Is Aging a Disease or a Natural Process


Is Aging a Disease or a Natural Process
11 April

Philosophers have argued for millennia whether aging is a natural process or a disease to be cured. The debate — gaining fresh vigor in recent years with advances in understanding disease causes even while science still can’t explain exactly why or how we age — is full of genuine scientific disagreement, laced with idealistic dreams of immortality, and loaded with ethical concerns.

Biological aging is not just a source, but the source of many debilitating and deadly diseases, argues the Healthy Life Extension Society, led by Sven Bulterijs, a postgraduate researcher who studies the biology of aging at the University of Ghent in Belgium. “The only way to prevent these illnesses linked to aging is to attack the principal cause — aging itself,” the group contends. “It is time to start working toward solutions to this universal human tragedy.”

Those bold assertions, particularly viewing aging as a tragedy, are not shared by the majority of aging experts.

“Aging is a natural part of life for those who are lucky enough to live a long time,” says Sharona Hoffman, JD, a professor of law and bioethics at Case Western Reserve University and author of the book, Aging With a Plan: How a Little Thought Today Can Vastly Improve Your Tomorrow. “Aging should not be considered a disease in and of itself.”

The National Institute on Aging concurs, in what serves as an official scientific stance on the issue, a nuanced view that emphasizes the complex, two-way relationship between aging and illness: “Aging is not, in and of itself, a disease. However, aging is the major risk factor for developing many major chronic diseases. Furthermore, many diseases appear to accelerate the aging process — which is manifested as declines in functionality and reduced quality of life.”

What is disease, anyway?

Among the many loose ends driving this debate is the startling fact that there is no universal, formal medical description for the word “disease.”

The World Health Organization (WHO) defines “health” as “a state of complete physical, mental, and social well-being and not merely the absence of disease or infirmity.” Yet disease is sometimes defined, if at all, only as being the opposite of health. Or it’s defined rather succinctly yet imprecisely as “illness or sickness characterized by specific signs and symptoms.”

Scientists sometimes refer to disease simply as an unwanted or harmful deviation from the norm.

Meanwhile, the list of maladies that are considered diseases is fluid, illustrating ongoing challenges to conventional medical wisdom. Osteoporosis didn’t used to be on the list, but now it is. Homosexuality was on the list, and now it’s not. Whether obesity should be considered a disease is in the midst of its own hot debate.

The argument for defining aging as a disease

The case for characterizing biological aging as a disease argues, in part, that the physical decline that typically comes with chronological aging is harmful and unwanted, just like a disease, and there are specific signs and symptoms attributable to aging, Bulterijs and colleagues wrote in a 2015 article in the journal Cell.

This line of thinking has spurred some change.

In 2018, the WHO added to its disease classification system the notion of “aging-related diseases,” defined as those “caused by biological processes which persistently lead to the loss of organism’s adaptation and progress in older ages.” Examples include cataracts, atherosclerosis, osteoporosis, sarcopenia (muscle loss), and dementia. Age is also now a big factor in broader health states or conditions that aren’t formally termed diseases, including urinary incontinence, frailty, and falls, the agency notes. But the WHO stopped short of calling aging a disease on its own.

By classifying aging as a disease, the fatalistic notion of it being “natural” would, proponents say, be replaced by greater efforts by you and I to adopt healthy habits and take medications that slow the aging process. Plus there’d be stronger efforts to study and treat aging, with support from federal agencies like the National Institutes of Health, which hands out research grants, and the Food and Drug Administration, which decides what medicines can be prescribed for what conditions. Think of how money and effort pour into researching cancer and other chronic diseases, prescribing treatments to battle against them, and engaging the entire health care and health insurance industries in the effort.

“Work to develop medicines that could potentially prevent and treat most major diseases is going far slower than it should be because we don’t recognize aging as a medical problem,” argues David Sinclair, PhD, a controversial anti-aging proponent and geneticist at Harvard Medical School and, it should be noted, a ​​co-founder of multiple biotechnology companies.

“If aging were a treatable condition, then the money would flow into research, innovation, and drug development,” Sinclair says. “Right now, what pharmaceutical or biotech company could go after aging as a condition if it doesn’t exist?”

Downsides to calling aging a disease

Philosophically, calling aging a disease implies it can be cured, just as some people are cured of cancer. That portends a future in which people never die. A cynic might say that such hubris insinuates that life as we know it is not as it was meant to be, that the most universal truth in life — its end — is just a cosmic glitch or a divine error, depending on your point of view, and one that needs fixing.

Logically, getting old is normal, not a deviation from the norm, the majority of experts and institutions agree. Even claims that the typical lifespan can be extended to, say, 150 years or more, are viewed as “very, very unlikely” based on a recent statistical analysis led by Michael Pearce, a doctoral student in statistics at the University of Washington.

Immortality? Almost surely not in your lifetime.

“If aging is a disease, then all 7.7 billion people on Earth have it, and everyone over the age of 65 has an advanced case,” the writer Joelle Renstrom notes in Slate.

Practically speaking, there’s already enough stigma and job discrimination associated with aging, says Hoffman, the Case Western bioethicist, even though “many people remain highly competent and contribute a great deal to society when they are in their eighties and beyond.”

Indeed, some “superagers” have 80-year-old brains that remain virtually indistinguishable from those of twentysomethings. And despite the common perception that time makes us inevitably frail and feeble, it’s well established that engaging in physical activity helps ward off chronic pain and other diseases and promotes mobility and overall physical and mental well-being later in life. Your mileage may vary, of course.

Labeling aging a disease could have the opposite effect that proponents hope for. It could normalize physical or mental decline and foster complacency among aging patients and health care professionals by ignoring or downplaying other important lifestyle choices that can accelerate the aging process, including lack of physical activity but also poor diet, sleep problems, and even retirement, loss of a loved one, and lack of social interaction.

An inaccurate, unhealthy, self-fulfilling mindset could sink in: I’m old, so I’m sick, just as expected. After all, aging is a disease!

“While some diseases are more likely to develop in older age, it would be very problematic to adopt the attitude that natural aging is itself a disease,” Hoffman tells me. “This would reinforce stigmatization and is not accurate.”

Enduring mysteries of aging

One reason this debate still exists: Scientists have yet to pin down exactly why and how our bodies age toward dysfunction, vexing questions given that natural selection generally favors survival and reproductive success. The answers, according to various theories, likely involve at least three interacting processes related to senescence, when cells stop dividing to regenerate and rejuvenate skin, muscles, the brain, and other organs and body parts:

  • Cell divisions can cause genetic mutations that build up, degrading cell function.
  • Each cell division shortens a chromosome’s protective telomeres, until the cell can no longer divide.
  • In their routine work of creating energy, cells also generate waste that can lead to a buildup of damaging molecules.

“These changes are neither linear nor consistent, and they are only loosely associated with a person’s age in years,” the World Health Organization explains.

While aging is inevitable (at least for now) the pace at which any of us ages, or at which certain organs age, is not predetermined nor highly predictable. Several biological, environmental, and social factors, some in our control and some not so much, determine whether and how soon our chronological advancement, on its own or in cahoots with other factors, leads to our demise.

“Aging might predispose to some chronic medical or mental health conditions with other factors playing a much greater role in the disease causation than age alone,” psychiatrist Debanjan Banerjee, MD, and colleagues wrote last year in The Lancet journal.

This leads some to emphasize two aspects to aging: primary, intrinsic aging versus secondary or accelerating aging — that which goes beyond the norm. For example, your skin will age normally, and there’s only so much you can do about it. Spend too much time in the sun, and your skin will age faster, wrinkle sooner, and possibly develop deadly cancer.

This much is clear: People and the cells inside them age at different rates, based on everything from their initial genetic makeup to their physical, social, and family environments to health habits and lifestyle choices, and even whether they fear or embrace getting older.

Pushing for change in aging research

Regardless if aging is ever defined as a disease on its own or not, there are highly practical reasons to study the relationship between biological aging and disease.

Ming Guo, MD, a neurologist and professor of neurology, molecular, and medical pharmacology at UCLA, treats patients with degenerative brain disorders like Alzheimer’s and Parkinson’s. In 2006, with colleagues, she discovered how two genes do quality control in mitochondria, the energy factories inside cells. The findings led to insights into premature aging and its links to diseases of the brain and body, including cancer, diabetes, and heart disease.

“If we could pause, delay, or even reverse aging, we would make a significant impact against numerous diseases,” Guo says. “I want to create a higher quality of life over a healthy life span, rather than just prolonging life.”

Guo sees aging as the natural course of development in humans, as in other animals. “Aging as a whole concept is not a disease,” she says in an email.

But there’s much room for improvement on the research front. With rare exception, there are no reliable ways to measure premature or accelerated biological aging of the whole body or individual tissues, she explains. By changing policies, without labeling aging as a disease, more funding could flow into research that would allow the identification and treatment of premature aging in certain tissues.

One research project on the drawing board, called Targeting Aging with Metformin (TAME), seeks to force such change, Guo points out. It’s aiming for funding from the NIH and approval from the FDA to consider aging not as a disease, but as an “indication” that could be treated. Clinical trials would test the effectiveness on aging of metformin, a drug that was long ago approved by the FDA to treat diabetes.

“If aging is made an indication, the TAME Trial will mark a paradigm shift: from treating each age-related medical condition separately, to treating these conditions together, by targeting aging per se,” the project’s website states.

On the bright side

The debate over whether aging is a disease often ignores positive effects of putting some time under one’s belt.

“Aging confers attributes such as a greater sense of satisfaction, greater resilience, subjective well-being, and wisdom,” Banerjee and colleagues wrote in The Lancet. And, they noted, some diseases tend to lessen with age. “It is evident that various psychiatric illnesses such as bipolar disorder, schizophrenia, panic disorder, and obsessive-compulsive disorder are much less prevalent in old age than in young age.”

Years upon years of living add up to one undeniable fact: We’re all growing chronologically older, and on average, older people are much happier than middle-aged individuals.

If that’s a disease, it’s one most of us might reasonably look forward to.

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