Cohort Studies

April 15-16, 2016
Dora Costa of University of California, Los Angeles, Organizer

Daniel W. Belsky, Duke University

The Genetics of Success: How SNPs Associated with Educational Attainment Relate to Life-course Development

Previous genome-wide association analysis (GWAS) of >100,000 individuals identified molecular-genetic predictors of educational attainment. Belsky and coauthors undertook in-depth life-course investigation of the polygenic score derived from this GWAS using the four-decade Dunedin Study (N=918). There were five main findings. First, polygenic scores predicted adult economic outcomes over and above completed education. Second, genes and environments were correlated; children with higher polygenic scores were born into better-off homes. Third, polygenic scores predicted children' adult outcomes net of social-class origins; children with higher scores tended to be upwardly-socially-mobile. Fourth, polygenic scores predicted behavior across the life-course, from learning to talk earlier to acquiring reading skills more quickly, through geographic mobility and mate choice, on to financial planning for retirement. Fifth, polygenic-score associations were mediated by psychological characteristics including intelligence, self-control, and interpersonal skill. Effects were small. Factors connecting DNA sequence with life outcomes may provide targets for interventions to promote population-wide positive development.

Caleb Finch, University of Southern California

Air Pollution in Brain Development & Aging

Adrian Adermon, Uppsala University; Mikael Lindahl, University of Gothenburg; and Mårten Palme, Stockholm University

Dynastic Human Capital, Inequality and Intergenerational Mobility

Adermon, Lindahl, and Palme study the importance of the extended family — or the dynasty — for persistence in human capital and inequality across generations. They use data including the entire Swedish population, linking four generations. This data structure enables the authors to — in addition to parents, grandparent and great grandparents — identify aunts and uncles and their spouses, as well as parents' cousins and parents' aunts and uncles. The researchers use three different indicators of social status — years of schooling, average earnings and an index of occupational status. The results suggest that both the inclusion of several indicators as well as the dynastic "group effect" are important, and that traditional intergenerational persistence estimates miss about half the persistence across generations estimated by the extended model.

Günther Fink, Harvard University; Atheendar Venkataramani, Massachusetts General Hospital; and Arianna Zanolini, Centre for Infectious Disease Research in Zambia

Do It Well or Not at All? Malaria Control and Child Development in Zambia

Fink, Venkataramani, and Zanolini assess the impact of recent large-scale anti-malaria efforts on child development in Zambia. Unlike the interventions examined in prior work on the human capital effects of malaria, the Zambian efforts led only to temporary reduction in exposure to the disease: in the most highly affected areas, parasite prevalence declined markedly in the two years after the beginning of the program scale-up, but resurged soon thereafter in highly endemic areas. Comparing cohorts born before and after the campaign launch, the researchers find that children with initially low but resurgent malaria exposure perform more poorly on cognitive tests, and no better on anthropometric and executive functioning, than children from the same areas with high exposure in the first two years, and varying exposure after age 2. These findings are not explained by mortality or fertility selection, changes in parental investment, or crowd-out of other health services and behaviors. Instead, the authors hypothesize (and provide suggestive evidence) that the adverse results are driven by children's failure to form partial immunity to the disease in the first two years of life, making them more vulnerable to more severe illness when faced with resurgent disease. The results suggest important tradeoffs between environment-driven early life developmental improvements and early life immunity development in models of human capital formation. They also suggest that sustained programmatic investment throughout childhood is critical to avoid potentially large adverse consequences of exposing non-immune populations to resurgent infectious diseases.

Andreas Georgiadis, University of Oxford

The Sooner the Better but It's Never Too Late: The Impact of Nutrition at Different Periods of Childhood on Cognitive Development

Although, it has been argued that undernutrition and its consequences for child development are irreversible after the age of 2 years, the evidence in support of these hypotheses is inconclusive. This paper investigates the impact of nutrition at different periods from conception to age 8 years on cognitive achievement at age 8 years using data from Ethiopia, India, Peru, and Vietnam. In order to address estimation problems Georgiadis develops a conceptual framework and uses exogenous variation in nutritional status arising from weather shocks. Results suggest that undernutrition in utero and infancy and its impact on cognitive development can be reversed through nutrition and cognitive skills investments in later periods of childhood and that the direction of parental investment responses to changes in the child's nutritional status depends on the timing of undernutrition.

Pietro Biroli, University of Zurich

Genetic and Economic Interaction in the Formation of Health: The Case of Obesity

Small genetic differences at birth confer a comparative advantage in health and human capital formation, and can lead to substantial inequality in long term social and economic outcomes. Biroli develops a structural model of health and human capital formation illustrating the dynamic interaction between genetic inheritance and investments in health over the life cycle. Genetic heterogeneity across individuals can change the utility cost of investments and the production function of health, shifting the incentives to invest in healthy habits. Focusing on Body-Mass-Index (BMI) as a measure of poor health, the author considers physical activity and food intake as investments in health, and evaluates their interaction with specific variants in FTO and other genes associated with BMI in Genome-Wide Association Studies. Applying this model to two different datasets, one of British adolescents and one of U.S. adults, Biroli finds that Gene-Environment interaction plays a pivotal role in the evolution of BMI. Food intake has a stronger impact on BMI for those individuals with a particular genetic makeup, and yet they tend to display a higher demand for food. The association of variants in the FTO gene with the hypothalamic regulation of food intake gives a biological foundation to the observed differences in healthy investments. This analysis provides an economic framework of health and human capital formation that integrates recent findings in genetics and molecular biology and sheds light on the interdependence between genes and economic choices of investment.

Itzik Fadlon, University of California at San Diego and NBER, and Torben Heien Nielsen, University of Copenhagen

Intra-Household Dependencies in Health: Evidence from Spousal Mortality and Severe Health Shocks

Sok Chul Hong, Seoul National University

The Socioeconomic Gradient in the Inheritance of Longevity: A Study of American Genealogies

Using American genealogical records on cohorts born in 1845-1884 and their parents, Hong and Park study the inheritance of longevity across two generations in mid-19th-century America. They find that the level of inheritance was intensified by socioeconomic status in children's early life, which is measured by father's occupational income score. This pattern is estimated more substantially among those born in unhealthy urban states than in rural states. The study suggests that better socioeconomic conditions helped to avoid the risk of premature death in unhealthy areas, which strengthened the intergenerational transmission of longevity.

Achyuta Adhvaryu, University of Michigan; Teresa Molina, University of Southern California; Anant Nyshadham, Boston College; and Jorge A. Tamayo, Central Bank of Colombia

Helping Children Catch Up: Early Life Shocks and the Progresa Experiment

Can investing in children who faced adverse events in early childhood help them catch up? Adhvaryu, Molina, Nyshadham, and Tamayo answer this question using two orthogonal sources of variation — resource availability at birth (local rainfall) and cash incentives for school enrollment — to identify the interaction between early endowments and investments in children. They find that adverse rainfall in the year of birth substantially decreases grade attainment, post-secondary enrollment, and employment outcomes. But children whose families were randomized to receive conditional cash transfers through the Mexican government's Progresa policy experiment experienced a smaller decline: each additional year of program exposure mitigated more than 20 percent of early disadvantage. Moreover, the researchers show that Progresa's impacts were heavily concentrated on children who faced poor birth environments; children born during normal rainfall periods essentially showed half the gains in education and no gains in employment due to the cash transfers.

Marcella Alsan, Stanford University and NBER, and Marianne H. Wanamaker, University of Tennessee and NBER

Tuskegee and the Health of Black Men

For forty years, the Tuskegee Study of Untreated Syphilis in the Negro Male passively monitored hundreds of adult black males with syphilis despite the availability of effective treatment. The study's methods have become synonymous with exploitation and mistreatment by the medical community. Alsan and Wanamaker find that the historical disclosure of the study in 1972 is correlated with increases in medical mistrust and mortality and decreases in outpatient physician interactions for black men. Blacks possessing prior experience with the medical community, including veterans and women, appear to have been less affected by the disclosure. The researchers' findings relate to a broader literature on how beliefs are formed and the importance of trust for economic exchanges involving asymmetric information.

Andrew Noymer, University of California at Irvine, and Natalie A. Rivadeneira, Emory University

"You've Come a Long Way, Baby: The Convergence in Age Patterns of Lung Cancer Mortality by Sex, United States, 1959-2013

Noymer and Rivadeneira analyze lung cancer mortality by age and sex in the United States from 1959–2013. Mortality patterns by age are a very good fit to a quadratic-Gompertz model, i.e., log mortality rates are quadratic by age, peaking above age 70. These models bring sex differences in lung cancer into sharp relief. With a little additional historical data on sex differences in tobacco use, the models paint a clear picture of behavior-led convergence in lung cancer mortality by sex. In fact, it is uncanny just how well the changes in sex differences in tobacco use are reflected by the quadratic-Gompertz mortality models. While male lung cancer death rates, per se, are statistically-significantly higher than females throughout the data set, the shape of the mortality curves has converged dramatically. Since 1983, the sexes have had statistically-indistinguishable shapes of their quadratic-Gompertz mortality curves. Female lung cancer mortality patterns have shown a transformation from a non-smoking to a smoking pattern.

Diane Lauderdale, University of Chicago

Are Americans Sleeping Less Then They Used To? Evidence for Adults and Adolescents

Victor Lavy, University of Warwick and NBER; Analia Schlosser, Tel Aviv University; and Adi Shany, Hebrew University

Out of Africa: Human Capital Consequences of In Utero Conditions (NBER Working Paper No. 21894)

This paper investigates the effects of environmental conditions during pregnancy on later life outcomes using quasi-experimental variation created by the immigration of Ethiopian Jews to Israel on May 24th, 1991. Children in utero prior to immigration faced dramatic differences in medical care technologies, prenatal conditions, and prenatal care at the move from Ethiopia to Israel. One of the major differences was adequacy of micronutrient supplements, particularly iodine, iron and folic acid. Lavy, Schlosser, and Shany find that children exposed in an earlier stage of the pregnancy to better environmental conditions in utero have two decades later higher educational attainment (lower repetition and dropout rates and higher Baccalaureate rate) and higher education quality (achieve a higher proficiency level in their Baccalaureate diploma). The average treatment effect the researchers estimate is driven mainly by a strong effect on girls. They find however, no effect on birth weight or mortality for girls.

Leah Platt Boustan, University of California at Los Angeles and NBER; Katherine Eriksson, University of California at Davis and NBER; and Philipp Ager, University of Southern Denmark

The Effect of Fathers' Wealth on Sons' Adult Outcomes in the Nineteenth Century: Evidence from the Civil War

Martha Bailey, University of Michigan and NBER

Longitudinal, Intergenerational Family Electronic Microdata (LIFE-M) Project

Steven Lehrer, Queen's University and NBER; Hans-Martin von Gaudecker, Bonn University; and Mårten Palme, Stockholm University

Gender Differences in Health Sector Utilization: New Evidence from Exploring Variation across Cohorts and the Lifecycle in Sweden

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