Could the speed at which people age be affected by economic stress their mothers experienced before they were even born? A new study by Assistant Professor Lauren Schmitz that follows people who were born during the Great Depression shows that early-life exposure to poor economic conditions is associated with accelerated aging later in life. According to the study, the in utero period is particularly sensitive to economic shocks, including declines in wages and employment, that can result in increased risk of early death and decline decades later. Published in the Proceedings of the National Academy of Sciences (PNAS), the study followed 832 adults in the U.S. Health and Retirement Study (HRS) who were born in the 1930s during the worst economic downturn in U.S. history. Findings show that exposure to the changing economic conditions during that decade had lasting impacts.
The study measures how quickly the people in the study aged biologically by examining two epigenetic aging signatures that predict mortality risk and physiological decline. Aging is characterized by the gradual accumulation of cellular damage, leading to physiological deterioration, loss of function, and increased vulnerability to death. Causal studies involving epigenetic programming in humans—the idea that exposure to specific conditions during critical periods in early life change a person’s development and have long-lasting effects in adulthood—are rare and are often unable to separate in utero effects from the effects of conditions after birth.
As Schmitz explains, “we were able to use a quasi-natural experiment to conduct this study because we had a unique opportunity to link information on macroeconomic conditions during the Great Depression with epigenetic data that was profiled at older ages in the HRS. As the cost of epigenomic profiling falls and researchers are increasingly able to link data on adverse exposures with biologically sensitive indicators of aging, it’s becoming more apparent that disparities in health between individuals begin developing before we’re even born.” Schmitz’s co-author is American University’s Valentina Duque (Public Administration and Policy).
The authors focused on the period of the Great Depression because of the magnitude of exposure to poor economic conditions, and because there were few social welfare programs at that time to counteract the financial devastation Americans experienced. Additionally, women lacked access to prenatal vitamins and other nutritional supplements that are available to women today. The idea that aging later in life is linked to in utero programming has important implications for the development of early-life interventions that could postpone age-related issues and significantly extend healthy life span.
“The adverse economic conditions that people are exposed to before birth and at early ages shouldn’t affect how long they live,” says Schmitz. “Our findings suggest that social programs that provide support for pregnant women and families, particularly during tough economic times, may improve the health of children not just in the short run but throughout their life. As our population ages, we need to start thinking about the costs and benefits of social programs and access to health care during these sensitive periods of development not just in terms of their short-term impacts on childhood health but also in terms of the positive benefits they may engender at older ages when health care costs are at their highest.”