Andrew Weil M.D. - Healthy Aging: A Lifelong Guide to Your Well-Being

In 2002, I turned sixty. To help celebrate the occasion, friends organized a surprise party for me. After the festivities, there came a time to reflect, and when I did I came to an uncomfortable conclusion: I am closer to a time when my energy and powers will diminish, when I will lose my independence. Sixty is about the time that organs of the body begin gradually to fail, when the first hints of age-related disease begin to appear.

I hardly notice my aging on a day-to-day basis. When I look in the mirror in the morning, my face and white beard seem the same as the day before. But in photographs of myself from the 1970 s, my beard is completely black. Looking at old photographs, I can't help but notice the physical change that has taken place in the course of thirty years. If I pay attention, I can notice other changes in my body: more aches and pains, less resilience in meeting the challenges of traveling, less vigor on occasion. And my memory may not be quite what it used to be. At the same time, despite the evidence, some part of me feels unchanged, in fact feels the same as when I was six. Almost everyone I talk to about aging reports similar experiences.

Some years ago I went to my twenty-fifth high school reunion, the only school reunion I have ever attended. I had not seen most of my classmates since our graduation in 1959. A few of them were just as I remembered them, hardly changed at all, closely matching the images in my memory from a quarter century earlier. Others looked so aged that I could barely find points of coincidence with the pictures of them I had in my head. Why the difference? Why are some individuals so outwardly altered by time and others not? Or, in other words, why is there often a discrepancy between chronological age and biological age? I believe that the answer has to do with complex interactions of genetics and environment. I also believe, based on evidence I have reviewed, that we have control over some of those factors.

I do not subscribe to the view that aging suddenly overtakes us at some point in life, whether at sixty or some other milestone. I meet researchers, physicians, and others who believe that we are born, grow rapidly to maturity, and then coast along on a more or less comfortable plateau until we begin to decline. They call the period of decline senescence and consider it distinct and apart from what came before. If one looks only at the physical aspects of life, especially on the cellular level, this is a plausible view.

Cells from old organisms are different from cells of young ones, and observations about how they differ are the basis of biogerontology, the new science of the biology of aging. It is biogerontologists who promote the idea that aging is a programmed phase of decline following the plateau of maturity. In their view senescence is a discrete phase of cellular life coincident with loss of the cells ability to divide. Senescent cells can still perform many of the functions of life, but they cannot reproduce. When researchers attempt to take cells from organisms, whether plants or animals, and grow them in test tubes, senescence soon overtakes the cultures, cells stop dividing, and the cultures die. (In human life, senescence equates with the period of functional decline that precedes death, with the appearance of age-related diseases.)

By contrast, when cells turn malignant, they often become immune to senescence. Cell biologists refer to this change as immortalization. It is one of the most curious and important characteristics of cancer, and I will describe it in more detail later. It points to an equally curious and important possibility about aging, namely, that the mechanics of aging in cells may have evolved as defenses against cancer. Malignant growth may be immortal at the cellular level, but it has the potential to disable and kill entire organisms prematurelythat is, before they can pass on their genes and contribute to the survival and evolution of the species. For life to continue, prevention of malignant growth must be a priority.

In any case, I find it more useful to think of aging as a continuous and necessary process of change that begins with conception. In the words of an Eastern philosopher:

The sun at noon is the sun declining;

The person born is the person dying.

Wherever you are on the continuum of aging, it is important to learn about how to live in appropriate ways in order to maximize health and happiness. That should be an essential goal for all of us. What is appropriate when you are in your twenties is likely not to be appropriate when you are in your fifties.