Friday, June 15, 2012

Violence may mar kids’ DNA with signs of aging

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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