(Reuters Health) - The loss of a father due to death, divorce or jail is associated with children having shorter caps on the ends of their chromosomes, according to a study that points to a possible biological explanation for health problems often encountered by kids with absent dads.

The protective caps known as telomeres shrink with age, and are also thought to erode with extreme stress.

At age 9, kids who had lost a father had 14 percent shorter telomeres than children whose dad was still involved in their lives, researchers report in Pediatrics. Death had the biggest impact, and the association was stronger for boys than for girls.

“While we know that disparate stressors - smoking, maltreatment, intense caregiving, etc - are associated with shorter telomeres, the biological link is not well established and is the subject of investigation in several labs,” said senior study author Dr. Daniel Notterman, a molecular biology researcher at Princeton University in New Jersey.

“It is plausible to consider that children who have stress-induced telomere shortening may be at risk for future health problems, but many other factors play a role in a person’s adult health and lifespan,” Notterman said by email.

The loss of a father is widely known to impair a child’s physical and psychological functioning, and the connection between absent dads and health problems for kids is well documented, researchers note. However, less is known about the exact biological causes of medical issues kids with absent dads can encounter.

Telomeres shorten each time a cell divides. Once telomeres are too short, cell growth stops, which is why their length is considered a potential indicator of cellular aging and overall health.

Some previous research has linked shorter telomeres to an increased risk of a variety of chronic health problems in adults, including heart disease and cancer.

For the current study, researchers examined data on family structure and tests of telomere length from saliva samples for 2,420 kids in 20 large American cities.

When a father died, children had 16 percent shorter telomeres than kids with a dad still in their life, the study found.

Losing a dad to incarceration was associated with 10 percent shorter telomeres, while a father absent because of separation or divorce was linked to 6 percent shorter telomeres.

The impact of missing fathers on telomere length didn’t appear to differ by race or ethnicity.

Boys with an absent dad, however, were more vulnerable to shorter telomeres than girls, particularly if boys lost their father before age 5, the study also found.

Researchers also looked at whether certain alleles, or versions of specific genes, might influence the odds of an absent dad being associated with shorter telomeres. Differences in gene variants related to levels of serotonin, a brain chemical responsible for mood, may partially explain why some kids with absent dads are more likely than others to have shorter telomeres, the researchers conclude.

The study wasn’t a controlled experiment designed to prove whether or how absent dads directly contribute to shorter telomeres in kids or cause any specific health problems, the authors note. It’s also possible that a variety of factors not examined in the study, such as mothers’ parenting quality, might influence whether kids develop shorter telomeres after the loss of a father.

Even so, since shorter telomeres are a marker of cellular aging, the study results suggest a biological link between early adversity and a risk for a range of chronic physical illnesses, said Dr. David Brent, chief of child and adolescent psychiatry at the University of Pittsburgh Medical Center.

“This is important,” Brent said, because there is evidence that meditation can help buffer the effects of adversity. “So that for individuals with exposure to early adversity, such interventions could in theory actually prevent or attenuate chronic illnesses,” Brent, who wasn’t involved in the study, said by email.

With death in particular, counseling both mothers and children can help prevent the loss of a father from impacting kids’ health, Brent added. Previous research has shown just a dozen sessions focused on parenting skills and child coping can encourage better discipline practices and the open expression of grief.

“There is evidence that strengthening families can buffer against the effects of the death of a parent,” Brent said.

SOURCE: bit.ly/2uFNj55 Pediatrics, online July 18, 2017.