Mixed evidence for biological ageing being socially patterned
posted on: Jul 25, 2012
Research is increasingly interested in the specific biological processes that link people's social circumstances and their health. One of the ways in which socioeconomic circumstances may affect the body is through accelerating biological ageing, the rate at which our cells and organs deteriorate and our bodies lose function. One proposed way of measuring biological ageing is by using a biomarker called telomere length. Telomeres are structures present at the end of our chromosomes (structures that store our DNA in a cell) that help to protect against irreversible genetic damage. As we age, our telomeres get progressively shorter, although the rate of this shortening is not identical for people of the same chronological age. This effectively makes telomere length a type of ‘biological clock’.
A new study by Tony Robertson and colleagues from the Unit, University College London and Glasgow University has investigated if socioeconomic circumstances are associated with telomere length in participants from the West of Scotland Twenty-07 Study. This research found that poorer socioeconomic circumstances, particularly in childhood, were associated with shorter telomeres in those aged 35 years, but not for those aged 55 or 75. This is counter to what one would expect, i.e. that differences in telomere length would widen with age.
Among the 35-year-olds, for example, those in the most deprived socioeconomic groups at age 15 (based on their parents’ job types) were roughly 20 years biologically older than those from the least deprived groups at age 35. This may suggest that childhood could be an important period in our lives for socioeconomic circumstances to accelerate biological ageing and affect health later in life.
There are a number of possible explanations for why these social differences in telomere length were not apparent in the older cohorts. It may be that at older ages telomere shortening is driven more by illness and disease than by social circumstances. Alternatively it may be that the most socially deprived participants in the study have died before the blood samples were taken at ages 55 and 75, thereby removing those with the shortest telomeres from the study. Another possible explanation is that telomere length becomes a less reliable marker of ageing in older adults. Further research is needed to improve our understanding of the reasons for these differences by age groups.
More information can be found here