A team of researchers based at Tulane University School of Medicine has found that exposure to violence or other traumatic events within the family during childhood can leave lasting marks on stretches of DNA called telomeres. This study adds to the growing body of evidence that stressful home environments can permanently affect chromosomes. The work has been published in the journal Pediatrics.

Telomeres are repetitive sequences of DNA found at the end of chromosomes that act as protective caps, preventing chromosomes from sticking together or being degraded, both of which can lead to cell death. Telomeres can be thought of as a kind of cellular timer as they shorten a little bit every time a cell replicates until they reach a certain limit; after this the cell will no longer replicate. Telomere length has been linked to a variety of diseases and shorter telomeres have been associated with higher risks for heart disease, diabetes, cognitive decline and mental illness, to name a few.

In order to further our knowledge of how adverse events during childhood may negatively impact health, Tulane University researchers investigated the links between exposure to disruptive or violent events and telomere length in youth.

80 children between the ages of 5-15 were recruited in New Orleans and data was gathered on family environment and exposure to traumatic events by interviewing the parents. The team then took samples from the children and analysed telomere length. After controlling for other sociodemographic factors, the team found an association between exposure to family violence or family disruption and telomere length. More specifically, they found that telomere length was significantly shorter in children that were exposed to adverse events within the family such as domestic violence, suicide or incarceration when compared with children in more stable households.

Furthermore, the researchers found differences between girls and boys. In particular, they discovered that these traumatic events were more likely to affect telomere length in girls. They also discovered that there was a protective effect for boys if the mother was well-educated as there was a positive association between telomere length and education of the mother, but this was only apparent in boys under the age of 10.

“Family-level stressors, such as witnessing a family member get hurt, created an environment that affected the DNA within the cells of the children,” lead author Dr. Stacy Drury said in a news-release. “The greater the number of exposures these kids had in life, the shorter their telomeres were- and this was after controlling for many other factors, including socioeconomic status, maternal education, parental age and the child’s age.”

This is the second study published this year which demonstrates that stressful home environments and telomere length are linked. Back in April, a report in PNAS found that children growing up in poor and unstable homes had shorter telomeres than children raised in nurturing families.

According to Drury, this study highlights the fact that the home environment is an important intervention target to reduce the lasting biological impacts of childhood adversity.