We might not be able to remember every stressful episode of our childhood.
But the emotional upheaval we experience as kids — whether it's the loss of a loved one, the chronic stress of economic insecurity, or social interactions that leave us tearful or anxious — may have a lifelong impact on our health.
In fact, a study published this week in the Journal of the American College of Cardiology indicates that emotional distress during childhood — even in the absence of high stress during adult years — can increase the risk of developing heart disease and metabolic disorders such as diabetes in adulthood.
"We know that the childhood period is really important for setting up trajectories of health and well-being," explains Ashley Winning, an author of the study and postdoctoral research fellow in social and behavioral sciences at the Harvard T.H. Chan School of Public Health.
To assess the connection between childhood stress and the risk of disease, Winning and her colleagues analyzed data from the 1958 British Birth Cohort Study, a long-running study that documented the diets, habits and emotional health of thousands of British children born during the same week that year.
As the children entered school, the classroom became the laboratory for observation.
"Teachers collected a lot of information — assessing signs and symptoms of distress," Winning explains. "The teachers were checking off [answers to questions such as]: 'Was this child tearful or sad?' " Teachers completed a 146-item assessment.
Teachers evaluated each child at ages 7, 11 and again at 16. After that, as the participants grew older they completed their own assessments of the stress in their lives at ages 23, 33, and 42.
When the participants turned 45, they underwent a biomedical assessment to measure markers of metabolic and cardiovascular health — as well as immune function.
Using these data from 6,714 participants, Winning and her colleagues analyzed the relationship between stress and the risk of various chronic diseases.
"Not surprisingly, those with persistent distress — so, both in childhood and adulthood — had the highest risk," Winning says.
But here's the surprise: Even the adults who had lower distress levels were at higher risk of chronic illness if they had experienced higher levels of distress during childhood.
"It's very interesting that early-life experiences seemed to be such an important predictor [of disease risk]," says Aric Prather, a research psychologist in the department of psychiatry at the University of California, San Francisco. Though the study can measure only correlation, not causation, it dovetails with other findings. And the large number of people it tracked for many decades make its findings worth paying attention to, scientists say — and worth following up on with other kinds of research.
Prather, who also studies the links between psychology and immunity, says the mechanisms by which early-life experiences influence health are complicated and not yet completely understood.
"There's certainly growing evidence that there may be some biological embedding that takes place," Prather says.
In other words, it's possible, he says, that when people experience early-life stress "it actually changes something about them biologically." Stress may influence how genes get switched on or off, for instance, or may initiate some other physiological effects.
There's still a lot to learn, but this much is clear, Prather says: "The mind and the body are much more tightly related than we used to believe."
ARI SHAPIRO, HOST:
The things that happen to us in childhood - how much stress we experience growing up - could be a predictor of heart disease and metabolic disorders later in life, things like Type 2 diabetes and stroke. NPR's Allison Aubrey reports on a study just published in the Journal of the American College of Cardiology.
ALLISON AUBREY, BYLINE: Fifty years ago, researchers in Great Britain began studying a group of children who were just entering preschool. The idea was to gather as complete a picture as possible about everything going on in these kids' lives, from their diets and habits to their emotional health. Researcher Ashley Winning of the Harvard School of Public Health says to get the best measures, especially of mental well-being, a lot of the observations were recorded right in the classroom.
ASHLEY WINNING: It's actually teacher reported, so teachers collected a lot of information assessing the signs and symptoms of distress. So they're checking off, you know, was this child tearful or sad?
AUBREY: Each child was assessed multiple times during their school years, and then as the children become adults, the teachers' assessments of emotional health gave way to their own accounts of the stress in their lives. Then finally, at age 45, some 7,000 of the original participants agreed to undergo a battery of physical tests. Doctors measured their metabolic and cardiovascular health and their immune function. Ashley Winning and her colleagues took all of this data and they analyzed the relationship between stress and disease.
WINNING: Not surprisingly, those with persistent distress - so in both childhood and adulthood - had the highest risk.
AUBREY: But Winning says what she did not expect is this - even the adults who had low stress levels were at significantly higher risk of disease if they'd had bouts of high stress between the ages of 7 and 16. Aric Prather, a psychologist at UCSF, says the results are surprising.
ARIC PRATHER: It was very interesting that early life experiences seem to be such an important predictor as well.
AUBREY: He says it's possible that stress early in life could influence how genes get switched on or off or have some other physiological effects.
PRATHER: There's certainly growing evidence that there may be some biological embedding that takes place, that individuals who experience early life stress, it actually changes something about them biologically that we don't quite understand yet.
AUBREY: Prather says there's a lot to learn, but what's clear is this.
PRATHER: The mind and the body are much more tightly related that we used to believe.
AUBREY: And promoting good emotional health may help prevent disease.
Allison Aubrey, NPR News. Transcript provided by NPR, Copyright NPR.