No one dies of old age: what autopsies on centenarians reveal

Come on death certificates often appears “natural causes” or, in older people, simply “old age”. As if at a certain point the body decided to give up for no specific reason. But when pathologists open up those bodies, they discover a different story. There is always something specific that has stopped working: a blocked artery, a heart that has given out, the lungs that can no longer hold up. Never, under any circumstances, simply “old age”.

It is from this observation that Maryam Keshavarz and Dan Ehninger, of the German Center for Neurodegenerative Diseases, began to dismantle some certainties of research on aging. The their study of 2,410 autopsies reveals that Cardiovascular diseases cause the vast majority of deaths: heart attack in 39 percent, cardiopulmonary failure in 38 percent, stroke in 17.9 percent. Among those over eighty-five who died suddenly, cardiovascular events explain 77 percent of cases. Even seemingly fit centenarians: 68 percent died of cardiovascular causes, 25 percent of respiratory failure. None due to “old age”. “Autopsies are critical for correcting misperceptions,” the researchers write. “Relatives and doctors often misjudge causes of death without examining the body.”

You don’t die from old age: a question of species

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Now, if humans almost all die of heart disease, laboratory mice die of cancer. In 84-89 percent of cases. Even when you treat them with rapamycin or restricted diets, which are supposed to “slow aging”, cancer remains there as a cause of death, only postponed. Midges, on the other hand, die from intestinal collapse, worms from infections. Each species has its weak point. And here comes the problem: when a drug extends the lives of mice by stopping cancer, is it slowing aging or just postponing the disease that kills that species? If we don’t die of cancer but of the heart, why should we expect it to work? Keshavarz and Ehninger went to sift through studies on the famous “pillars of aging”, that framework that should explain how we age at a cellular level. Inconvenient finding: Between 57 and 100 percent of these studies tested interventions only on old animals. Which makes it impossible to figure out whether you’re truly slowing aging or simply improving fitness at any age. In the few studies done even on young animals, 72 percent of the improvements were seen in both groups. Which is as if it resets everything. “Despite decades of research,” the two scientists conclude, “we may still not have an understanding of what really drives age-related decline.” Simply put: we know how to describe aging better and better, but not explain it.