Monday, April 07, 2008

Aging Research and Aggregation

This post is, in many respects, the latest update to my series of “Genetic Justice” posts (so this would be update #3, here are #1 and #2)

As I’ve noted many times before (e.g. here and here), a great deal of my current research concerns the moral imperative to retard human aging. This aspect of my research sprung out of my ongoing work on genetic justice, a topic I have been working on for about the past 8 years now.

In fact, digging up some old blog posts, I can actually track down the *precise moment* when I started thinking more seriously about aging research. It started at this event at Stanford. In particular, I was really impressed by Aubrey De Grey’s JME paper on “Life extension, Human Rights, and the Rational Refinement of Repugnance”. And so it was Aubrey’s presentation that got me first thinking seriously about these issues.

I was so impressed by Aubrey that I knew I just had to include him in the event I organized last summer at Oxford on “Genetic Justice”.

Indeed, at that conference it was interesting to hear some arguing that we need to do more to tackle cystic fibrosis and then others arguing for tackling aging. Of course we ought to tackle both, but how do we go about determining priorities in such a scenario? The imperative to tackle any one disease is complicated by many factors. Those born with CF can only expect to live to their 30’s. When compared to individuals with CF, those that suffer age-related afflictions are fortunate. However, age-related afflictions are much more *prevalent* in the population. And so how do we compare the imperative to treat a rare, early onset condition with the duty to treat cancer or retard human aging? I think such questions are very important, and yet extremely complex and difficult to answer.

When I tell people I am working on justice and aging research they are often very puzzled. And here is how I would summarize the common response: “Justice may impose many different obligations on us— like eliminating world poverty, combating climate change, respect for cultural equality, eliminating gender inequality, etc. etc..- but how on earth can you say that justice requires us to modify the biological processes of aging so that we retard human aging?

This question is a very valid question. Indeed, it is something that has preoccupied most of my thoughts for the past two years! And over the past few days an important piece of this puzzle fell into place for me. So I wanted to post this blog to capture my initial thoughts about this “eureka moment!” in my thinking about these issues.

As I was revising one of my latest papers on justice and aging research (which builds on this previous post), I came across an excellent and very helpful discussion on Aggregation in chapter 5 of Scanlon’s excellent book What We Owe To Each Other.

In this chapter Scanlon explores how the contractualist could incorporate some room for aggregation without leading to the counterintuitive consequences of utilitarianism. These counterintuitive scenarios are typically ones where we have the option of preventing a large number of people from suffering a very minor harm (e.g. like a headache) or help a smaller number of people who will suffer a serious harm (e.g. premature death). In such cases a standard cost-benefit analysis would prescribe we should help the larger numbers because, once we add up the large amount of small benefits, they *outweigh* the large benefits that would only be conferred upon a small number of people.

But the important part of Scanlon’s chapter that I am particularly interested in is his acknowledgement that much hinges on the broad categories of moral seriousness. Let me explain how I think this can be very helpful to those championing aging research.

To suffer disease and disability is to suffer disadvantage that rates on the broad category of “moral seriousness”. Of course some diseases and disabilities are more serious than others. And the *Priority View* would prescribe that, all-else-being-equal, more weight should be placed on benefits to those who suffer the worst forms of disadvantage.

So let’s illustrate this with an easy two person example. Suppose there are two individuals in need of life-saving medical intervention. Person A suffers from an early onset disease (let’s say CF) and will die by age 35 if we do not help them. Person B suffers from a late onset condition (let’s say cancer) and will die at age 70 if we do not help them. We can only afford to help one of these two patients. What are we to do?

If one takes the Priority View to entail (as I think it does) that we look a person’s *expected life-time acquisition* of the natural primary goods (like health), then it clearly is the case that person A is in need of more urgent aid. Without intervention A will only live half the number of years of B. And so if we had to decide between A and B we should go with aiding A. Person B cannot reasonably reject a principle that gives greater moral weight to the interests of a person who is much worse off in terms of their expected life-time acquisition of health.

Now in this first case the problem of aggregation does not arise because there are only 2 people. So let’s add in some further facts to the example to see how the numbers complicate things. We now have 2 categories of individuals- those with an early onset disease and those with a late onset disease. Those in the first group (A) can expect to live to 35 (without treatment); those in the second category (B) will die at 70. The number of people in the two groups is very unequal. There are only 4 people in A and 10 000 in B. We can only provide treatment to one group, which group should we aid?

In this case the numbers are stacked in favour of aiding B rather than A. However, this conclusion is not arrived at by a simple aggregation of benefits across lives. For the contractualist, aggregation *within* each person’s life can justify why helping B rather than A is justified. Aiding A would mean that all 10 000 people in B would suffer premature death by disease. While dying of disease at age 70 might not be as serious as dying of disease at age 35, it is “morally relevant” in this case. And so the Complaint Model (which insists that the justifiability of a moral principle depends only on various individuals’ reasons for objecting to that principle and alternatives) could be satisfied in this instance. The four individuals in A, if they protest, could only respond in the following fashion: “The principle that prescribes aiding B (rather than A) will result in our premature death. Granted aiding us rather than B would also result in premature death for the people in B, but at least they have enjoyed a longer life than we have had the opportunity to enjoy”.

But when the numbers in this case are so unequal, so that for every life we could save/extend in A we could save/extend 2500 lives in B, and the benefits at stake are “morally relevant” (even though not equal), the decision to aid B is justified. And this in fact justifies why funding for cancer research dwarfs funding for rare (yet early onset) diseases. (Though this is not to say that the current levels of funding for medical research in general are fair and reasonable, I will leave that issue open for now)

So this then sets the stage for talking about aging research. Now consider the following two examples. People in Group A will die from cancer. People in Group B will die from the diseases of aging. This latter category includes most people in Group A, *plus* most people who die from heart disease, AD, diabetes, stroke, infection, bone fracture, etc., etc.

And thus once one clarifies what retarding human aging would actually mean to an individual’s life, we see how it passes Scanlon’s test for being “morally relevant”. As the author’s of the excellent paper “In Pursuit of the Longevity Dividend” argue, slowing aging by just 7 years would reduce, by approximately half at every age, our risk of death, frailty and disability. So retarding aging is not about prolonging the number of years we spend in the latest stages of the human lifespan; it is about increasing the number of *disease-free years* individuals can expect to enjoy. And once we realize this, we see that the current neglect of aging research is unjustified. For the goal of extending the number of disease-free years is what justifies our funding of medical research into cancer, heart disease, diabetes, etc. But the strategy of tackling one disease at a time is an inefficient and narrow approach to health extension. We should also explore the prospects of intervening in the biological processes of aging itself. This could confer significant health benefits on individuals (and enormous socio-economic benefits on society as a whole).

And so if I go back to the central principle of genetic justice I have defended elsewhere (the lax GDP) I think modifying our biology to retard human aging can be justified to the least advantaged (even though we have not yet developed therapeutic interventions for all early onset diseases). While these scientific advances would exacerbate genetic inequality between the "worst off" and those better off, they would create greater equality between the second least advantaged and the better off. And this is very important (even though it might exacerbate some level of inequality) as it would reduce the most prevalent diseases that afflict people in society.

Furthermore, aging research could actually help research into more rare conditions, for our understanding of the biology of aging is bound to confer some benefits to our understanding of early onset disorders (like pregoria).

And finally, I am not suggesting that funds be diverted from medical research into cures for rare early onset conditions into tackling aging. Rather I am suggesting that a greater portion of the funding we currently invest into tackling each age-related disease could be better spent on aging itself. And while we’re at it, we should also consider how much we invest in health related research in the first place, for we may be neglecting the interests of those who suffer both early onset and late onset disease.