A Halt to Progress?

It’s no secret that lifespans have been getting longer—whether in the U.S. or in other developed countries. Whereas at the beginning of the 20th Century global life expectancy rarely exceeded 50 years, it has now reached an average that’s regularly in the 80s in Japan and Canada —and in the United States it’s reached a high of 78 years.

The reasons for this dramatic increase are numerous, and largely have to do with the extraordinary evolution in medical technology, healthcare, and general standards of living that occurred during the 20th Century and continue in the opening decades of the 21st. Vaccination programs have defeated smallpox, polio, measles and other diseases that formerly carried off thousands. Meanwhile, the decline in smoking and the creation of new drugs to ameliorate blood pressure and cholesterol have warded off the ubiquitous specter of heart disease.

The projected percentage change in the world's population by age, 2010-2050. Credit: United Nations, World Population Prospects: The 2010 Revision.

So why does life expectancy seem to be leveling off? What’s undoing—or at least matching, move-for-move—the recent remarkable gains in lifespans? Incredibly, the culprit this time isn’t some virulent pathogen, some unexpected new cancer or disease epidemic; nothing so terrifying as that at all. It’s obesity—a “lifestyle disease” brought on by our unhealthy dietary habits.

And this one’s a great deal tougher to defeat than those earlier epidemics. You can’t vaccinate it away; you can’t inoculate a person against further occurrences. Obesity undoes virtually every gain made in the fight against heart disease and stroke—it raises blood pressure, cholesterol, and heightens the risk for diabetes.

This all brings up some disturbing questions: have we reached the end of the line when it comes to living longer and healthier lives? Is there a point at which diminishing returns just mean any gains in lifespan are bound to be insignificant and temporary?

The Future of Longevity

The answer, fortunately, is probably not. Geriatric medicine has come a long way, and promising headway is being made in research into geroprotective drugs and compounds such as carnosine, the diabetes drug metformin, and the fungal compound rapamycin—an immunosuppressive which seems to induce cells to husband resources, thereby stretching cellular lifespans and by extension the health and life expectancy of the entire organism.

Meanwhile, there are great strides to be made in combating Alzheimer’s, the neurodegenerative disorder that is the great scourge of the elderly. Even if obesity hadn’t arrived to level off the gains made against cardiovascular disease, there’s still that fearful wall to healthy aging erected by dementia. But research into tau proteins and amyloid beta proteins, and drugs like verubecestat and the anti-inflammatory NTRX-07, have shown great promise.

Even if none of these treatments represent the hoped-for panacea for aging, they seem to be pointing in the right direction. Some combination of them, or of future incarnations developed from research into their effects, is likely to greatly extend human lifespans in the future, and—more importantly—allow those greater lifespans to be healthy and productive.

However, the way in which we choose to live those longer lives is another matter altogether. Unhealthy choices will come back to haunt us later in life, and the diseases of obesity and poor diet can still undo all the miraculous and marvelous technology we devise to stave off the inevitable.

Unfortunately, no cures for a self-destructive mentality are anywhere on the horizon.

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