Early Life Conditions Research Articles

Morphological and physiological consequences of a dietary restriction during early life in bats

Abstract Early life adverse conditions can have major consequences on an individual’s life history traits. Oxidative stress has been hypothesized to be one main mechanism underlying the negative consequences of early life adverse conditions. To test this hypothesis, we restricted the food availability of Seba’s short-tailed bat (Carollia perspicillata) mothers of unweaned pups for 10 days, followed by ad libitum provisioning. We also had a control, unrestricted group. We explored the morphological consequences of dietary restriction during early life by measuring growth rate. We also measured four markers of blood oxidative balance during growth. We assessed the level of cortisol, and its inactive form cortisone, in the hair of the pups at the end of growth. Finally, we monitored survival during the first year. Food restriction triggered a slowdown in growth followed by catch-up growth when ad libitum feeding was restored which did not lead to full compensation in size or mass compared to control individuals. We found that higher growth rate was associated with elevated oxidative damage, suggesting an oxidative cost to growth. However, we found no clear evidence for physiological costs specific to the catch-up growth. Survival after a year was not impacted by the treatment, the oxidative balance or the level of glucocorticoids at the end of growth. In conclusion, our results show that individuals were able to efficiently mitigate the short-term consequences of adverse early life conditions. However, consequences might arise in the long-term, and could impact reproductive success or lifespan.

Neonatal Thyroid Stimulating Hormone and Subsequent Diagnosis of Autism Spectrum Disorders and Intellectual Disability.

Hypothyroid conditions in early life, if left untreated, are associated with adverse neurodevelopmental outcomes, including intellectual disability (ID). However, evidence addressing the role of neonatal thyroid hormone insufficiencies in the altered neurobiology underlying autism spectrum disorders (ASD), particularly among its subphenotypes, is limited. We conducted a population-based, case-control study among a sample of children born during 2000-2003 in Southern California. We examined neonatal thyroid-stimulating hormone (TSH) measured during routine newborn screening among children later diagnosed with ASD (n = 518) or ID (n = 145) and general population (GP) controls (n = 399). TSH was further analyzed in relation to ASD subgroups of intellectual ability and onset type (early-onset ASD vs. ASD with regression) ascertained by expert review of developmental services records. Odds ratios (ORs) of the differences in TSH between groups were obtained from multivariate logistic regression. We examined neonatal TSH as continuous (ln-transformed) and as quartiles. We found no association between continuous neonatal TSH levels and ASD (adj-OR: 1.00, 95% CI: 0.79-1.26) nor ID (adj-OR = 1.01, 95% CI: 0.73-1.40). Among ASD subphenotypes, we observed a suggestive inverse trend between ASD with regression and TSH, though the association only reached statistical significance in the highest TSH quartile (adj-OR: 0.50, 95% CI: 0.26-0.98). While there was little evidence that neonatal TSH is related to overall ASD risk, more work is needed to understand the influence of thyroid hormones on ASD subphenotypes. Autism Res 2020, 13: 444-455. © 2019 International Society for Autism Research,Wiley Periodicals, Inc. LAY SUMMARY: Low levels of thyroid hormone at birth can negatively impact brain development. We studied whether newborn levels of thyroid stimulating hormone (TSH) were associated with autism spectrum disorder (ASD) and its subtypes in a sample of children born in California. Newborn TSH was not related to the overall risk of ASD or intellectual disability. However, the relationships of thyroid hormone levels at birth and specific subtypes of ASD, particularly ASD with developmental regression, may need more research.

Developmental temperature predicts the adult response to stressors in a free-living passerine.

Early-life conditions can have substantial effects on the ways animals respond to stressors as adults. In particular, thermal conditions during development affect juveniles' responses to stressors, and there is evidence that these effects may extend into adulthood. However, these effects remain poorly understood, especially in free-living organisms. We test the prediction that ambient temperatures during laying, embryonic development and nestling development affect the hormonal mediators of the response to stressors in adults. To do so, we use a long-term dataset of tree swallows (Tachycineta bicolor) with records from both natal development and adult breeding. We found a strong, negative relationship between ambient temperature during early development (incubation) and an individual's corticosterone (CORT) response to stress later in life (while incubating her own young). Thermal conditions during other stages of natal development also showed a weak relationship with baseline CORT during provisioning. In a post hoc analysis, we found no evidence that ambient temperature during development differentially influenced the survival and recruitment of juveniles with different CORT phenotypes. Our results show that thermal conditions during development can have long-term effects on how individuals respond to stressors.

Prevalence and determinants of type 2 diabetes among lean African migrants and non-migrants: the RODAM study.

BackgroundExposure to adverse conditions earlier in life-course can predispose to type 2 diabetes in adulthood, irrespective of body mass index (BMI). However, the burden of type 2 diabetes in lean Africans is not well understood despite higher exposure to adverse early life conditions. Mirroring ongoing epidemiological transition, we assessed the burden and determinants of type 2 diabetes in a homogenous group of lean Ghanaians residing in rural and urban Ghana, and as migrants in Europe.MethodsBaseline data from 2179 RODAM study participants with BMI<25kg/m2 (25-70 years) were analyzed. Prevalence and determinants of type 2 diabetes were estimated using logistic regression analysis. Adjustments were made for socio-demographic and lifestyle factors, use of anti-diabetic medication and optimal blood glucose control.ResultsPrevalence of type 2 diabetes in rural, urban and migrant lean participants were 3.5%, 8.9% and 7.5% respectively, representing 55.4%, 35.6%, 13.2% of all participants with type 2 diabetes. Compared with lean rural participants, the odds of type 2 diabetes were higher in lean urban participants (adjusted OR = 8.81, 95% CI = 6.56-11.06), followed by migrants (5.27, 95% CI = 3.51-6.91). Irrespective of site, determinants of type 2 diabetes in lean participants include; presence of hypertension, physical inactivity, hypercholesterolemia and age (>45 years).ConclusionsOur study shows a high prevalence of type 2 diabetes among lean African populations in different geographical settings. Future studies are needed in-order to examine how contextual differences are related to the pathophysiology of type 2 diabetes in lean individuals.

Molar-incisor malformation: Eight new cases and a review of the literature.

Molar-incisor malformation (MIM) is a recently described dental abnormality. While MIM mimics dentin dysplasia, it presents in a localized pattern. Furthermore, it is speculated that MIM is caused by significant early-life medical history. The purpose of this study is to present a series of MIM cases and compare the findings with the literature. An extensive search of all published cases of MIM in the English-language literature was conducted. Additionally, an institutional review board-approved retrospective search was performed within the University of Florida oral pathology biopsy service archives. Radiographic consultation cases were also included. Cases lacking radiographs were excluded. Seventy-nine cases were identified in the literature, and eight cases were identified in our retrospective search. All but one case involved the permanent first molars. The average age at diagnosis was 9years. Many patients reported significant early-life medical histories. MIM usually affects the permanent first molars and may be linked to early-life medical conditions or interventions. Oral healthcare providers, especially paediatric dentists, should be aware of MIM to avoid misdiagnosing it as dentin dysplasia. Long-term follow-up studies with thorough medical history documentation are essential to understand the pathogenesis and aetiology and to create treatment guidelines.

Effects of early life and current housing on sensitivity to reward loss in a successive negative contrast test in pigs

Animals in a negative affective state seem to be more sensitive to reward loss, i.e. an unexpected decrease in reward size. The aim of this study was to investigate whether early-life and current enriched vs. barren housing conditions affect the sensitivity to reward loss in pigs using a successive negative contrast test. Pigs (n = 64 from 32 pens) were housed in barren or enriched conditions from birth onwards, and at 7 weeks of age experienced either a switch in housing conditions (from barren to enriched or vice versa) or not. Allotting pigs to the different treatments was balanced for coping style (proactive vs. reactive). One pig per pen was trained to run for a large reward and one for a small reward. Reward loss was introduced for pigs receiving the large reward after 11 days (reward downshift), i.e. from then onwards, they received the small reward. Pigs housed in barren conditions throughout life generally had a lower probability and higher latency to get the reward than other pigs. Proactive pigs ran overall slower than reactive pigs. After the reward downshift, all pigs ran slower. Nevertheless, reward downshift increased the latency and reduced the probability to get to the reward, but only in pigs exposed to barren conditions in early life, which thus were more sensitive to reward loss than pigs from enriched early life housing. In conclusion, barren housed pigs seemed overall less motivated for the reward, and early life housing conditions had long-term effects on the sensitivity to reward loss.

SOCIOECONOMIC, BIOLOGICAL, AND COMMUNITY ASSOCIATIONS WITH OLD-AGE MORTALITY IN CHINA

Determinants of mortality may differ depending on context. This study uses a nationally representative sample of persons aged 60 and over in China to determine if socioeconomic factors, early life conditions, community characteristics, biological and physical functioning, and disease burden predict four-year all-cause mortality. We employed a series of Weibull hazard models based on exact survival time to predict mortality. We find that current education and place of residence, physical functioning, uncontrolled hypertension, diabetes, cancer, a high level of systemic inflammation, and poor kidney functioning are strong predictors of mortality among older Chinese. We did not find linkages between early-life experiences or community infrastructure to mortality at older ages. Results from this study highlight the value of incorporating biological and performance measurements and the importance of social and historical context in studying old-age mortality.

THE INTERGENERATIONAL EFFECTS OF THE NEW DEAL WORK RELIEF PROGRAMS ON LATE-LIFE OUTCOMES: AN 80-PLUS-YEAR FOLLOW-UP STUDY

Evidence from multiple disciplines suggests that early‐life conditions and environments affect outcomes across the life course. However, less is known about the effects of policy interventions targeted to adults and communities that may have intergenerational consequences on exposed children. In this study, we undertake novel data linkages to examine the effects of the New Deal work–relief programs on long-term health, disability and mortality outcomes of children born between 1920-1940. We first link the American Manufacturing Cohort (AMC) workforce backward to their childhood census records to capture parental and community exposure to New Deal work-relief programs. We then test the hypothesis that employment in New Deal work-relief programs is associated with lower levels of chronic disease, lower rates of disability and delayed mortality for both the children in benefitting households and children in non-benefit households living in areas that received greater amounts of New Deal funding.

Colonisation of the proximal intestinal remnant in newborn infants with enterostomy: a longitudinal study protocol

IntroductionThe gut microbiota plays a main role in the maintenance of host’s health. Exposure to different conditions in early life contributes to distinct ‘pioneer’ bacterial communities in the intestine, which...

Early Life Respiratory Status and Adult Occupational Exposures

TPS 792: Occupational health 2, Exhibition Hall, Ground floor, August 27, 2019, 3:00 PM - 4:30 PM Background/Aims Respiratory status in early life may be associated with adult occupational exposures. This has been hypothesized to create a “healthy worker” bias, where persons with better respiratory status may be more likely to self-select into and remain in jobs with more adverse occupational exposures. We evaluated associations between childhood respiratory function and occupational exposures in early adulthood in a longitudinal respiratory birth cohort. Methods: The Tucson Children’s Respiratory Study (CRS) enrolled participants at birth in the 1980s. At age 11, pre- and post-bronchodilator measures of FEV1, FVC, FEV1/FVC Ratio, & FEF25-75% were assessed. We used the Global Lung Function Index to calculate percent predicted values, which account for race, sex, height, and age. At age 26, participants self-reported dust, smoke, and/or fume/gas exposures (binary) at current and prior jobs. We used logistic regression to evaluate whether percent predicted pre- and post-bronchodilator lung function at age 11 was associated with self-reported occupational exposures at first job (N=384). We also examined modification by length of time at job (binary, >= 12 months, alpha=0.15). We controlled for maternal education, smoking during pregnancy, participant smoking at age 22, and Hispanic ethnicity. Results: Post-bronchodilator measures of percent-predicted FEV1/FVC Ratio and FEF were associated with occupational dust (OR-FEV1/FVCratio for 1% increase=1.03, 95%CI=1.00-1.07; OR-FEF=1.01, 95%CI=1.00-1.02), while FEV1 and FVC were associated with occupational smoke (OR-FEV1=1.03, 95%CI=1.01-1.06; OR-FVC=1.03, 95%CI=1.01-1.06). In interaction models, among participants employed in first job >=12 months (N=314), post-bronchodilator FEV1, FEV1/FVC ratio, and FEF, were associated with dust (OR-FEV1=1.03, 95%CI=1.01-1.06; OR-Ratio=1.05, 95%CI=1.01-1.09; OR-FEF=1.02, 95%CI=1.00-1.03; p-interactions all<0.10), and FVC was associated with smoke (OR-FVC=1.05, 95%CI=1.02-1.07, p-interaction=0.12). Estimates were similar for pre-bronchodilator values. Conclusions: These results support the premise of the healthy worker effect hypothesis. Better lung function, as early as age 11, is associated with greater adverse occupational exposures in this general population cohort.

Silver spoon effects are constrained under extreme adult environmental conditions.

Early-life environmental conditions may generate cohort differences in individual fitness, subsequently affecting population growth rates. Three, nonmutually exclusive hypotheses predict the nature of these fitness differences: (1) silver spoon effects, where individuals born in good conditions perform better across the range of adult environments; (2) the "environmental saturation" hypothesis, where fitness differences only occur in intermediate adult environmental conditions; and (3) the "environmental matching" or "predictive adaptive response" (PAR) hypothesis, where fitness is highest when adult environmental conditions match those experienced in early life. We quantified the context-dependent effect of early-life environment on subsequent reproductive success, survival, and population growth rate (λ) of Svalbard reindeer, and explored how well it was explained by the three hypotheses. We found that good early-life conditions increased reproductive success compared to poor early-life conditions, but only when experiencing intermediate adult environmental conditions. This is the first example of what appears to be both "beneficial" and "detrimental environmental saturation" in a natural system. Despite weak early-life effects on survival, cohorts experiencing good early-life conditions contributed to higher population growth rates, when simulating realistic variation in adult environmental conditions. Our results show how the combination of a highly variable environment and biological constraints on fitness components can suppress silver spoon effects at both extremes of the adult environmental gradient.

Early-life conditions determine the between-individual heterogeneity in plasticity of calving date in reindeer.

Phenotypic plasticity has become a key concept to enhance our ability to understand the adaptive potential of species to track the pace of climate change by allowing a relatively rapid adjustment of life-history traits. Recently, population-level trends of an earlier timing of reproduction to climate change have been highlighted in many taxa, but only few studies have explicitly taken into consideration between-individual heterogeneity in phenotypic plasticity. Using a long-term data of a semi-domesticated reindeer (Rangifer tarandus) population, we demonstrated that females differed greatly in their mean calving date but only slightly in the magnitude of their plastic response to the amount of precipitation in April. We also showed that despite the absence of a population trend, females individually responded to the amount of precipitation in April by delaying their calving dates. Females' calving date under average climatic conditions was best predicted by their birthdate, by their physical condition in March-April-May before their first calving season and by their first calving date. The degree of their phenotypic plasticity was not dependent on any of the females' attributes early in life tested in this study. However, females who delayed their calving dates in response to a higher amount of precipitation in April slightly produced less calves over their reproductive life. These findings confirmed that early-life conditions of female reindeer can shape their phenotypic value during reproductive life, supporting the importance of maternal effects in shaping individuals' lifetime reproductive success. Whether females differed in the magnitude of their plastic response to climatic changes has received contrasted responses for various ungulate species. This calls for more research to enhance our understanding of the underlying mechanisms, leading to the complexity of plastic responses among populations to cope with current climate change.

Determinants of Influenza Mortality Trends: Age-Period-Cohort Analysis of Influenza Mortality in the United States, 1959\u20132016

This study examines the roles of age, period, and cohort in influenza mortality trends over the years 1959–2016 in the United States. First, we use Lexis surfaces based on Serfling models to highlight influenza mortality patterns as well as to identify lingering effects of early-life exposure to specific influenza virus subtypes (e.g., H1N1, H3N2). Second, we use age-period-cohort (APC) methods to explore APC linear trends and identify changes in the slope of these trends (contrasts). Our analyses reveal a series of breakpoints where the magnitude and direction of birth cohort trends significantly change, mostly corresponding to years in which important antigenic drifts or shifts took place (i.e., 1947, 1957, 1968, and 1978). Whereas child, youth, and adult influenza mortality appear to be influenced by a combination of cohort- and period-specific factors, reflecting the interaction between the antigenic experience of the population and the evolution of the influenza virus itself, mortality patterns of the elderly appear to be molded by broader cohort factors. The latter would reflect the processes of physiological capital improvement in successive birth cohorts through secular changes in early-life conditions. Antigenic imprinting, cohort morbidity phenotype, and other mechanisms that can generate the observed cohort effects, including the baby boom, are discussed.

Do Cesarean Delivery rates rise when the economy declines? A test of the economic stress hypothesis

A growing body of research supports the Barker hypothesis that adverse conditions around the time of birth have a negative effect on health. Nevertheless, the mechanisms linking early life conditions with health are still unclear. This paper investigates one of such potential mechanisms, specifically, ambient stress, by analyzing the effect of economic downturns as a stressor on the probability of Cesarean Delivery (CD). I focus particularly on male CD since the literature reports that male fetuses are more sensitive to stressors in utero than female fetuses. Using data from Lifelines, a large cohort study from the northern Netherlands, I show that the probability of CD for male babies increases when unemployment levels rise. This result suggests that maternal stress might be one of the mechanisms how early life economic conditions affect health.

Individual variation in early-life telomere length and survival in a wild mammal.

Individual variation in survival probability due to differential responses to early-life environmental conditions is important in the evolution of life histories and senescence. A biomarker allowing quantification of such individual variation, and which links early-life environmental conditions with survival by providing a measure of conditions experienced, is telomere length. Here, we examined telomere dynamics among 24 cohorts of European badgers (Meles meles). We found a complex cross-sectional relationship between telomere length and age, with no apparent loss over the first 29months, but with both decreases and increases in telomere length at older ages. Overall, we found low within-individual consistency in telomere length across individual lifetimes. Importantly, we also observed increases in telomere length within individuals, which could not be explained by measurement error alone. We found no significant sex differences in telomere length, and provide evidence that early-life telomere length predicts lifespan. However, while early-life telomere length predicted survival to adulthood (≥1 year old), early-life telomere length did not predict adult survival probability. Furthermore, adult telomere length did not predict survival to the subsequent year. These results show that the relationship between early-life telomere length and lifespan was driven by conditions in early-life, where early-life telomere length varied strongly among cohorts. Our data provide evidence for associations between early-life telomere length and individual life history, and highlight the dynamics of telomere length across individual lifetimes due to individuals experiencing different early-life environments.

Time Spent With Parents Varies With Early-Life Condition, but Does Not Predict Survival or Sociality of Juvenile Hihi

Many young birds die soon after fledging, as they lack the skills to find food and avoid predation. Post-fledging parental care is assumed to assist acquisition of these vital skills. However, we still lack empirical examples examining the length of time fledglings spend with parents, how they associate during this critical time, or whether such variation in the fledgling dependency period has consequences for the survival and behaviour of young as they navigate their first year of independent life. Here, we make use of observations and radio frequency identity (RFID) logs of visits to supplementary feeding stations to investigate how condition of fledgling hihi (stitchbird, Notiomystis cincta), a New Zealand passerine, predicts dispersal behaviour and tendency to follow parents during their two week post-fledging dependence period. We find that thinner fledglings followed their parents more closely in time when visiting feeding stations, compared to fatter siblings (all following ranged from 3 sec to 10 min). However, broods in poorer condition tended to disperse from the natal territory up to 6.5 days earlier than broods of fatter fledglings (all dispersed within 14 days). Our results did not find that sociality or survival during the first year of life differed depending on variation in fledgling behaviour; neither following parents closely nor dispersing later predicted each bird’s number of associates (degree), or survival over winter. These results suggest that fledglings may be able to compensate for early differences in condition with behaviour, either during the post-fledging dependence period or when independent.

In the Long Run: Physical Activity in Early Life and Cognitive Aging.

A certain degree of age-related cognitive decline is normal; however, some people retain more cognitive function than others. Cognitive impairment is associated with an increased risk of dementia. Thus, understanding the factors that contribute to cognitive reserve is crucial, so effective strategies for the prevention of dementia can be developed. Engaging in physical activity can delay cognitive decline and reduce the risk of dementia and a number of early life conditions have been shown to have long-lasting effects on cognition. This mini-review combines these two observations to evaluate the evidence from both animal models and epidemiological studies for physical activity in early life (≤30 years) delaying cognitive decline in later life (cognition tested ≥60 years). Three epidemiological studies were found; two showed a positive association and one found none. The latter was deemed to have an unreliable method. A review of animal studies found none that analyzed the effect of physical activity in early life on cognition in later life. However, in rodent models that analyzed mid-life cognition, runners showed improved cognition and enhanced adult hippocampal neurogenesis, changes which were preserved across the life span. Currently, there is insufficient evidence to conclude whether physical activity in early life may delay cognitive decline in later life, but these results indicate that further studies are warranted. Future human research should be in the form of longitudinal studies that begin below ≤15 years and assess sex differences. Crucially, the physical activity data must define type, quantity and intensity of exercise.

A longitudinal birth cohort study of early life conditions, psychosocial factors, and emerging adolescent sexual orientation

This study tested whether previously reported associations between early life factors and later adolescent sexual orientation could be replicated in another prospective birth cohort, the UK Millennium Cohort Study (MCS). We used data on 9,795 youth from the MCS. Emerging sexual orientation was assessed using measures of sexual attraction to males and females in separate items at 14years. Factors including birthweight, breastfeeding, sibling composition, parental ages, maternal psychopathology, parent-child relationship, and contextual risks were separated into three developmental periods: prenatal (n=5 factors), before 7years (n=6 factors), and after 7years (n=5 factors). We controlled for handedness as a putative marker of prenatal androgen exposure and the possibility of mischievous responding statistically. Girls with greater maternal psychological distress since age 7 and greater pubertal body mass index were more likely to be nonheterosexual but the effect sizes were very small. Among boys there were no significant associations between any early life conditions and later sexual orientation. However, focusing on effect sizes rather than significance levels, there were small associations between preterm birth and nonheterosexuality. The results offer further evidence that psychosocial influences in the development of adolescent sexual orientation are weak or non-existent.

Genome-wide variation in DNA methylation is associated with stress resilience and plumage brightness in a wild bird.

Individuals often differ in their ability to cope with challenging environmental and social conditions. Evidence from model systems suggests that patterns of DNA methylation are associated with variation in coping ability. These associations could arise directly if methylation plays a role in controlling the physiological response to stressors by, among other things, regulating the release of glucocorticoids in response to challenges. Alternatively, the association could arise indirectly if methylation and resilience have a common cause, such as early-life conditions. In either case, methylation might act as a biomarker for coping ability. At present, however, relatively little is known about whether variation in methylation is associated with organismal performance and resilience under natural conditions. We studied genome-wide patterns of DNA methylation in free-living female tree swallows (Tachycineta bicolor) using methylated DNA immunoprecipitation (MeDIP) and a tree swallow genome that was assembled for this study. We identified areas of the genome that were differentially methylated with respect to social signal expression (breast brightness) and physiological traits (ability to terminate the glucocorticoid stress response through negative feedback). We also asked whether methylation predicted resilience to a subsequent experimentally imposed challenge. Individuals with brighter breast plumage and higher stress resilience had lower methylation at differentially methylated regions across the genome. Thus, widespread differences in methylation predicted both social signal expression and the response to future challenges under natural conditions. These results have implications for predicting individual differences in resilience, and for understanding the mechanistic basis of resilience and its environmental and social mediators.

"Closer-to-home" strategy benefits juvenile survival in a long-distance migratory bird.

Human‐induced changes in the climate and environment that occur at an unprecedented speed are challenging the existence of migratory species. Faced with these new challenges, species with diverse and flexible migratory behaviors may suffer less from population decline, as they may be better at responding to these changes by altering their migratory behavior. At the individual level, variations in migratory behavior may lead to differences in fitness and subsequently influence the population's demographic dynamics. Using lifetime GPS bio‐logging data from 169 white storks (Ciconia ciconia), we explore whether the recently shortened migration distance of storks affects their survival during different stages of their juvenile life. We also explore how other variations in migratory decisions (i.e., time, destination), movement activity (measured using overall body dynamic acceleration), and early life conditions influence juvenile survival. We observed that their first autumn migration was the riskiest period for juvenile white storks. Individuals that migrated shorter distances and fledged earlier experienced lower mortality risks. In addition, higher movement activity and overwintering “closer‐to‐home” (with 84.21% of the tracked individuals stayed Europe or North Africa) were associated with higher survival. Our study shows how avian migrants can change life history decisions over only a few decades, and thus it helps us to understand and predict how migrants respond to the rapidly changing world.