTCOME MEASURES

Age and various multivariable adjusted hazard ratios and 95% confidence intervals for the association between birth months (using November as the reference), astronomical birth season (using autumn as the reference), and overall and cardiovascular disease specific mortality were assessed using Cox proportional hazards models.

RESULTS

Among study participants, 43 248 overall deaths were documented during 4 136 364 person years of follow-up since enrolment, including 8360 cardiovascular disease related deaths. In fully adjusted multivariable analyses, no significant association was observed between birth month, birth season, and overall mortality. Compared with women born in November, increased cardiovascular disease mortality was observed among those born from March to July (hazard ratio for March, 1.09, 95% confidence interval 0.98 to 1.21; April, 1.12, 1.00 to 1.24; May, 1.08, 0.98 to 1.20; June, 1.07, 0.96 to 1.19; and July 1.08, 0.98 to 1.20). Those born in April had the highest cardiovascular disease mortality, and those born in December had the lowest (December, 0.95, 0.85 to 1.06). The relative difference between the lowest and highest risk month was 17.89%. Women born in spring (1.10, 1.04 to 1.17) and summer (1.09, 1.03 to 1.16) had a higher cardiovascular disease mortality than women born in the autumn. Adjustment for familial and socioeconomic factors did not change these results. The relative difference between the lowest and highest risk season was 10.00%.

CONCLUSION

Participants born in the spring and summer (especially those born in March-July) had a slight but significant increase in cardiovascular disease specific mortality. However, no seasonal birth month effect was observed among women for overall mortality. Familial and socioeconomic factors did not appear to alter these associations. Further studies are required to confirm these findings and reveal mechanisms of these seasonal birth month effects in cardiovascular disease mortality.

Multifactorial analysis of the stochastic epigenetic variability in cord blood confirmed an impact of common behavioral and environmental factors but not of in vitro conception

Background

An increased incidence of imprint-associated disorders has been reported in babies born from assisted reproductive technology (ART). However, previous studies supporting an association between ART and an altered DNA methylation status of the conceived babies have been often conducted on a limited number of methylation sites and without correction for critical potential confounders. Moreover, all the previous studies focused on the identification of methylation changes shared among subjects while an evaluation of stochastic differences has never been conducted. This study aims to evaluate the effect of ART and other common behavioral or environmental factors associated with pregnancy on stochastic epigenetic variability using a multivariate approach.

Results

DNA methylation levels of cord blood from 23 in vitro and 41 naturally conceived children were analyzed using the Infinium HumanMethylation450 BeadChips. After multiple testing correction, no statistically significant difference emerged in the number of cord blood stochastic epigenetic variations or in the methylation levels between in vitro- and in vivo-conceived babies. Conversely, four multiple factor analysis dimensions summarizing common phenotypic, behavioral, or environmental factors (cord blood cell composition, pre or post conception supplementation of folates, birth percentiles, gestational age, cesarean section, pre-gestational mother’s weight, parents’ BMI and obesity status, presence of adverse pregnancy outcomes, mother’s smoking status, and season of birth) were significantly associated with stochastic epigenetic variability. The stochastic epigenetic variation analysis allowed the identification of a rare imprinting defect in the locus GNAS in one of the babies belonging to the control population, which would not have emerged using a classical case-control association analysis.

Conclusions

We confirmed the effect of several common behavioral or environmental factors on the epigenome of newborns and described for the first time an epigenetic effect related to season of birth. Children born after ART did not appear to have an increased risk of genome-wide changes in DNA methylation either at specific loci or randomly scattered throughout the genome. The inability to identify differences between cases and controls suggests that the number of stochastic epigenetic variations potentially induced by ART was not greater than that naturally produced in response to maternal behavior or other common environmental factors.

Electronic supplementary material

The online version of this article (10.1186/s13148-018-0510-3) contains supplementary material, which is available to authorized users.

Developmental Origins of Health Span and Life Span: A Mini-Review

BACKGROUND

A vast body of research has demonstrated that disease susceptibility and offspring health can be influenced by perinatal factors, which include both paternal and maternal behavior and environment. Offspring disease risk has the potential to affect the health span and life span of offspring.

KEY FINDINGS

Various maternal factors, such as environmental toxicant exposure, diet, stress, exercise, age at conception, and longevity have the potential to influence age-associated diseases such as cardiovascular disease, obesity, diabetes, and cancer risk in offspring. Paternal factors such as diet, age at conception, and longevity can potentially impact offspring health span and life span-reducing traits as well.

PRACTICAL IMPLICATIONS

Continued research could go a long way toward defining mechanisms of the developmental origins of life span and health span, and eventually establishing regimens to avoid negative developmental influences and to encourage positive interventions to potentially increase life span and improve health span in offspring.

Adverse Childhood Experiences among a Community of Resilient Centenarians and Seniors: Implications for a Chronic Disease Prevention Framework

CONTEXT

Research has linked adverse childhood experiences (ACEs) with chronic disease in adults and diminished life span. Adverse biological embedding of ACEs potentially occurs through inflammatory mechanisms; inflammatory marker alterations are identified as candidate biomarkers for mediating health consequences. Lifestyle practices of residents of California's Loma Linda Blue Zone, one of five worldwide longevity hotspots, may provide insight into inflammation remediation and chronic disease prevention. Little research has been done on centenarians' early-life experiences or on ACEs in a longevity community.

OBJECTIVE

To interview centenarians and seniors in this region regarding their childhood experiences to inform chronic disease prevention frameworks.

DESIGN

Qualitative study of Loma Linda Blue Zone community members. Childhood exposures and practices were assessed using focus groups and semistructured key informant interviews, with open-ended questions on general hardships and ACEs and supplemented with lifestyle and resiliency factor questions. Data were audiorecorded and transcribed. Integrative grounded theory methods guided coding and theming.

MAIN OUTCOME MEASURES

Exposure to ACEs and practice of resiliency factors.

RESULTS

Participants (7 centenarians and 29 seniors) reported exposure to multiple ACEs (domains: Economic deprivation, family dysfunction, and community violence). Community members reported practicing resiliency factors, each with anti-inflammatory properties suggesting mitigation of ACE-related toxic stress.

CONCLUSION

This is one of the first studies of its kind to identify a community of resilient members despite their tremendous burden of ACEs. Embedding the identified resiliency factors into chronic disease prevention frameworks has potential for mitigating systemic inflammation, alleviating chronic disease burden, and promoting a culture of health.

Relationship between patients' month of birth and the prevalence of chronic diseases

BACKGROUND AND OBJECTIVES

Patients' month of birth can reflect exposure to certain factors during pregnancy and the first few months of life, which could influence the onset of chronic diseases during adulthood. The aim of this study is to evaluate the association between a patient's month of birth and the presence of chronic diseases in the Spanish population, by analysing the National Health Survey for the year 2006.

PATIENTS AND METHODS

We measured the association between 27 common chronic diseases and the month of birth, estimating the odds ratios and confidence intervals at 95%, using multivariate logistical models and adjusting the results for month of birth and potentially confounding variables.

RESULTS

The sample population was made up of a total of 29,478 individuals, representing approximately 44.7 million Spanish residents on 1 January 2007. Significant associations were found between the month of birth and several chronic diseases. There is a gender-differentiated risk pattern of developing chronic diseases according to the month of birth, with more significant associations and of greater magnitude being detected among men compared to women.

CONCLUSIONS

The associations detected might reflect early exposure to environmental factors in the uterus and during the first few months of life. More specific studies are required to gain a more in-depth understanding of these associations.

Growing Up on an Appalachian Farm: A Centenarian Perspective

Background Research on centenarians to date has focused on areas with a high population of centenarians. However, there is limited literature on centenarians' perspectives about growing up on farms from the heartland of Appalachia in Eastern Tennessee. Purpose This qualitative descriptive study was designed to characterize the role of a farming childhood by exploring the viewpoints of community-dwelling centenarians who grew up on farms in south central Appalachia. Methods A qualitative descriptive design was used with a convenience sample ( n = 16). Cognitive status was determined with the Short Portable Mental Status Questionnaire. Demographic data were collected. Interviews were transcribed and analyzed with the Neuendorf method of content analysis. Results Main emerging themes were the farm, the family, and the environment. Conclusion The farm was at the center of these centenarians' childhood, influencing their family, community relations, and social interactions, which provided lessons that they utilized throughout their long lives.

Life History and Risk of Death after 50: A Survival Analysis for Europe

Dans notre étude nous avons examiné l’influence des événements du passé des individus sur le risque de décès des Européens âgés de plus de 50 ans, en contrôlant autres variables pertinentes. Notre analyse était basée sur les données d’entretiens biographiques rétrospectifs, les données d’entretiens réguliers au suivi longitudinal et celles d’entretiens de fin de vie de l’Enquête européenne SHARE sur la santé, le vieillissement et la retraite en Europe. En particulier, nous relevons l’état de santé auto-déclaré pendant l’enfance; les périodes de pauvreté, de faim et de mauvaise santé éprouvées dans le passé; et aussi l’histoire des soins de santé, y compris les soins dentaires, les analyses de sang et les mesures de pression artérielle. Ces informations, avec l’age, le sexe, l’état de santé subjectif et objectif, et d’autres facteurs socio-démographiques, permettent d’expliquer le risque de décès. L’analyse de survie, en contrôlant des variables pertinentes, montre que les événements du passé ont un impact significatif sur le risque de décès des Européens âgés de plus de 50 ans.

Predictors of Exceptional Longevity: Effects of Early-Life and Midlife Conditions, and Familial Longevity

Knowledge of strong predictors of mortality and longevity is very important for actuarial science and practice. Earlier studies found that parental characteristics as well as early-life conditions and midlife environment play a significant role in survival to advanced ages. However, little is known about the simultaneous effects of these three factors on longevity. This ongoing study attempts to fill this gap by comparing centenarians born in the United States in 1890-1891 with peers born in the same years who died at age 65. The records for centenarians and controls were taken from computerized family histories, which were then linked to 1900 and 1930 U.S. censuses. As a result of this linkage procedure, 765 records of confirmed centenarians and 783 records of controls were obtained. Analysis with multivariate logistic regression found the existence of both general and gender-specific predictors of human longevity. General predictors common for men and women are paternal and maternal longevity. Gender-specific predictors of male longevity are occupation as a farmer at age 40, Northeastern region of birth in the United States, and birth in the second half of year. A gender-specific predictor of female longevity is the availability of radio in the household according to the 1930 U.S. census. Given the importance of familial longevity as an independent predictor of survival to advanced ages, we conducted a comparative study of biological and nonbiological relatives of centenarians using a larger sample of 1,945 validated U.S. centenarians born in 1880-1895. We found that male gender of centenarian has a significant positive effect on survival of adult male relatives (brothers and fathers) but not female blood relatives. Life span of centenarian siblings-in-law is lower compared to life span of centenarian siblings and does not depend on centenarian gender. Wives of male centenarians (who share lifestyle and living conditions) have a significantly better survival compared to wives of centenarians' brothers. This finding demonstrates an important role of shared familial environment and lifestyle in human longevity. The results of this study suggest that familial background, some early-life conditions and midlife characteristics play an important role in longevity.

New Developments in the Biodemography of Aging and Longevity

Biodemography is a promising scientific approach based on using demographic data and methods for getting insights into biological mechanisms of observed processes. Recently, new important developments have happened in biodemographic studies of aging and longevity that call into question conventional aging theories and open up novel research directions. Recent studies found that the exponential increase of the mortality risk with age (the famous Gompertz law) continues even at extreme old ages in humans, rats, and mice, thus challenging traditional views about old-age mortality deceleration, mortality leveling-off, and late-life mortality plateaus. This new finding represents a challenge to many aging theories, including the evolutionary theory that explains senescence by a declining force of natural selection with age. Innovative ideas are needed to explain why exactly the same exponential pattern of mortality growth is observed not only at reproductive ages, but also at very-old postreproductive ages (up to 106 years), long after the force of natural selection becomes negligible (when there is no room for its further decline). Another important recent development is the discovery of long-term 'memory' for early-life experiences in longevity determination. Siblings born to young mothers have significantly higher chances to live up to 100 years, and this new finding, confirmed by two independent research groups, calls for its explanation. As recent studies found, even the place and season of birth matter for human longevity. Beneficial longevity effects of young maternal age are observed only when children of the same parents are compared, while the maternal age effect often could not be detected in across-families studies, presumably being masked by between-family variation. It was also found that male gender of centenarian has a significant positive effect on the survival of adult male biological relatives (brothers and fathers) but not of female relatives. Finally, large gender differences are found in longevity determinants for males and females, suggesting a higher importance of occupation history for male centenarians as well as a higher importance of home environment history for female centenarians.

Early origins of longevity: prenatal exposures to food shortage among early Utah pioneers

Undernutrition during critical or sensitive prenatal periods may 'program' the fetus for increased chronic disease and mortality in later life. Using birth cohorts that were or were not exposed to severe food shortage in Utah in the mid-19th century, this study examines how in utero exposure to undernutrition is associated with mortality after age 50. The Utah Population Database is used to identify 1392 prenatally exposed individuals and 29,022 individuals from subsequent, unexposed birth cohorts. Gompertz hazards with parametric frailty show that males born between April and June of the famine period (and hence exposed during critical periods in utero during the winter months) have higher mortality risks compared with post-famine cohorts. Alternative Cox non-proportional hazard models suggest that females born during the same period have higher initial mortality risks (starting at age 50) that decline over time creating a mortality crossover with unexposed women at approximately age 70, a result not found for men. An ancillary sibling analysis that uses shared frailty survival models to compare individuals with prenatal exposure to undernutrition to their younger (post-famine) same-sex siblings finds no significant differences in adult mortality for males but the pattern for females support the findings from the previous analysis. Although findings are sensitive to model choice, this study presents evidence that is consistent with an association between undernutrition in utero and adult mortality, shows that effects may be sensitive to the duration and gestational period of exposure, and illustrates the differential exposure effects between genders.

Month of birth and cause-specific mortality between 50 and 80 years: a population-based longitudinal cohort study in Sweden

Month of birth-a proxy for a variety of prenatal and early postnatal exposures including nutritional status, ambient temperature and infections-has been linked to mortality risk in adult life. We assessed the relation between month of birth and cause-specific mortality risk from cardiovascular diseases, infections, tumors and external causes-in ages of more than 50-80 years. In this nation-wide Swedish study, 4,240,338 subjects were followed from 1991 to 2010, using data from population-based health and administrative registries. The relation between month of birth and cause-specific mortality risk was assessed by fitting Cox proportional hazard regression models with attained age as the underlying time scale. In models adjusted for sex and education, month of birth was associated with cardiovascular and infectious mortality, but not with deaths from tumors or external causes. Compared with subjects born in November, a higher cardiovascular mortality was seen in subjects born from January through August, peaking in March/April [hazard ratio (HR) 1.066 compared to November, 95 % CI 1.045-1.086]. The mortality from infections was lowest for the birth months November and December and a distinct peak was observed for September-born (HR 1.108 compared to November, 95 % CI 1.046-1.175). Month of birth is associated with mortality from cardiovascular diseases and infections in ages of more than 50-80 years in Sweden. The mechanisms behind these associations remain to be elucidated.

Predictors of Exceptional Longevity: Effects of Early-Life Childhood Conditions, Midlife Environment and Parental Characteristics

Knowledge of strong predictors of mortality and longevity is very important for actuarial science and practice. Earlier studies found that parental characteristics as well as early-life conditions and midlife environment play a significant role in survival to advanced ages. However, little is known about the simultaneous effects of these three factors on longevity. This ongoing study attempts to fill this gap by comparing centenarians born in the United States in 1890-91 with peers born in the same years who died at age 65. The records for centenarians and controls were taken from computerized family histories, which were then linked to 1900 and 1930 U.S. censuses. As a result of this linkage procedure, 765 records of confirmed centenarians and 783 records of controls were obtained. Analysis with multivariate logistic regression found that parental longevity and some midlife characteristics proved to be significant predictors of longevity while the role of childhood conditions was less important. More centenarians were born in the second half of the year compared to controls, suggesting early origins of longevity. We found the existence of both general and gender-specific predictors of human longevity. General predictors common for men and women are paternal and maternal longevity. Gender-specific predictors of male longevity are the farmer occupation at age 40, Northeastern region of birth in the United States and birth in the second half of year. A gender-specific predictor of female longevity is surprisingly the availability of radio in the household according to the 1930 U.S. census. Given the importance of familial longevity as an independent predictor of survival to advanced ages, we conducted a comparative study of biological and nonbiological relatives of centenarians using a larger sample of 1,945 validated U.S. centenarians born in 1880-95. We found that male gender of centenarian has significant positive effect on survival of adult male relatives (brothers and fathers) but not female blood relatives. Life span of centenarian siblings-in-law is lower compared to life span of centenarian siblings and does not depend on centenarian gender. Wives of male centenarians (who share lifestyle and living conditions) have a significantly better survival compared to wives of centenarians' brothers. This finding demonstrates an important role of shared familial environment and lifestyle in human longevity. The results of this study suggest that familial background, early-life conditions and midlife characteristics play an important role in longevity.

Within-mother analysis of seasonal patterns in health at birth

A large literature describes relationships between month of birth, birth weight, and gestation. These relationships are hypothesized to reflect the causal impact of seasonal environmental factors. However, recent work casts doubt on this interpretation by showing that mothers with lower socioeconomic status are more likely to give birth in months that are associated with poorer birth outcomes. Seasonality in the numbers of conceptions in different months can also induce a mechanical correlation between preterm birth and month of birth. This paper analyzes the seasonality of health at birth using a large sample of 647,050 groups of US siblings representing 1,435,213 children. By following the same mother over time, we eliminate differences in fixed maternal characteristics as an explanation for seasonal differences in health at birth. We find a sharp trough in gestation length among babies conceived in May, which corresponds to an increase in prematurity of more than 10%. Birth weight conditional on gestation length, however, is found to be strongly hump-shaped over the year, with 8-9 additional g for summer conceptions. We examine several potential mechanisms for explaining seasonality in birth outcomes that have generally been dismissed in the literature on seasonality in rich countries, notably disease prevalence and nutrition. The May trough in gestation length coincides with a higher influenza prevalence in January and February, when these babies are nearing full term, whereas the hump shape in birth weight is associated with a similar pattern in pregnancy weight gain.

Neuronal inputs and outputs of aging and longevity

An animal’s survival strongly depends on its ability to maintain homeostasis in response to the changing quality of its external and internal environment. This is achieved through intracellular and intercellular communication within and among different tissues. One of the organ systems that plays a major role in this communication and the maintenance of homeostasis is the nervous system. Here we highlight different aspects of the neuronal inputs and outputs of pathways that affect aging and longevity. Accordingly, we discuss how sensory inputs influence homeostasis and lifespan through the modulation of different types of neuronal signals, which reflects the complexity of the environmental cues that affect physiology. We also describe feedback, compensatory, and feed-forward mechanisms in these longevity-modulating pathways that are necessary for homeostasis. Finally, we consider the temporal requirements for these neuronal processes and the potential role of natural genetic variation in shaping the neurobiology of aging.

Determinants of exceptional human longevity: new ideas and findings

Studies of centenarians are useful in identifying factors leading to long life and avoidance of fatal diseases. In this article we consider several approaches to study effects of early-life and midlife conditions on survival to advanced ages: use of non-biological relatives as controls, the within-family analysis, as well as a sampling of controls from the same population universe as centenarians. These approaches are illustrated using data on American centenarians, their relatives and unrelated shorter-lived controls obtained from the online genealogies. The within-family analysis revealed that young maternal age at person's birth is associated with higher chances of exceptional longevity. Comparison of centenarians and their shorter-lived peers (died at age 65 and sampled from the same pool of online genealogies) confirmed that birth timing in the second half of the calendar year predicts survival to age 100. Parental longevity as well as some childhood and midlife characteristics also proved to be significant predictors of exceptional longevity.

Effect of birth season on longevity: thrifty and hopeful phenotypes in historical Quebec

OBJECTIVES

Individuals with fetal growth restrictions may become unhealthy as adult if they live in a nutritionally rich environment. Yet, there is little evidence for the counterpart that profuse resources during early development may prove detrimental in an impoverished adult environment. Using birth season as a proxy for nutrition in utero, this study tests whether early life effects on longevity are conditional on the environment in which people reside during adulthood.

METHODS

I used Cox proportional hazard models of mortality after the age of 60 years among historical cohorts of French Canadian women born before 1750. Models are stratified by siblings to adjust the results for unobserved factors shared by family members.

RESULTS

A birth during winter conferred the best-survival prospects in the south of the Saint-Lawrence River but the worse prospects in the north, where a birth during the fall was associated with the lowest mortality. Women who migrated to live on the other side of the river lost whatever advantage or disadvantage they had from their birth season and faced increases or decreases in risk that were specific to their new location.

CONCLUSIONS

Based on Hales and Barker's thrifty phenotype hypothesis, and adding the "hopeful phenotype" counterpart, this study suggests that cues from the external environment during development are highly specific to that environment and that the slightest change of location may affect the chances for survival into old age. I finally address the role of fertility as a possible mediator or modifier of the effect of birth season on longevity.