Abused Children Age Prematurely

By Margarita Nahapetyan

Children, who are exposed to multiple instances of early-life violence and abuse, age fast on a cellular level, experiencing wear and tear to their DNA, found a new study by North Carolina's Duke University scientists.

The study results indicate that chromosomes of kids who were exposed to domestic violence, bullying or physical abuse by an adult, showed signs of biological aging. The findings may help explain now why abused kids are at greater risk of mental and physical disorders when they grow up. Despite the fact that childhood stress has long been associated with health problems, this research appears to be the first to link childhood stress and accelerated biological aging.

According to Idan Shalev, a postdoctoral scientist at Duke University and a principal author of the research, these children are much older than they are supposed to be, and that if the cellular aging is not prevented, the kids would be at greater risk for premature death. To determine the exact dimensions of cellular aging, Shalev and his team looked at a portion of DNA known as telomeres. Telomeres are sequences of DNA that are found on the tips of chromosomes which keep DNA from unraveling. If the telomeres are damaged or shortened, it can be a signal of all kinds of different diseases.

Previous investigations have demonstrated that adults who experienced abuse or bullying in childhood were more likely to have shorter telomeres when compared to those who lived in non-violent environment. However, those investigations could not determine the exact cause for the shortened telomeres, whether it happened because of childhood stress or because of subsequent adult health issues that resulted from that stress.

To find out which exactly is the case, Shalev and his colleagues started a research that looked not backward, but ahead. They took DNA samples from 236 kids (118 pairs of identical twins) who were born in Britain between 1994 and 1995. All of the children provided DNA samples through cheek swabs at age 5 and age 10. The experts thoroughly measured and analyzed telomeres in tens of thousands of cells from each kid, in order to establish an average length of telomere.

In addition, the team carried out series of interviews with children's primary caregivers to assess their exposure to violence at the age of 5, 7 and 10 years. They found that by the time children reached 10- year-old mark, 17 per cent of kids were victims of domestic violence in their own households, 24.2 per cent had been bullied on a regular basis, and 26.7 per cent had been physically or verbally abused by an adult. As a result of such abuse, at that point some children were already taken into protective custody.

Due to the fact that some children in the study experienced more than one type of abuse, the investigators divided them into three different groups. The first group included children who had experienced only one type of abuse (29 per cent); children in the second group experienced two or more types of violence (16.5 per cent); and the third group included kids who had never experienced any type of abuse (54.2 per cent).

After all the measurements and calculations, researchers came to the conclusion that telomere length shortened in all the kids as they grew older. However, the length eroded significantly faster in the 39 children who had experienced more than one type of child abuse. Shalev hazarded a rough estimate that these kids had lost perhaps between seven to ten years of their lives when compared to kids who had more peaceful lives. It was not possible for the team to find out if one particular form of abuse, such as bullying, for example, caused more damage than domestic violence. However, they did discover that going through more than one form of abuse had detrimental effects on the kids.

It is still unknown how, exactly, telomeres "wear and tear," though scientists suspect that inflammation markers triggered by stress can have negative effects on telomeres. They say that the research on the matter is very promising, including the discovery of an enzyme that can make telomeres longer. There is some evidence from animal studies that it is very possible to reverse the process of aging, Shalev said. There is also some evidence that the acceleration of telomere erosion can be slowed down, he added. So there is some hope for these children.

The study is published in the journal Molecular Psychiatry.