Early life effects across the life course: the impact of individually defined exogenous measures of disease exposure on mortality by sex in 19th- and 20th-century Southern Sweden

Social inequalities in adult mortality across Europe (18th-21st centuries): A critical analysis of theories and evidence

This study examines the historical evolution of socioeconomic disparities in adult mortality, with a focus on European societies. Despite the widespread improvements in population health, social inequalities in mortality are a pervasive phenomenon nowadays. This paper employs a critical analysis of both theoretical and empirical literature to investigate major international studies and their findings on longevity differences associated with socioeconomic status from the nineteenth century to the early twenty-first century. Findings reveal that adult mortality trajectories have differed notably across social classes and regions, with some areas exhibiting disparities before the demographic transition and others showing inequalities emerging later. Understanding these long-term health inequality trends sheds light on the changing influence of medical advances and their interplay with economic growth, educational disparities, environmental factors, state roles, and production distribution, which have shaped mortality disparities through different development stages. These factors elucidate the international heterogeneity of results until the mid-twentieth century and offer explanatory insights into observed north-south patterns in Europe. Our findings contribute to a deeper understanding of how advancements in public health, economic development, and social policies have shaped health outcomes over centuries. The implications of this research inform ongoing debates and health policy, emphasizing a nuanced interpretation of historical data to craft effective strategies that address health inequalities today.

Early-Life Disease Exposure and Its Heterogeneous Effects on Mortality Throughout Life: Sweden, 1905-2016

Exposure to infectious diseases in early life has been linked to increased mortality risk in later life in high-disease settings, such as eighteenth- and nineteenth-century Europe. Less is known about the long-term effects of early-life disease exposure in milder disease environments. This study estimates heterogeneous effects from disease exposure in infancy on later-life mortality in twentieth-century Sweden, by socioeconomic status at birth and sex. Using historical population data for southern Sweden, we study 11,515 individuals who were born in 1905-1929 from age 1 until age 85. We measure exposure to disease using the local post-early neonatal mortality rate in the first 12 months after birth and apply flexible parametric survival models. For females, we find a negative effect on life expectancy (scarring) at ages 1-85 following high disease exposure in infancy, particularly for those born to unskilled workers. For males, we find no negative effect on later-life survival, likely because stronger mortality selection in infancy outweighs scarring. Thus, even as the incidence of infectious diseases declined at the start of the twentieth century, early-life disease exposure generated long-lasting negative but heterogeneous population health effects.

Vestiges of famine: Long-term mortality impacts of early-life exposure to the 1840s famine in Estonia

The paper investigates whether exposure to a famine in the Russian Tsarist Province of Livland in 1844-1846 in early life negatively affected survival at later ages, using individual data from two rural parishes. We follow 18 birth cohorts born between 1834-1852 until age 75 and differentiate between timing and length of exposures. We find that relative to individuals born in pre- or post- crisis years, there were no significant differences in survival from age 21-75. Cohorts with longer exposure to famine conditions had increased mortality only in short term, up to age 20. Males were more vulnerable in younger ages than females. The negative effect of adverse early life exposure on survival in later life was constrained to lower social group - the landless, but for the better-off groups the effect was constrained to younger ages. The paper highlights the importance of accounting for sex and socio-economic differences in studies exploring the effects of early life conditions on later-life survival.

Has it always paid to be rich? Income and cause-specific mortality in southern Sweden 1905-2014

Socio-economic differences in mortality are among the most pervasive characteristics of Western societies. While the mortality gradient by income is well established for the period after 1970, knowledge about the origins of this gradient is still rudimentary. We analyse the association between income and cause-specific adult mortality during the period 1905-2014 in an area of southern Sweden, using competing-risk hazard models with individual-level longitudinal data for over 2.2 million person-years and over 35,000 deaths. We find that the present-day income gradient in adult mortality emerged only in the period after the Second World War and did so for the leading causes of death and for men and women largely simultaneously.

Separating Scarring Effect and Selection of Early-Life Exposures With Genetic Data

Causal life course research examining consequences of early-life exposures has largely relied on associations between early-life environments and later-life outcomes using exogenous environmental shocks. Nonetheless, even with (quasi-)randomized early-life exposures, these associations may reflect not only causation ("scarring") but also selection (i.e., which members are included in data assessing later life). Investigating this selection and its impacts on estimated effects of early-life conditions has, however, often been ignored because of a lack of pre-exposure data. This study proposes an approach for assessing and correcting selection, separately from scarring, using genetic measurements. Because genetic measurements are determined at the time of conception, any associations with early-life exposures should be interpreted as selection. Using data from the UK Biobank, we find that in utero exposure to a higher area-level infant mortality rate is associated with genetic predispositions correlated with better educational attainment and health. These findings point to the direction and magnitude of selection from this exposure. Corrections for this selection in examinations of effects of exposure on later educational attainment suggest underestimates of 26-74%; effects on other life course outcomes also vary across selection correction methods.

Disease exposure in infancy affects women's reproductive outcomes and offspring health in southern Sweden 1905-2000

Ample evidence demonstrates that early-life adversity negatively affects morbidity and survival in late life. We show that disease exposure in infancy also has a continuous impact on reproduction and health across the female life course and even affects early-life health of the next generation. Using Swedish administrative data, obstetric records, and local infant mortality rates as a measure of disease exposure, we follow women's reproductive careers and offspring health 1905-2000, examining a comprehensive set of outcomes. Women exposed to disease in infancy give birth to a lower proportion of boys, consistent with notions that male fetuses are more vulnerable to adverse conditions and are more often miscarried. Sons of exposed mothers are also more likely to be born preterm and have higher birthweight suggesting in utero out-selection. Exposed women have a greater risk of miscarriage and of male stillbirth, but their overall likelihood of giving birth is not affected.

Area-Level Infant Mortality Exposure in Early Life and Alzheimer's Disease Mortality: Examining Variation Based on Age, Sex, and Place of Birth

BACKGROUND

Growing evidence suggests that critical periods in early life may contribute to one's risk of Alzheimer's disease and related dementias (ADRD) in later life. In this paper we explore the role that exposure to infant mortality plays in later life ADRD.

OBJECTIVE

To determine if exposure to early life infant mortality is associated with later mortality from ADRD. Also, we explore how these associations differ by sex and age group, along with the role of state of birth and competing risks of death.

METHODS

We use a sample of over 400,000 individuals aged 50 and above with the NIH-AARP Diet and Health Study with mortality follow-up, allowing us to examine how early life infant mortality rates along with other risk factors play in one's individual mortality risk.

RESULTS

We show that infant mortality rates are associated with death from ADRD among those under 65 years of age, but not those over 65 at baseline interview. Moreover, when factoring in competing risks of death, the associations are relatively unchanged.

CONCLUSION

These results suggest that those exposed to worse adverse conditions during critical periods increase their likelihood of death from ADRD earlier than average, due to that exposure increasing their susceptibility to develop illness later on in life.

Early life environments and cognition in adulthood: New evidence using a semiparametric approach and quantile regression

Theories and empirical evidence document the importance of early life environmental factors on later life cognition. A next question is how and in what dimension associations between early life environments and later life cognition vary. Using data from the UK Biobank in conjunction with time-place-specific infant mortality rates, we assessed heterogeneous and non-linear associations between early life conditions and later life cognition. We found that the association between the infant mortality rate and later life cognition increased once the UK achieved very low infant mortality rates, suggesting that additional decreases in infant mortality rates in an industrialized society continue to improve later life cognition. We also found that infant mortality rates have stronger effects at upper quantiles of the cognition distribution. This implies that adverse early life environments may have an important role for an early manifestation of cognitive aging.

Were there long-term economic effects of exposure to polio vaccination? An analysis of migrants to Sweden 1946-2003

Recent research showed that exposure to the vaccine against polio in early life had no long-term economic benefits among native Swedes. However, whether this result holds for individuals from other countries remains unexplored. This study explores the relationship between exposure to the vaccine and later-life outcomes, but focuses on individuals who migrated to Sweden (birth cohorts 1946-1971), and constitute a diverse sample in terms of national origin. Using a differences-in-differences approach and register data from the Swedish Longitudinal Immigrant Database, this study explores if being exposed to the vaccine against polio in the year of birth in the country of origin has any impact on adult income, educational achievement, or days or number of hospitalizations. The results are in line with the previous research in showing that there are no statistically significant effects on adult income, education, or health from exposure to the vaccine against polio, regardless of national origin. Furthermore, no scarring effects of exposure to polio epidemics were found on any of the outcomes, reinforcing the hypothesis that polio did not scar individuals in the same way as other contemporary epidemic diseases did, and that the lack of scarring could explain the absence of long-term impact from vaccine exposure.

The Long Harm of Childhood: Childhood Exposure to Mortality and Subsequent Risk of Adult Mortality in Utah and The Netherlands

How do early-life conditions affect adult mortality? Research has yielded mixed evidence about the influence of infant and child mortality in birth cohorts on adult health and mortality. Studies rarely consider the specific role of mortality within the family. We estimated how individuals' exposure to mortality as a child is related to their adult mortality risk between ages 18 and 85 in two historical populations, Utah (USA) 1874-2015 and Zeeland (The Netherlands) 1812-1957. We examined these associations for early community-level exposure to infant and early (before sixth birthday) and late (before eighteenth birthday) childhood mortality as well as exposure during these ages to sibling deaths. We find that that exposure in childhood to community mortality and sibling deaths increases adult mortality rates. Effects of sibling mortality on adult all-cause mortality risk were stronger in Utah, where sibling deaths were less common in relation to Zeeland. Exposure to sibling death due to infection was related to the surviving siblings' risk of adult mortality due to cardiovascular disease (relative risk: 1.06) and metabolic disease (relative risk: 1.42), primarily diabetes mellitus, a result consistent with an inflammatory immune response mechanism. We conclude that early-life conditions and exposure to mortality in early life, especially within families of origin, contribute to adult mortality.

Inequality and demographic response to short-term economic stress in North Orkney, Scotland, 1855-1910: Sector differences

We examine economic inequality and social differences in infant and child mortality, and fertility responses to food price changes in North Orkney, 1855-1910, using linked vital records. This small population featured a diverse occupational structure, limited land resources, and geographic isolation from mainland Scotland. Segments of Orkney's non-agricultural working population were living so close to the margin of subsistence in normal years that an increase in food prices in bad years cost the lives of their children. Delayed childbearing, in addition to increased labour intensity, occupational diversification, and poor relief, failed to mitigate the negative effects of unfavourable prices in this group. While previous studies for Western Europe show a strong social gradient in mortality responses to food prices, and for Eastern Asia a strong household gradient, this study shows a strong sectoral gradient, indicating low standards of living for the non-agricultural working population well into the twentieth century.

Spatiotemporal historical datasets at micro-level for geocoded individuals in five Swedish parishes, 1813-1914

This paper presents datasets that enable historical longitudinal studies of micro-level geographic factors in a rural setting. These types of datasets are new, as historical demography studies have generally failed to properly include the micro-level geographic factors. Our datasets describe the geography over five Swedish rural parishes, and by linking them to a longitudinal demographic database, we obtain a geocoded population (at the property unit level) for this area for the period 1813-1914. The population is a subset of the Scanian Economic Demographic Database (SEDD). The geographic information includes the following feature types: property units, wetlands, buildings, roads and railroads. The property units and wetlands are stored in object-lifeline time representations (information about creation, changes and ends of objects are recorded in time), whereas the other feature types are stored as snapshots in time. Thus, the datasets present one of the first opportunities to study historical spatio-temporal patterns at the micro-level.

Early-life disease exposure and associations with adult survival, cause of death, and reproductive success in preindustrial humans

A leading hypothesis proposes that increased human life span since 1850 has resulted from decreased exposure to childhood infections, which has reduced chronic inflammation and later-life mortality rates, particularly from cardiovascular disease, stroke, and cancer. Early-life cohort mortality rate often predicts later-life survival in humans, but such associations could arise from factors other than disease exposure. Additionally, the impact of early-life disease exposure on reproduction remains unknown, and thus previous work ignores a major component of fitness through which selection acts upon life-history strategy. We collected data from seven 18th- and 19th-century Finnish populations experiencing naturally varying mortality and fertility levels. We quantified early-life disease exposure as the detrended child mortality rate from infectious diseases during an individual's first 5 y, controlling for important social factors. We found no support for an association between early-life disease exposure and all-cause mortality risk after age 15 or 50. We also found no link between early-life disease exposure and probability of death specifically from cardiovascular disease, stroke, or cancer. Independent of survival, there was no evidence to support associations between early-life disease exposure and any of several aspects of reproductive performance, including lifetime reproductive success and age at first birth, in either males or females. Our results do not support the prevailing assertion that exposure to infectious diseases in early life has long-lasting associations with later-life all-cause mortality risk or mortality putatively linked to chronic inflammation. Variation in adulthood conditions could therefore be the most likely source of recent increases in adult life span.

Survival and its predictors from age 75 to 85 in men and women belonging to cohorts with marked survival differences to age 75: a comparative study in three Nordic populations

BACKGROUND AND AIMS

While predictors of survival in older people have been examined in depth in a large number of studies, a literature search revealed no cross-national comparative prospective cohort studies on this issue. This study investigated survival and its predictors from age 75 to 85 among three local Nordic populations using survival data on national cohorts as background information.

METHODS

The data were derived from national registers and from samples of 75-year old living in Denmark, Sweden, and Finland. The subjects were invited to take part in interviews and examinations focusing on different domains of health, functional capacity, and physical and social activities.

RESULTS

The proportion of survivors to age 75 was markedly smaller among the Finnish men and women than Danish or Swedish subjects. In the local population no marked differences in survival from age 75 to 85 were observed between the groups of men, while women survived longer than men and longer in Göteborg than in Glostrup or Jyväskylä. Univariate models revealed 12 predictors of survival. In the multivariate models, the significant predictors among men related to physical fitness, whereas among women they pertained to social activities and morbidity.

CONCLUSIONS

Despite great differences in the proportions of survivors to age 75, and excepting the survival advantage of women, only minor differences were present in the subjects' further survival to age 85. In the univariate analyses, many of the factors predictive of survival from age 75 to 85 were the same in the examined populations, whereas in the multivariate analyses differences between the sexes emerged.

An Old Mom Keeps You Young: Mother's Age at Last Birth and Offspring Longevity in Nineteenth-Century Utah

This study analyzes the intergenerational effects of late childbearing on offspring's adult longevity in a population in Utah (United States) that does not display evidence of parity-specific birth control-a so-called natural fertility population. Studies have found that for women who experience late menopause and prolonged reproduction, aging is postponed and longevity is increased. This is believed to indicate female "robustness" and the impact of biological or genetic factors. If indeed there is a genetic component involved, one would expect to also find evidence for the intergenerational transmission of longevity benefits. Our study investigates the relationship between prolonged natural fertility of mothers and their offspring's survival rates in adulthood. Gompertz regression models (N = 7,716) revealed that the offspring of mothers who were naturally fertile until a relatively advanced age lived significantly longer. This observed positive effect of late reproduction was not independent of but conditional upon survival of the mother to the end of her fecundity (defined as age 50). Offspring's relative risks at death beyond age 50 were 6-12 percent lower than those of their counterparts born to mothers who had an average age at last birth. Our results, which account for various early, adult, and later-life conditions, as well as shared frailty, suggest that there is a positive relationship between mother's age at last birth and offspring longevity, and strengthen the notion that age at menopause is a good predictor of this relationship.