IMAGE: WIKIMEDIA COMMONSAdversity early in life takes its toll on one's chromosomes: A study of 100 Romanian children found that the more time children spend in institutional orphanages before the age of 5, the shorter their telomeres.
While previous studies have found that telomere length in adulthood correlated with self-reported childhood stress, the new research, published today (May 17) in Molecular Psychiatry, is the first to quantify the immediate impact of early life hardship on telomere length.
"This is an exciting study with sound methodology that adds to the very recent body of work demonstrating effects of childhood adversity on telomere shortening," Audrey Tyrka, who was not involved with the study and studies human behavior and psychiatry at Brown University, said in an email to The Scientist. "[It] is of great interest because it focuses on institutionalized children who...
Telomeres are stretches of non-coding DNA at the ends of chromosomes that shorten with each cell division. In adults, shorter telomeres have previously been associated with aging, cardiovascular disease and cognitive decline, as well as oxidative and psychological stress. Recent research has suggested that adults with adverse experiences as kids tended to have shorter telomeres than controls [1. A. Tyrka et al., "Childhood maltreatment and telomere shortening: preliminary support for an effect on early stress on cellular aging," Biological Psychiatry 67: 531?4, 2009],[2. L. Kananen et al., "Childhood adversities are associated with shorter telomere length at adult age both in individuals with an anxiety disorder and controls," PLoS ONE 5: e10826, 2010.], but to date, no studies have looked at the more immediate impacts of childhood deprivation. "We assumed that early and/or chronic adversity would have a deleterious effect on telomere length," wrote pediatrician and neuroscientist Charles Nelson of the Children's Hospital Boston in an email.
Nelson and his colleagues randomly assigned children 6-30 months of age living in institutions in Bucharest, Romania, into two groups: Half were placed into foster care, and the other half remained in institutions, where they tend to receive less attention and live a more regimented lifestyle. The researchers then measured the length of the kids' telomeres when they were between 6 and 10 years old using a cheek swab. They found that the institutional group had significantly shorter telomeres than those children that had been taken into foster care, and that in both groups, telomere length correlated with total time spent in institutional care before the age of 54 months. "[The results were] completely consistent with our hypotheses," wrote Nelson, who is part of the Bucharest Early Intervention Project, which aims to study the neurological and psychological effects of institutionalization on children.
How exactly early life adversity would affect telomere length is unknown, but the brain undergoes many changes in early childhood [3. T.J. Silk and A.G. Wood, "Lessons About Neurodevelopment From Anatomical Magnetic Resonance Imaging," Journal of Developmental and Behavioral Pediatrics 32: 158-68, 2011.], such as the development of epigenetic patterns that affect gene regulation later on[4. T.L. Roth and J.D. Sweatt, " Epigenetic mechanisms and environmental shaping of the brain during sensitive periods of development," Journal of Child Psychology and Psychiatry 52: 398-408, 2011.] -- including genes that control telomere length. The authors speculate that, if early life stress derails these epigenetic patterns, there could be lifelong consequences.
While the study size was larger than those done previously -- , with 48 institutionalized children and 52 in foster care -- it is "smaller than you would like," Timothy Spector of King's College London's Twin Research & Genetic Epidemiology department who was not involved with the study, said in an email. "Nevertheless this study is further evidence pointing towards the potential long-term harmful effects of stress at crucial stages of life that could have consequences in adulthood."
S.S. Drury et al., "Telomere length and early severe social deprivation: linking early adversity and cellular aging," Molecular Psychiatry, doi: 10.1038/mp.2011.53, 2011.