Perceived age as a bio-marker of ageing

Do you look younger than your age? If so you have reasons to cheer! According to a new study as per Kaare et al, the perceived age is directly related to the actual ageing and inversely related to your telomere length.

It is well established that telomere length is a good indicator of ageing and also plays a crucial role in diseases like cancer, and when it becomes too small hastens cell apostasies.   in this study, what Kaare et al found that of the twins, the one who had more perceived age also had a shorter telomere length on average and thus was more aged.

They also found a long -term effect of perceived age on mortality and thus more corroborating proof about this association. They used a cohort study of twins to reach their conclusions. I’ll quote from their abstract and discussion:

Results: For all three groups of assessors, perceived age was significantly associated with survival, even after adjustment for chronological age, sex, and rearing environment. Perceived age was still significantly associated with survival after further adjustment for physical and cognitive functioning. The likelihood that the older looking twin of the pair died first increased with increasing discordance in perceived age within the twin pair—that is, the bigger the difference in perceived age within the pair, the more likely that the older looking twin died first. Twin analyses suggested that common genetic factors influence both perceived age and survival. Perceived age, controlled for chronological age and sex, also correlated significantly with physical and cognitive functioning as well as with leucocyte telomere length.

Conclusion: Perceived age—which is widely used by clinicians as a general indication of a patient’s health—is a robust biomarker of ageing that predicts survival among those aged 70 and correlates with important functional and molecular ageing phenotypes.

Perceived age predicts survival among people aged 70, even after adjustment for chronological age, sex, and other readily measurable biomarkers of ageing. Perceived age also correlates with age related phenotypes such as physical and cognitive functioning and leucocyte telomere length. Clinicians use perceived age as part of their assessment of patients, but research on the validity of the approach has been sparse.1 13 14 We have shown that perceived age based on facial photographs is a robust biomarker of ageing that does not depend on the sex, age, and professional background of the assessors.
In our analysis, the comparison within pairs of dizygotic twins controlled for rearing environment and, on average, half the genetic factor variants present in a population, while the comparison within pairs of monozygotic twins controlled for all genetic factors and rearing environment. We found indication of common genetic factors influencing both perceived age and survival because controlling for genetic factors (the comparison within monozygotic pairs) removed the association between perceived age and survival (fig 3). This was in contrast with the results for the overall twin sample and for the dizygotic twins, where comparison within pairs showed a clear “dose response” association between perceived age and survival (fig 2). Hence, the comparison within pairs suggests that there are genetic factors influencing both survival and perceived age (for example, genetic factors that influence the condition of cardiovascular tissue could affect the risk of myocardial infarction as well as the appearance of skin). Full details of this study design can be found elsewhere.

it is important to note that they found the association only in dizygotic twins and not in monozygotic twins, so apparently genetic factors determine both perceived age and actual mortality/ageing. If the effect had been also found in monozygotic twins perhaps epigenetic /non-shared environmental factors would be the deciding factor, but in their absence it is wise to conclude that genes are the third factor that has led to perceived age and ageing correlation and neither is causative of the other. Alternately , underlying tissue ageing might directly affect perceived age and might be evolutionary coded for m, especially in females, so that males could determine the youth and fecundity accurately. In that way the direction would be causal but in the other direction.

What it means is that if you have young looks as per your age, there is reason to rejoice; if not you can not do much by looking young even if you indulge all your money in face lifts etc. Of course there are other benefits of looking young artificially, but increased actual age might not be one of them.

Christensen, K., Thinggaard, M., McGue, M., Rexbye, H., Hjelmborg, J., Aviv, A., Gunn, D., van der Ouderaa, F., & Vaupel, J. (2009). Perceived age as clinically useful biomarker of ageing: cohort study BMJ, 339 (dec11 2) DOI: 10.1136/bmj.b5262

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