Tuesday, September 18, 2012

Aging Research in Canada (Some Reflections)

Yesterday I attended this interesting talk on the 5 year priorities and vision of Canada's Institute of Aging.

Many interesting issues arose in the talk and the discussion that followed that illustrate the ongoing challenges which the field of biogerontology faces. I thought I would offer some thoughts here on my blog about the issues that struck me as important ones that need to be addressed if research on aging is to become a true societal priority (as I believe it should be).

I will limit my comments to three issues:
(1) projections of rises in life expectancy
(2) concerns of generational fairness (e.g. why spend money on aging when we could use those funds to help kids)
(3) the role of socio-economic factors in health in late life.

(1) Life Expectancy: Can We Estimate the Future Based on the Past? NO

At one stage during the talk a statistic was mentioned that 50% of the children born today in Quebec will live to 100 years of age. What are we to make of such a claim? The best response is the one made by biodemographers who point out that biology constrains math. While we can create mathematical projections of how long people will live in the future, based on past increases in rises in life expectancy, this is flawed because it does not consider the biological limitations of the human species. Gaining extra healthy years is easier to do when life expectancy is low than it is when life expectancy is high. Here is an example that is often used to explain this-- suppose that the world record for the 100 meter sprint is 0.5 seconds faster today than it was 10 years ago (from 10.0 seconds to 9.5 seconds). From this, we could make a mathematical projection that 100 years from now, the world record for the 100 meter sprint will 4.5 seconds. That is of course ridiculous. New training techniques and equipment might help a sprinter shave off 0.5 seconds when the record is above 10.0+ seconds, but it does not follow that we will continue to shave off 0.5 seconds every 10 years. Humans can only run so fast. Take this same logic even further. In 200 years, the world's fastest sprinter should be able to run 100 meters in -0.5 seconds!!! This is faulty reasoning when applied to sprinting, and it is faculty reasoning when applied to predicting rises in human life expectancy.

For a population to approach a life expectancy near 100 years we would have to eliminate most cancers, heart disease and stroke. Considering we have not yet eliminated any one of these diseases, the suggestion that we will continue to increase life expectancy at the same rate as we have in the past is simply unfounded. Take mice in the laboratory. On average, they could life about 2 years if they are fed, protected from predators, etc. Can we get them to live significantly longer by trying to treat all the diseases that afflict them in late life? No. They can live significantly longer (and healthier) lives by eating a calorie restricted diet, by activating longevity genes, etc. The message to take from this-- we will only "add life to years (rather than years to life)" if we tackle aging itself. Centenarians (those that live to 100+ years) are an exceptional case. And genes are a major determinant of exceptional longevity. We should invest more research dollars into the biology of aging than we do into any one specific disease of aging (e.g. cancer, heart disease, etc.). Unfortunately my sense is that we don't come even close to this. Biogerontology continues to be disadvantaged as a field of scientific inquiry given the domination of the conceptual assumptions of "negative biology".

2. Generational Fairness: How much to Spend on the Young Vs Old?

During the discussion period someone raised that point that some might argue we should divert the funding on aging to helping the young. I have a few responses to this. Firstly, it is interesting that this point arises when the topic is research on aging but not research on disease. The vast majority of research dollars are spent on disease research, and these diseases primarily afflict the elderly. But biogerontology is typically singled out for the generational fairness objection. So my quick response is this-- we would save money by tackling aging itself (rather than every disease of aging) and could invest those savings into research that aids the young. But my more expansive answer is to point out that the generational fairness issue is predicated on some flawed assumptions. Namely, that research on aging won't benefit the young. Most children in Canada will suffer chronic disease, it is just a matter of time. When they become seniors they too will suffer from AD, hearing impairment, arthritis, cancer, stroke, diabetes, heart disease, etc. So an investment into the biology of aging IS an investment into the health of those young today. It could benefit them when they will need it the most (i.e. when their bodies and minds become highly vulnerable to disease in late life).

3. Socio-economic Inequalities and Life Expectancy

During the discussion period someone raised the point that we ought to be addressing socio-economic disparities rather than studying aging itself. Their point was that differences in life expectancy stemmed from differences in education and wealth rather than any biological differences between people. My response: that is partly true, and partly false. Yes socio-economic factors (especially education) are important. They explain the differences in life expectancy between "average people" (by which I mean those individuals that not possess the genes associated with a short or exceptionally long life).

Here is a recent study that examines the impact race and education have on differences in life expectancy in the United States. There is a difference of 14.2 years for White men who have 16+ years of education and Black men with less than 12 years of education. This is a significant problem that should be addressed. However, there is an even larger health disparity that people often ignore. The greatest health disparity between people does not track race, education or wealth (hence why it is largely off the radar). What it tracks is genetic inheritance . Those born with the "golden genes" associated with the exceptional longevity of centenarians and supercentarians (110+) enjoy decades more health and life than the average person. And the longest lived are not elite athletes, nor are they are graduates from IVY league schools, nor are they from extremely wealthy families (though they are more likely to be female than male). The biology of these individuals is different than that of most people in terms of the trade-off made between longevity and reproduction. This results in them living longer, healthier lives, at a cost of delaying and reducing their reproductive ability. This cost to reproduction is not so severe that it means one cannot have children. Most adults in this country delay and reduce their reproductive abilities already by using contraception. So the biological cost of exceptional longevity needs to be placed within its proper context. The value natural selection places on reproductive fitness ought not to be equated with the value we actually place on it.

This concludes the points I wanted to make. My sense of things, from hearing about the vision of the Institute and the new priorities it has identified, is that the Institute of Aging in Canada still struggles to get the respect, funding and support it deserves. This is no doubt due to many factors, such as the dominance of disease research, misconceptions about the true causes of health disparities, misguided sensibilities of fairness, ageist attitudes, and a general ignorance of the biology of aging and evolutionary biology in general. This makes selling the science to politicians and the general public a really tough sell. But I believe it is something that must be done if we hope to add healthy years to late life. So we must soldier on....