Jyoti Madhusoodanan in Nature:
Growing up in a stressful social environment leaves lasting marks on young chromosomes, a study of African American boys has revealed. Telomeres, repetitive DNA sequences that protect the ends of chromosomes from fraying over time, are shorter in children from poor and unstable homes than in children from more nurturing families. When researchers examined the DNA of 40 boys from major US cities at age 9, they found that the telomeres of children from harsh home environments were 19% shorter than those of children from advantaged backgrounds. The length of telomeres is often considered to be a biomarker of chronic stress. The study, published today in the Proceedings of the National Academy of Sciences1, brings researchers closer to understanding how social conditions in childhood can influence long-term health, says Elissa Epel, a health psychologist at the University of California, San Francisco, who was not involved in the research.
Participants’ DNA samples and socio-economic data were collected as part of the Fragile Families and Child Wellbeing Study, an effort funded by the US National Institutes of Health to track nearly 5,000 children, the majority of whom were born to unmarried parents in large US cities in 1998–2000. Children's environments were rated on the basis of their mother's level of education; the ratio of a family’s income to needs; harsh parenting; and whether family structure was stable, says lead author Daniel Notterman, a molecular biologist at Pennsylvania State University in Hershey. The telomeres of boys whose mothers had a high-school diploma were 32% longer compared with those of boys whose mothers had not finished high school. Children who came from stable families had telomeres that were 40% longer than those of children who had experienced many changes in family structure, such as a parent with multiple partners.