Friday, June 15, 2012
Children who have suffered violence might truly be older than their years. The DNA of many 10-year-olds who experienced violence shows wear and tear normally associated with aging, a study has found. The study examined telomeres, special DNA sequences found at the tips of chromosomes. Much like plastic shoelace tips, they prevent DNA from unraveling. They also shorten each time cells divide—thus limiting how many times a cell can reproduce and creating a loose association between telomere length and aging, biologists say. The new study found “telomeres can shorten at a faster rate even at a really young age, while kids are still experiencing stress,” said Idan Shalev, a post-doctoral researcher in psychology and neuroscience at Duke University in Durham, N.C. Shalev used data from an ongoing survey that has followed 1,100 British families with twins, now age 18, since the twins’ birth. Shalev and colleagues analyzed DNA samples taken when they were five and 10 years old. The researchers also learned, based on extensive interviews with the mothers, which children experienced violence in their younger years, including domestic violence, frequent bullying or physical maltreatment by an adult. Many, though not all, of he children with two or more kinds of past violent exposures had significantly more telomere loss than other children, according to the new study, published in the journal Molecular Psychiatry. Since shorter telomeres have been linked to poorer survival and chronic disease, this may not bode well for those kids, the researchers said. The findings suggest a mechanism linking cumulative childhood stress to telomere maintenance and accelerated aging, even at a young age, they added. “Research on human stress genomics keeps throwing up amazing new facts about how stress can influence the human genome and shape our lives,” said Duke neuroscientist Avshalom Caspi, a co-author of the research. Caspi co-led the survey that provided the data, called the Environmental-Risk Longitudinal Twin Study. “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,” said Duke neuroscientist Terrie Moffitt, who conducted the survey with Caspi. The researchers plan to further explore the issue by measuring the average length of telomeres in the twins now that they are adults, and to repeat the study in an older group of 1,000 people.