"Long before it's in the papers"
April 24, 2012

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Violence may mar kids’ DNA with signs of aging

April 24, 2012
Courtesy of Duke University
and World Science staff

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.

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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 existing study that has followed 1,100 British families with twins, now age 18, since the time those twins were born. 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 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.