And, of course, there are other priorities, such as infectious diseases, pandemic preparedness, global health, and childhood disease prevention. If you asked Bill Gates, he would have completely different priorities. It could also be argued that these actually improve life expectancy much more than anti-aging studies by reducing things like infant mortality and infectious diseases.
Well, much of the historic increase in life expectancy is due to improvements in nutrition, sanitation, newborn care, vaccines, and more. Today, we don’t think of treating cancer or heart disease as a way to extend life expectancy, but in a fundamental sense, isn’t that exactly what it is?
The idea of an aging society is as follows. All of the non-communicable chronic diseases we currently suffer from, such as heart disease, cancer, dementia, and diabetes, are taken into account. All of these diseases are highly correlated with age. Age is the largest single risk factor for these diseases.
So their view is that we can deal with these diseases one at a time. Or you could say that because the root cause is aging, we should approach aging holistically, which has multiple effects.
That’s the theory. In fact, if you want a therapeutic intervention approved, you have to have the disease. The US Food and Drug Administration doesn’t call aging a disease, and the World Health Organization doesn’t call aging a disease, so what are we going to do in clinical trials? So clinical trials are usually about some aspect of aging, such as osteoarthritis or dementia.
Your book starts with something really small, down to the molecular level, and then builds a whole theory of aging from there.
I believe that aging is the accumulation of chemical damage to the body. That must necessarily mean that damage occurs first, starting with the genome, then the proteins that genes specify and make, and then the organelles and the cell’s ability to eliminate defective products. That’s a big factor.
And the effect that that has on the cells themselves is that when they sense a certain amount of damage, they enter a state called senescence. As we age, the accumulation of too many senescent cells can lead to serious problems such as inflammation and tissue damage. And when the stem cells responsible for tissue regeneration age or die, they become depleted, creating problems with tissue regeneration and even just maintaining the organism.
We need to look at this as different levels of complexity, each with its own characteristics of aging. In other words, it is a phenomenon that occurs with aging, and itself accelerates further aging.
There is also a metaphor that living organisms, that is, our bodies, are cities and societies. Individual factors aren’t enough to stop things from escalating, but they can start a cascade of things going awry.
Cells in our bodies are constantly dying and being replaced. Even though millions of cells are dying all the time, we don’t notice it and certainly don’t think of it as death. So what does death mean?