Playing the Long Game: Epigenetics and Public Health

By Seán Finan

Good investing takes time, foresight and patience. You have to thoughtfully spend now for a big return in ten years. But when it comes to investments in public health, everybody wants to make a quick and easy buck. I’ve written before about the need for more emphasis on preventive care over “heroic medicine”: it costs less, it’s easier to administer and it leads to better outcomes. But fully realizing the potential of preventive care and public health initiatives takes more than vaccines and check-ups. The government could invest in an unlimited buffet of hospital examinations and laboratory tests for all, but if people can only afford food that leaves them obese and diabetic or if they live in neighborhoods where crack dens and meth labs outnumber the schools, the investment is not going to pay off. Addressing the social determinants of health has incredible potential to improve outcomes on a population level.

Efforts are already being made. The government aims for “Health in All Policies” by promoting holistic education programs for poor youths and funding better food in stores in neglected communities. Other initiatives focus on fighting food insecurity among families or homelessness among pre and post natal mothers. The topic was covered well in this article from the Kaiser Family Foundation. They break the social determinants of health into the broad categories of social, economic and environmental factors. Things like economic stability, neighborhood and physical environment, education, food and social context play a massively underappreciated role in health outcomes. The article contains a graphic on the impact of different factors on the risk of premature death. Apparently, healthcare has the smallest impact at 10%. Individual behaviors carry the biggest single impact at 40%. The social and environmental factors that the article focuses on contribute 20%. The last factor was genetics, at 30%. As I was reading, I remembered seeing this article on epigenetics and it struck me that the separation of genetics from behavior and environmental factors might be a little artificial.

The science of epigenetics is young and still poorly understood, but the basic theory can be put simply enough. DNA is like a collection of blueprints and instruction manuals for building a body. But not every blueprint in the collection is used. Some genes are expressed; some remain dormant. The study of epigenetics has shown that some can be “switched” on or off: you can be born with a dormant gene but something might trigger its expression later in life. Many of these changes are not for the better. For example, through an epigenetic change, you can develop an increased likelihood of diabetes or even schizophrenia. What triggers these switches? What “turns on the diabetes gene”? Primarily, social and environmental factors.

Identical twins that are separated at birth are often the perfect subjects to study. Despite having exactly the same DNA and, often, an astonishing number of shared characteristics and traits, the lifestyles and life experiences of twins will often lead to markedly different health outcomes. The longer these twins spend apart, the more pronounced these differences become. But epigenetics can reach across generations.

There is clear evidence in animal models that nutrition and stress in pregnancy can impact the health of future generations. Studies have shown that feeding pregnant mice a diet short in certain essential nutrients makes their pups genetically obese, cancer-prone and bright yellow. Observational studies have seen similar effects in humans. For example, this article links pre- and post-natal homelessness to poor health outcomes in children. The causal link between post-natal homelessness and poor health is fairly intuitive. Life on the streets damages the health of the hardiest of adults, never mind a newborn. But the elevated adrenaline and cortisol levels flowing through a stressed, homeless pregnant woman might trigger genetic changes in her child that manifest as disease in later life.

Maybe this is nothing we didn’t know already. Pregnant and soon-to-be-pregnant women have always been advised to “eat for two” and live as healthily as possible, “for the sake of the baby”. But there is some evidence that the sins of the father and the grandfather and the great-grandfather might be felt by the great-grandson.

There is some, albeit limited evidence that genes that get “turned on” in one generation can remain turned on for several generations. One study from Sweden suggests that if your grandfather lived through a period of famine in his early life, you might inherit epigenetic changes that make you less likely to die of cardiovascular disease. On the other hand, if he lived through a period of food abundance in early life, you might be more prone to diabetes. The validity of this study is highly debated, but let’s just assume, for a moment, that the science is good. That means that the environment that my grandmother lived in can have an impact on my health today. I was at a workshop recently where it was speculated that epigenetics might go some ways towards explaining the fact that black mothers and children have a higher mortality rate than white mothers and children, even when you control for poverty level. Bluntly put, the fact that one child’s great-grandmother was a slave and the other child’s great-grandmother was a slave master might mean that the first child dies sooner, even though both mothers now work on Wall Street.

What does this mean for efforts to revolutionize American health by focusing on the social determinants of health, rather than healthcare? It means that we need to be patient. Really, really patient. We may not see any return on our investments until the epigenetic effects of poverty and poor nutrition wash out over generations. But the results will be worth it. To quote Warren Buffett (possibly the most successful investor ever),

“someone is sitting in the shade today because someone planted a tree a long time ago.”


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