Thursday, December 10, 2009

Global Aging: The *Real* Challenge of Our Times

Global aging is real, it's man made, and it threatens the health and economic prospects of the global population, especially the developing world.

Not only is global aging real, it's here now, and its effects are giving rise to a frighteningly new global phenomenon: a pandemic of chronic disease.

(1) Global aging is real.

In 1800, with nearly one billion people alive, life expectancy at birth did not surpass thirty years. By 2000, with more than six billion people alive, life expectancy reached nearly sixty-seven years amidst a continuing rise. (source). In just 200 short years we have more than doubled the average life expectancy that modern humans experienced for tens of thousands of years.

Today there are 600 million people over the age of 60. And by the middle of this century there will be 2 billion people over age 60. (source).

In Canada, for example, the proportion of seniors in the overall population has gone from one in twenty in 1921, to one in eight in 2001. The growth of the seniors population will account for close to half of the growth of the overall Canadian population in the next four decades (source).

Over the past half a century the global distribution of life expectancy has become less skewed. In 1960 the life expectancy of the world's quintile with the lowest life expectancy was 35.9. This had risen to 53 years by 1999, an increase of 48%, and is 80% of the global average. The quintile with the highest life expectancy went from a life expectancy of 70.1 in 1960 to 76.8 by 1999. This was an increase of 10%, and is 16% above the global average life expectancy (source). Despite serious challenges to increases life expectancy (like AIDS in Africa), a demographic convergence is occurring. Population aging is a global, not local, phenomenon.

(2) Aging is "man made"

There are no "aging genes". Unlike vision, dexterity or memory, which are the product of natural selection, aging is the product of evolutionary neglect. Leonard Hayflick describes aging as an artifact of civilization:

Humans are the only species in which a large number of members usually experience aging. Aging in numbers proportional to those seen in humans simply does not occur in feral animals. It occurs only in the animals that humans choose to protect.

....Because humans, unlike feral animals, have learned how to escape the causes of death long after reproductive success, we have revealed a process that, teleologically, was never intended for us to experience. One might conclude, therefore, that aging is an artifact of civilization. (source)

(3) The Moral Duty to Tackle Global Aging

The fact that populations are aging is a mix of good and bad news. On the good news end of things, global aging is an incredible and laudable accomplishment. A number of important advances -- such as technology (especially the sanitation revolution), medical knowledge, material resources, changes in behaviour, etc.- brought a rapid decline in infant, child, maternal and late-life mortality. Humans have never enjoyed the opportunities for health and longevity that they now enjoy.

However, biological aging, and population aging, bring unprecedented challenges. Aging individuals faced increased risks of morbidity and mortality. Chronic diseases like cancer, heart disease, stroke, arthritis, etc. are set to ravage the aging populations of the world. This means unprecedented numbers of humans will suffer years of frailty and disease. Chronic diseases have replaced infectious diseases as the greatest threat to global health. In the year 2005, chronic diseases killed 35 million people worldwide. 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 combined (source).

Aging populations place ever growing stress on health care and pensions.

So the scientific consensus is in: global aging is real. The data is beyond dispute.

And the scientific consensus on the impact senescence has on our health is in-- it increases one's risk of morbidity and mortality. That data is beyond dispute.

So what are we going to do about global aging? At the end of this century our children and grandchildren will look back and ask:

"What were they thinking? Did they not see how dire the consequences of global aging can be? Did they not care about protecting all future generations from the chronic diseases that ravage humans in late life? Did they not care about passing on the economic benefits of the longevity dividend? Why did they focus so much on very low-risk events, like terrorism or catastrophic global warming, and so little on the most likely of risks-- like the chronic diseases of aging?"

(4) What can we do?

Adaptation, Age retardation and Regeneration

Can we just adapt to global aging? No. There are some external modifications we can make to the our environment to promote the health and happiness of aging populations. We can re-design our cities to make them more hospitable to a population with more limited mobility. We can ensure there are public spaces, such as parks, to help promote the fitness of aging populations. We can encourage the population to keep their minds active to help delay the progression of cognitive decline and mental illness, etc.

But adaptation alone will not stop the tsunami of chronic diseases that await the 2 billion seniors that will exist in the year 2050. So what else can we do?

We can search for ways to directly modify our biology to help mitigate the harmful effects of biological aging. If we developed an aging pharmaceutical, for example, that could mimic the effects of calorie restriction we could slow human aging and this would confer health and economic dividends for all future generations to enjoy by increasing the human healthspan and compressing morbidity. We are closer to this than you might think (see this).

And we could also invest in regenerative medicine and develop new interventions that help aging populations enjoy more health and vitality.

We should be bold and imaginative in our deliberations concerning how to meet the challenges of global aging.

But before we can have a serious debate about what to do to address global aging, we must get our heads out of the clouds and acknowledge the reality of what are the most pressing and probable problems that await humanity this century. And global aging should be at the top of that list.