Editor's Note: (Daniel Keating is a professor of psychology at the University of Michigan and author of "Born Anxious: The Lifelong Impact of Early Life Adversity -- and How to Break the Cycle," due to be published in April from St. Martin's Press. The opinions expressed in this commentary are his own.)
(CNN) There are new clues that the high levels of stress many people endure every day are taking a deadly toll.
White, working-class Americans are dying in middle age at a rapidly increasing pace, reversing a long-standing trend toward greater life expectancy across all races and social classes, according to a new report from economists Anne Case and Angus Deaton.
Much of this alarming trend comes from "deaths of despair," especially opioid addictions and overdoses, suicide, and alcohol-related diseases. To stem this epidemic, they argue that we need to understand the underlying reasons why this is happening. Case and Deaton make a plausible case that "slow moving and cumulative" social forces -- lack of labor market opportunities and fraying of the accustomed social fabric -- are key explanations. They reject arguments that attribute this trend to income alone or to a decline in virtue.
But an even more basic cause lies hidden at the intersection of psychology and biology -- a widespread stress epidemic that is affecting this group dramatically at the present but threatens all of us unless we soon understand the source of this trend and take steps to address it.
Stress-related disorders and diseases have been on the rise in the whole population for decades, according to data from the Centers for Disease Control and Prevention, including those leading to these deaths of despair, but also to heart disease, obesity, and diabetes.
National surveys by the American Psychological Association that also capture how stressed, anxious and overwhelmed we feel show a similar increasing pattern. And it shows up in our bodies, even before we get sick or start down the many roads to self-harm.
A recent study by the Hamilton Project looked at the "physiological stress load" in the US using biological markers tied to cardiovascular, kidney and liver function to create a stress load index. This physical stress load, a precursor to many diseases, has increased in striking fashion since the late 1970s, and it is getting worse as each new age group enters adulthood.
We should see this increase in mortality for what it is -- a leading indicator of what could be in store for many of us. What social forces are producing the broader stress epidemic, and how do they "get under the skin" to cause long-term damage? One major clue comes from a closer look at the stress load index.
It has increased for everyone, but with marked inequality -- it has risen more sharply for those with fewer social and economic resources but also more for the middle class compared to the well off. There is a clear line that connects increasing inequality in income and opportunities, to increases in stress and mortality that hits some groups earlier than others.
A central biological pathway is from excess cortisol -- the fight-or-flight hormone -- that characterizes being over-stressed for long periods of time. This "stress dysregulation" leads to risky health decisions, like addiction or overeating, and directly to many health problems linked to excess cortisol.
Why are white, working-class Americans showing the earliest effects? Surely African-Americans and Hispanics have been experiencing inequality at equal or higher levels over these same decades. The key lies in different starting points in perceptions of control -- stress is largely a psychosocial phenomenon, though, of course, material deprivation also plays a role.
Minorities have gained some ground materially, in relative terms, over recent decades, but they also did not start with an assumption of being in control in the wider society. Losing a sense of control that you believed you had, whether real or not, justified or not, creates stressful dislocations.
We have seen this pattern before. In the disintegration of the Soviet Union in the 1990s, the group that saw itself as having substantial control -- middle-aged Russian men in particular -- experienced a similar loss of control, economically and in terms of cultural identity as the "socialist vanguard." They also died younger, suffering dramatic increases in early mortality.
If we understand what is actually happening -- socially, psychologically and biologically -- we can see that this effect is not going to be limited to just one group in the future. My colleagues and I have reported a pattern of increasing inequality being tied to worsening population outcomes -- not for mortality, but for the health, achievement and social engagement of adolescents in rich Western countries. But what we also found was that this was not inevitable.
Countries (Austria, Denmark, France, Sweden and others) that controlled income inequality and maintained investments in human development -- such as early childhood and parenting support, education, and social safety nets in health care and unemployment -- did not experience these increasing problems in adolescent and youth development.
Slow-moving and cumulative social forces "get under the skin" early in life and can show up decades later in morbidity and mortality. The risk is magnified in light of very recent research showing that high levels of stress experienced by expectant mothers or by babies can make fundamental biological changes in infancy -- through what are known as epigenetic changes, which alter how genes work -- that can endure over a lifetime.
This burden of stress dysregulation in young Americans from early life adversity amplifies the stress epidemic by making more of us vulnerable, and by increasing the total amount of ambient stress we all experience everyday in our schools, our workplaces, our social media, on our highways, in our malls -- in effect, throughout our communities.
Increasing inequality and decreasing investment in human development place all of us at risk -- a stressful recognition itself in the current political environment where there is the potential for going even further in the risky direction. Resisting these trends is essential to health, because the consequences will show up for all of us for decades to come.