Scientists have long known that childhood trauma can have a far-reaching impact on people’s later physical and mental health. Now a new study published Monday in Proceedings of the National Academy of Sciences suggests that at least one reason for this impact may involve the tiny parts of our cells that influence the aging process.

Researchers examined data taken from the Health and Retirement Study, a long-running project aimed at detailing people’s health as they enter their golden years. They studied the saliva DNA samples of more than 4,000 people over the age of 50, specifically looking at the length of their telomeres, the bits of DNA and protein at the end of our chromosomes known to play a role in how we age. They found that after accounting for other factors, people who repeatedly experienced stressful life events — especially during childhood — were more likely to have shortened telomeres than those who didn’t, indicating these individuals’ cells had aged faster and left them more vulnerable to a variety of chronic and age-related diseases such as cancer.

“This study suggests that the shadow of childhood adversity may reach far into later adulthood in part through cellular aging,” concluded the authors.

Telomeres are partially responsible for keeping our cells’ health in check. Every time our cells divide, there’s a little bit of incidental damage inflicted on our DNA. But telomeres help absorb much of this damage, albeit at the cost of slowly shrinking in length. Eventually this process wears telomeres down to the point where cell mutations become much more common and our bodies are no longer able to stay as healthy as before.

In the current study, there were certain kinds of stress more associated with telomere damage than others — in particular, traumatic and psychologically stressful events like parental abuse compared to financial stress. When the researchers focused on people’s childhoods, they found that each additional stressful event amounted to a 11 percent greater chance of shorter telomeres. Overall, people with high levels of lifetime adversity had a 6 percent higher chance of shorter telomeres.

Research elsewhere has shown that many environmental factors can speed along the shortening of telomeres, from diseases like HIV to sedentary behavior, so the idea that childhood stress can as well isn’t far-fetched. But lead author Dr. Eli Puterman, director of the Fitness, Aging & Stress Lab at the University of British Columbia in Vancouver, Canada, is cautious about his team’s results, noting that they only show a correlation, not a direct cause-and-effect relationship. And not everyone who experienced childhood pain went on to have shorter telomeres.

"This doesn't mean that every single person has short telomeres," Puterman told HealthDay. "It just means there's an increased risk."

Equally uncertain is whether there’s anything we can do to reverse telomere damage right now. Some research has shown that the adoption of healthy habits like exercising and dieting can possibly restore telomere length or slow its decline, but it isn’t conclusive. Even if we could, though, the science behind how exactly telomeres affect human health and what causes telomeres to shrink is still in its earliest stages.

In any case, you hardly need to prove that childhood trauma causes shorter telomeres to know that our earliest experiences can weigh heavy on our minds and bodies long after they’ve come and gone.

Source: Puterman E, Gemmill A, Karasek D, et al. Lifespan adversity and later adulthood telomere length in the nationally representative US Health and Retirement Study. Proceedings of the National Academy of Sciences. 2016.