Monday, March 02, 2009

Aging Research and Making the Future Vivid

This post is also posted on the Women's Bioethics Project here.

In this post I try to make the case for getting those interested in bioethics and issues pertaining to women to join the cause of supporting the basic science that could lead to a deceleration of human aging.

At first blush the proposition that those interested in the health and welfare of women should support aging research might sound counterintuitive. When we hear the phrase "aging research" we might automatically envision the kinds of products we currently see advertised on TV, like "anti-aging" creams that promise to restore the youthful appearance of skin, hide wrinkles, etc. Such products reinforce demeaning ideals of "womanhood"-- that a woman's self-worth can be reduced to her physical appearance and thus every woman should do everything she can to present herself as "youthful" and conceal the signs of aging. Those are not the interventions, and that is not the message, I am talking about. Far from it.

By "aging research" I mean the scientific field of biogerontology which studies the biological processes of aging. And by an "anti-aging" intervention (which is currently hypothetical... there is nothing you can currently buy that decelerates aging) I mean a pharmaceutical that decelerates the rate of molecular and cellular damage caused by aging. An intervention could do this be mimicking the effects of calorie restriction (without actually requiring a restriction of calories). A deceleration of the aging process would delay many of the common diseases and conditions associated with aging (like heart disease, cancer, stroke, AD, etc.) and possibly compress morbidity and mortality. Thus people would enjoy more years of disease-free life than that possible given the current rate of aging for most humans.

When I talk to people about my interests in this area there are a number of reservations and concerns they have. Let me briefly identify, and address, two of them: (1) many feel that talk of retarding human aging sounds like mere science fiction; and (2) many express the viewpoint that it is distasteful to worry about decelerating aging when there is so much poverty and disease in the world. I will very quickly address (1) and then focus on (2), with particular reference to the situation of women.

Talk of retarding human aging will strike many as either pure science fiction, or, at best, the prospect of an "anti-aging" pill is a long, long ways off. This is a common reaction and one that would have been more reasonable to hold 20 or even just 10 years ago. But over the past decade amazing progress has been made in the field of longevity science which makes the prospect of a genuine anti-aging pill becoming available in the next 5-10 years a real possibility. In fact there are a number of human clinical trials currently underway involving resveratrol (an anti-aging molecule present in red wine) and Sirtris has trials for more concentrated compounds.

So the first hurdle for these products is to establish if they are safe and effective treatments for the diseases of aging. If so, they could be pursued as a preventative intervention to protect people (including all future generations) from the diseases of aging. By decelerating the rate of aging during adulthood we could reduce our risk of disease and death in late life, thus extending the number of healthy years humans could expect to live.

OK, so back to my main goal of encouraging those interested in the issues facing women to champion this area of scientific research. This brings me to concern (2). One might wonder why, given all the pressing issues facing women in the world today, that they ought to add aging and longevity science to the list of things to address. "Is it really a priority?" one might ask. "Is it a priority in a world with disease and poverty?"

This is a fair question. And the answer is "YES!". Why? Because most disease in the world today is caused by aging. Now you won't find data from the World Health Organization that states that explicitly. But what you will find are the data concerning the proximate (rather that evolutionary) causes of morbidity and mortality. But behind the proximate causes of most human deaths (like cancer and heart disease) are the biological processes of aging. In other words, it is not a coincidence that most people who suffer disease and death today are over age 60. The vulnerabilities of late life reflect the tradeoff that natural selection has made between the fitness of a parent and reproduction. Natural selection favors a strategy in which organisms invest fewer resources in the maintenance of somatic cells and tissues that are necessary for indefinite survival of the individual (source).

The enormous and unprecedented disease burden the world will experience this century makes vivid the human toll of this tradeoff. Take the year 2005, the latest year that one can easily find the stats from the World Health Organization. Approximately 55 million people died in 2005. Of that number, 35 million died of chronic disease. That number is twice the number of deaths due to infectious diseases (including HIV/AIDS, tuberculosis and malaria), maternal and perinatal conditions, and nutritional deficiencies. That is a staggering figure. Furthermore, between the years 2005-2015 WHO estimates that 220 million people will die from chronic disease, most of them (144 million deaths) in lower middle income countries like China and India. The diseases associated with aging are not, contrary to popular perception, only a problem for people living in the developed world. Indeed, being vulnerable to disability and frailty is a much greater disadvantage if one lives in a poor society with no decent health care or pension, as the link between income and "ability to work" is much more direct. So the chronic diseases associated with aging are a problem for all societies, not only the richest countries in the world.

I don't want to fixate too much on the global figures for chronic disease but some brief comparisons with other events in human history will help us get a sense of the magnitude of the problem of chronic disease. It is estimated that between the mid-14th and mid-17th centuries, the "Black Death" plague killed approximately 25 million people. This means that the current deaths caused by chronic disease in just one year is equal to the number of total deaths caused by three centuries of the "Black Death" plague! The 220 million deaths caused today by a decade of chronic disease is closer to the scale of death from a few decades of small pox. In the twentieth century small pox is estimated to have killed between 300 and 500 million people. By 1980 small pox had been eradicated thanks to the small pox vaccine.

Could we vanquish chronic diseases like heart disease and cancer this century, like we did small pox last century? To make serious headway against chronic disease we must understand the ultimate (that is evolutionary) and not just proximate cause of disease. There is no virus that is responsible for all cancers, heart disease, stroke, AD, etc. But if we better understand the biological processes of aging we may be able to modify the rate of aging so that we reduce our risk of disease and death in later life. So tackling aging is an issue of preventative medicine. An anti-aging pill that slowed down the molecular and cellular damage of aging would extend the period of healthy life humans could expect to live.

In order to appreciate the great benefits this could confer upon women, especially women in poorer countries, consider the facts of this report:

Women comprise the majority of the older population in virtually all countries, largely because globally women live longer than men. By 2025, both the proportion and number of older women are expected to soar from 107 to 373 million in Asia, and from 13 to 46 million in Africa.

And.....Osteoporosis and associated fractures are a major cause of illness, disability and death, and are a huge medical expense. It is estimated that the annual number of hip fractures worldwide will rise from 1.7 million in 1990 to around 6.3 million by 2050. Women suffer 80% of hip fractures; their lifetime risk for osteoporotic fractures is at least 30%, and probably closer to 40%. In contrast, the risk is only 13% for men.

To fully appreciate the benefits of an intervention that decelerates human aging we must make the future health prospects for women in the world today more vivid. In particular we need to consider what the situation of those vulnerable today will be in the decades to come-- like the 373 million older women who will be living in Asia by 2025. These women will be vulnerable to the chronic diseases and disabilities of aging. But we could reduce these risks if we could decelerate human aging.

One of my favourite Ted Talks lectures is this one by Harvard psychologist Dan Gilbert. It is a brilliant presentation, outlining how our decisions are skewed by a variety of limitations and biases.

At the end there is an apt question from biogerontologist Aubrey De Grey concerning how these cognitive limitations impact our ability to see aging for the threat that it actually is. Gilbert responds by noting that humans can imagine the near future much more vividly than the far future. That is why we are more likely to address the problems of today rather than those of tomorrow. And this is a real problem for humanity given that the health problems facing 2 billion persons over age 60 by 2050 will be enormous.

To get people to make more sage decisions about the far future we need to provide them with details. We need to help them become psychologically connected with the future. The more detail people have about the far future the more likely they will make decisions about it like they do the near future (though we don't always do the latter well either, but that is the subject for another post! :)).

So my plea for getting those interested in women's health and welfare to get behind aging research is one that seeks to make vivid the threat that senescence poses to the health prospects of women this century. Senescence will likely cause more disease and disability for women this century than any other cause. Senescence not only threatens our health and survival by increasing the risk of fatal diseases (like heart disease and cancer), but also one's ability to contribute to their communities and families. Aging research is thus a vital component of developmental economics. The sooner we increase public support and funding for this science, the sooner we will be able to reduce the risk of morbidity and mortality for the world's aging female populations.