At a Glance
Early-Life Determinants of Cognitive Functioning, Health, and Mortality
Mikko Myrskylä, Kieron Barclay, Rasmus Hoffmann, Nicolas Todd, Pekka Martikainen (MPIDR / University of Helsinki, Finland); in Collaboration with Anna Baranowska-Rataj (Umeå University, Sweden)
A growing body of work has shown that early-life conditions are associated with a variety of outcomes throughout the life course, from cognitive development to educational and socioeconomic attainment through to health and mortality. Studies examining the long-term effects of early-life conditions typically define “early life” very broadly, and the term “early-life conditions” may encompass factors such as family and environmental conditions experienced during childhood, perinatal health, or even in utero exposures. Evidence from natural or quasi-natural experiments suggests that the association observed between some adverse early-life conditions and later-life outcomes is causal. However, unanswered questions remain, including the degree to which early-life effects might be moderated by contextual factors and the extent to which any associations are explained by mediating pathways.
To develop our understanding of early-life factors affecting later-life outcomes, we employ high-quality data from Finnish and Swedish administrative population registers and a range of advanced statistical techniques. To try and disentangle the effects of early-life exposures on later-life outcomes from shared factors that may confound the associations, we use comparisons of sibling fixed effects. We also estimate sibling intra-class correlations (ICC) as summary measures of all early-life and familial influences. The outcomes that we examine range from educational achievements in school, such as high school grade point average (GPA), to all-cause and cause-specific mortality.
This project has already yielded a number of key results. These include the finding that premature births do not generally seem to negatively impact educational achievements after taking account of the degree of prematurity and adjusting for shared factors in the family of origin; it is only children born extremely preterm who have worse outcomes, and extreme prematurity in terms of gestational age corresponds almost exactly to a key period of in utero brain development during gestation. However, even the outcomes of children born extremely preterm can be substantially improved if they attend the highest performing schools, illustrating the importance of moderating contextual factors. Since children born extremely preterm are only a small fraction of preterm births, the population-level impact of premature births on later-life outcomes is likely to be very limited.
In other work, we have shown that adverse social circumstances during childhood are typically associated with an excess of cause-specific mortality of about 10–30% However, these associations are almost fully attenuated by adjustment for mediating dimensions of socioeconomic attainment in adulthood. Early-life influences on mortality from external causes, and particularly those related to home ownership and family type, have grown over time. However, we have also found that the influence of the family of origin on long-term outcomes is only explained to a small degree by observed factors such as demographic and socioeconomic factors, including the region, the number of siblings, the native language, parents’ education and occupation, and individual income, occupation, tenancy status, and education. These factors only account for 10–25% of the familial influence on mortality, meaning the remainder is unobserved, and this demands further work on this topic.
Aging, Mortality and Longevity, Family Behavior, Health Care, Public Health, Medicine, and Epidemiology, Life Course
Finland, Sweden, United Kingdom, USA
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