Researchers have found that violence in the lives of children can cause changes in their DNA equivalent to seven to 10 years of premature aging.
Scientists measured this cellular aging by studying the ends of children's chromosomes, called telomeres.
Telomeres are DNA sequences that act like the plastic tips on shoelaces, which prevent the DNA in chromosomes from unraveling. Each time a cell divides, the telomeres become shorter until a cell dies when it can't divide anymore, reports Liz Szabo for USA Today.
Idan Shalev, a post-doctoral researcher in psychology and neuroscience at the Duke Institute for Genome Sciences & Policy
and lead author of the study in today's Molecular Psychiatry
says, "This is the first time it has been shown that our telomeres can shorten at a faster rate even at a really young age, while kids are still experiencing stress."
The researchers analyzed DNA samples from twins at ages 5 and 10 and compared telomere length to three kinds of violence: domestic violence between the mother and her partner, being bullied frequently, and physical maltreatment by an adult. Moms were also interviewed when kids were 5, 7, and 10 to create a cumulative record of exposure to violence.
The research team plans to further explore the new findings by measuring the average length of telomeres in the twins after they become adults. They'll also repeat the study in a second, older group of 1,000 individuals in the Dunedin Study, who have been under observation since their birth in the 1970s in New Zealand.
The study suggests that children exposed to such stresses could be expected to develop age-related diseases such as heart attacks or memory loss, seven to 10 years earlier than their peers.
Whether or not these changes are reversible is not clear. Shalev and colleagues plan to study the children for longer periods of time to see what happens later on in life.
"Research on human stress genomics keeps throwing up amazing new facts about how stress can influence the human genome and shape our lives," said Caspi, the Edward M. Arnett Professor of Psychology and Neuroscience.
"The study confirms a small-but-growing number of studies suggesting that early childhood adversity imprints itself in our chromosomes," says Charles Nelson, a professor of pediatrics and neuroscience at Harvard Medical School.
In a 2011 study, Nelson and colleagues found shorter telomeres in Romanian children who had spent more time in institutions, compared with children sent to foster care.
Nathan Fox, a professor of human development at the University of Maryland and co-author of the 2011 paper explains, "We know that toxic stress is bad for you. This paper provides a mechanism by which this type of stress gets 'under the skin' and into the genes."
"An ounce of prevention is worth a pound of cure," said Terrie Moffitt, study co-author, "Some of the billions of dollars spent on diseases of aging such as diabetes, heart disease and dementia might be better invested in protecting children from harm."