Map of life expectancy at birth from Global Education Project.

Friday, July 25, 2008

Time and Tide

Colin Farrelly's comments on the previous post (and please read if you haven't already) require us to think about some of the most fundamental questions in public health and health care ethics.

First let me get some administrative business out of the way. One of the questions I raised was about priorities. I never said we should not invest in research into slowing the aging process, nor do I see any contradiction between doing such research and simultaneously tackling other urgent problems. After all, we're spending $10 billion a month in Iraq and squandering even larger sums on building stealth bombers and what not.

But that's the problem. I would expect that anti-aging research has a relatively politically powerful constituency, among affluent people in affluent countries. My voice will probably continue to cry in the wilderness about other issues.

A couple of other quick points. Some of my physician friends are less optimistic than Dr. Farrelly about the prospects for effective anti-aging therapy any time soon. I have no expertise to judge that question. I will note that recently, we have made substantial progress in understanding the biology of what I might call endogenous (as opposed to infectious) disease processes, such as cancer, auto-immune disorders, and obesity. However, we have so far found progress translating this understanding into effective therapeutics to be disappointing. The processes turn out to have layers of complexity that makes intervention difficult and often counterproductive. Ironically, for example, while cancer is associated with aging, anti-aging therapies might perversely greatly increase the risk of cancer. So it remains to be seen how soon these speculations will confront reality. That's not an argument against continuing research, obviously, just an observation.

Now for the deep stuff. There are two possible scenarios for an anti-aging intervention, as Dr. Farrelly suggests. One is that it compresses the morbidity associated with aging -- that it means we go along through our 70s and perhaps beyond without the woes that have afflicted the aged since our ancestors crawled out of the ocean. (I'm assuming that fish experience aging differently than do tetrapods. I had to ground the figure somewhere in time.) Then we suddenly fall apart like the Wonderful One-hoss Shay, and go peacefully. It's hard to argue with that.

Possibility two is that it just pushes the whole thing back a few years. When you're 70, you have the physiology of a typical 63-year-old. At 80, you're like a 73-year-old, and so on. Now this is a different matter altogether. We get some more good years out of the deal, but then all is as before. Here we must reflect on the lifespan as a fundamental fact. Should the goal of medicine be to extend it? Most of us want more life, of course, as a selfish proposition, but there are tradeoffs for society.

Assuming that the earth has a carrying capacity, that resources are limited and that there are costs to a larger human population, if we live longer, we're taking something from our children. In addition to consuming resources, we're standing in their way. If we keep working through our seventies and beyond, we're clogging up the pipeline for the most desirable jobs, for leadership roles, for status. Human society is designed around the fact of aging and death. If we radically change the relevant parameters, we change society. Of course those young people will eventually get around to that promotion, or academic appointment, but without the energy and idealism of youth. The time of family formation and child rearing will be one of lesser affluence and less satisfying and enriching employment.

How would all this affect the culture, the general mood? Politics? And even the health of the young?

I am not one to invoke mystical ideas about "nature." Unlike some who would attack the idea of conquering age from positions that are equally likely to be labeled right or left, I believe that human nature is what we make of it, not some sacred and immutable quality. If we can be smarter, healthier, happier, let's go for it. But there is the law of unintended consequences. Fool around with one thing, and something else will bit you on the ass. So I'm just saying, let's think this thing through. And don't forget -- there's no telling what numbers we're talking about here. If we could delay aging by 7 years, why couldn't we delay it by 20? Or more? What then?

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