Scientists are pulling more data in to demonstrate apparent systematic differences in the biochemistry of aging between people of different socio-economic groupings.

People in lower social classes are biologically older than those in higher classes, according to research. A study of 1,552 volunteers revealed a low social status can accelerate the ageing process by about seven years.

The UK/US team analysed key pieces of DNA called telomeres which are thought to correlate to biological age.

...

researchers looked at 17 pairs of identical female twins, who had begun life in the same socio-economic class but were currently in different social groups.

They found on average, the telomeres of the twin in the higher social class were significantly longer than those in the lower social group - the difference equated to about nine biological years.

...

This obviously begs the question 'Why?'

"The theory we have come up with is that it is related to the stress of being in that social status compared to someone who is not in that social status.

"The strain of being in that job, the effort-reward imbalance, self esteem and just generally the psychological stress of having lots of areas you cannot control in your life are perhaps more important than we have realised."

He said this may have a biological impact on the body, making cells divide more quickly and reducing the telomere length.

The scientific term for those last points would be "outright guesses." Looked at more closely, this seems to be a case of knowing enough to aptly demonstrate that you don't really know enough. Socio-economic status is correlated with all sorts of line items - wealth, education, intelligence, and so forth - that are themselves strongly correlated with health and longevity. In many of these cases, it's far from clear that anyone has presented a convincing answer as to which side of the correlation is causative, and to what degree. It may be a feedback loop rather than straight causation, and most likely varies from case to case and time to time as well.

There is a large and persistent association between education and health. In this paper, we review what is known about this link. ... We suggest that increasing levels of education lead to different thinking and decision-making patterns. The monetary value of the return to education in terms of health is perhaps half of the return to education on earnings

The original form of the telomere theory of aging - that reductions in telomere length alone are the principle root cause - is pretty much abandoned at this time; some studies even suggest that telomere length and life expectancy are not coupled:

This longitudinal study of the elderly and oldest old does not support the hypothesis that telomere length is a predictor for remaining lifespan once age is controlled for.

Shorter telomeres are, however, associated with increased incidence of cancer, and a number of startup companies are working on therapies based on this relationship:

For a long time scientists believed [that] the length of our lives was meted out in our telomeres - the protective caps at the ends of the threadlike chromosomes that carry our genes. But life is never as simple as legend, and most researchers have abandoned the telomere theory of aging. They haven't given up on telomeres, though. Scientists are now testing whether degradation of these termini heralds the maladies associated with growing old, such as heart disease, dementia, and cancer. Understanding the association between telomeres and disease could lead to better treatments for cancer or new ways to stay healthy as we mature.

There an answer in there somewhere - but I think it's very bold and early to be jumping into this mess of correlations with any particular explanation. It would be good to run the whole study again with better biomarkers, say. Even better than that, recognize that time is far better spent acknowledging that we're all suffering from a condition that will deliver suffering, pain and death - and then doing something about it rather than simply observing it.

The Methuselah Mouse Prize is the premiere effort of The Methuselah Foundation; a scientific competition designed to draw attention to the ability of new technologies to slow and even reverse the damage of the aging process, preserving health and wisdom in a world that sorely needs it.

Technorati tags: aging, medical research

Posted by Reason at July 20, 2006 9:45 PM | TrackBack (0)