New research shows that growing up in a disadvantaged environment can lead to DNA damage in children as young as nine. This damage also occurs in the ageing process and is likely to be a result of chronic stress, showing how early interventions to reduce environmental disadvantage are crucial.
This is the first study that has investigated the relationship between genes and stressful environments using telomere length as a biomarker. Telomeres are protective caps on the end of DNA strands (like the plastic caps on the ends of shoelaces) that stop the DNA getting shorter as it replicates. Telomeres shorten with age, and abnormal telomere biology has been extensively linked to depression and several forms of cancer.
The study, published in the Proceedings of the National Academy of Sciences of the USA, measured the telomere length of 40 African American nine-year-old boys and found that those who grew up in tougher environments (determined by factors such as socioeconomic status, family stability and harsh parenting) had on average 20% shorter telomeres compared to those with advantaged upbringings. The genetic profile of the boys determined how serious the environmental effect was: those with certain gene variants related to serotonin and dopamine pathways (high ‘genetic sensitivity’) had even shorter telomeres if they grew up in stressful environments, compared to those with low genetic sensitivity growing up in a similar environment. Conversely, those with the highest genetic sensitivity scores had the longest telomeres of the boys growing up in advantaged environments. This shows how the effects of the environment on physiology are modulated by genes.
This telomere shortening suggests that chronic stress leads to a physiological process similar to ageing in these young children. As co-author of the study, Sara McLanahan said: “Our study… really highlights the importance of early intervention to moderate disparities in social and educational opportunities.”
The full paper can be found here: http://www.pnas.org/content/early/2014/04/02/1404293111.full.pdf