From loose baby teeth to the hormonal throws of puberty to the first strand of grey hair— the human body transforms itself as it ages. For older adults, the process of aging often comes with new aches and pains. With all the symptoms that can accompany age, it begs the questions, is aging itself a disease?

The debate over whether aging should be classified as a disease has taken place within the scientific and medical community for years, but it came to the forefront in 2022 when the World Health Organization released the changes it planned to make to the International Classification of Diseases (ICD), a catalogue used to standardize disease diagnosis worldwide.

In the revisions, the diagnosis of “senility” was replaced with “old age.”

The change prompted both praise and criticism. Researchers in favor of age being classified as a disease said the revision would allow them to create and distribute more anti-aging therapies — and do it with more funding because of the disease classification.

Those in favor of classifying aging as a disease compare it to obesity, which was officially designated a disease in 2013 by the American Medical Association.

“Obesity, just like aging, does not comply with the traditional defining characteristics of disease,” wrote Dr. Sven Bulterijs, et al, in a 2015 article supporting the classification of aging as a disease. “But yet to target an issue such as obesity, categorizing it as a disease makes the road to developing treatment a much easier one to take. As aging appropriately fits the definition of disease, there is a shifting consensus that aging should be seen as a disease process in itself, and not a benign progression of age that increases the risk of disease.”

Supporters also say that the healthcare system ignores aging as the natural cause of some chronic illnesses that affect people later in life, which causes 32% of Medicare spending to go to end-of-life care that doesn’t not effectively improve a patient’s quality of life.

“Even minimal attenuation of the aging process by accelerating research on aging, and development of geroprotective drugs and regenerative medicines, can greatly improve the health and well-being of older individuals,” Bulterijs wrote.

But critics warned that if aging were a diagnosable disease, it could lead to inadequate care from physicians, because it would assign one cause to symptoms that could have many sources.

Bruce Troen, M.D., director for the Landon Center on Aging at University of Kansas Medical Center, echoes these concerns. If a patient’s symptoms are chalked up to simple aging, physicians might miss the real cause of the patient’s issue, he said.

"People think, ‘well, I'm old, I should have a bum knee, or I shouldn’t be able to hear as well.' It’s all about functional ability and quality of life."

- Bruce Troen, M.D.

For example, falling, a syndrome Troen frequently encounters with patients, can have many causes, such as stroke, irregular heart rhythms, syncope, dehydration, or a combination of issues. Cognitive impairment is another syndrome that comes with a whole host of potential causes, Troen said. It can be the sign of something more serious, like Alzheimer’s disease, or it could be improved by changing the patient’s medications.

“When you have something that has multiple causes, then you have to have multiple approaches to your interventions,” Troen said. “Classifying aging as a disease might put limits on those interventions.”

Another hurdle of classifying old age as a disease is the matter of where to draw the line. Everyone is aging every day, but for something to be classified as a disease, there must be a loss of function in some way, said Russell Swerdlow, M.D., director of the Alzheimer’s Disease Research Center.

“Everybody, as they age, is going to lose the ability to do certain things that they used to enjoy doing,” Swerdlow said. “One could argue that aging can then be a disease, if it impairs function, but you run into this issue of — that’s everyone. To be considered a disease, would it have to be a loss of function that wasn’t otherwise inevitable? Then, how do you measure that? The line becomes arbitrary.”

Because aging is something that everyone who has lived a long life has experienced, the idea that aging could be cured like a disease seems almost too good to be true. Those who support classifying aging as a disease say that the change would prompt a huge increase in funding for aging research and the development of biomedical procedures that could eventually solve aging.

“Currently, our treatment options for the underlying processes of aging in humans are limited,” Bulterijs wrote. “However, with current progress in the development of geroprotective drugs, regenerative medicine, and precision medicine interventions, we will soon have the potential to slow down aging.”

But solving aging is easier said than done. Curing aging would mean halting the natural processes that affect all living creatures, which would require massive advancement and discovery.

“Aging is not a disease any more than adolescence is— it’s something that happens to all of us as we get older, and it's a matter of things changing in our body,” said Jessica Kalender-Rich, M.D., a geriatrician and professor at University of Kansas Medical Center. “And those things might affect us differently than they affect our neighbor, in the same way that would happen in adolescence. But it's not that aging, per se, is a disease.”

Because of the vastly different ways aging can affect people, Kalender-Rich said, it doesn’t make sense for a disease to be based solely in a person’s age.

“Age is just a number— it really is. We all know a 50-year-old who can't walk up two flights of stairs, and we all know an 80-year-old who walks two miles a day. You just cannot determine health based on someone's age,” Kalender-Rich said. “Really, the measure of someone's health is based on their independence and their stamina, and whether or not they have medical frailty. That's the thing that matters.”

Troen said the disconnect among doctors about whether aging is a disease could come from a difference in focus. Specialists like cardiologists and pulmonologists are focused mainly on one organ and the diseases associated with that organ. But Troen and his fellow geriatricians are more often taking a holistic view by focusing on syndromes, like falling or dementia, rather than specific diseases.

Rather than focus on aging as a disease, Troen focuses on two things: resilience and frailty. If a person is frail, they have trouble completing some basic daily tasks, like going to the bathroom, getting dressed, feeding themselves, or showering, and they may also have cognitive issues. Frailty is associated with a higher mortality risk, and a higher risk for chronic illnesses and hospitalizations.

On the other side of the coil is resilience — a person’s ability to bounce back after a health setback, such as a fall, hospitalization, or illness. When resilience is diminished, it can lead to frailty, Troen said.

“We’re trying to bring together multiple elements to help make a patient more functionally capable— that doesn't necessarily mean curing a disease,” Troen said. “And many diseases in older adults can't be cured, they must be managed.”

WHO ultimately decided to revoke the revision, and the most recent 11th version of the ICD was released in January 2022 with no language to suggest that aging is a disease. But if classifying aging as a disease isn’t a solution to improving health outcomes for older adults, then what is? For Troen and his fellow geriatricians, it’s a multifaceted approach.

“Our goal is to really identify what matters most to that patient and then to see how we can maximize their mentation, medications and mobility in order to get them as close to what matters most as possible,” Kalender-Rich said. “That’s our North Star.”

The nuanced, holistic approach used by geriatricians is essential to the care of older adults, Troen and Kalender-Rich said. But there aren’t enough specialists in the field to treat the rapidly aging population of the U.S.

In 2019, the population of people aged 65 and older numbered 54.1 million, representing 16% of the population, according to the U.S. Census Bureau. By 2050, the number of older adults is expected to grow to almost 90 million.

There are over 7,000 geriatricians working in the U.S. today. Federal models estimate that one geriatrician can care for about 700 patients. By that metric, the U.S. will need over 33,000 geriatricians by 2025.

But there just aren’t enough fellowship opportunities to produce that many clinicians, said Candice Coffey, M.D., geriatric medicine fellowship director for the University of Kansas Medical Center. Of the 400 geriatric fellowship spots offered every year, about half are usually left unfilled, Coffey said.

“You can't wave a magic wand and change that overnight,” Coffey said. “But what we can do, and what we do here, is that we're constantly doing our best to show students and residents that the life of the geriatrician is a good, good life.”

University of Kansas Medical Center’s geriatric medicine fellowship program lasts one year and has seen its graduates go on to do everything from practice in VA hospitals to palliative care to clinical research, Coffey said. While some fellows do become practicing geriatricians, Coffey said it’s a fellowship that can also compliment students’ other interests, if they want to explore beyond geriatrics.

The oncoming wave of older adults who need care is why Kalender-Rich and Troen want to see systemic changes implemented to improve the care of older people.

“We want cardiologists, for example, to think differently about their 80-year-old patient than they do about their 50-year-old patient, and not because of age necessarily, but because of the underlying things that just truly change as our body gets older,” Kalender-Rich said.

The Age-Friendly Health Systems model, created by the John A. Hartford Foundation in 2017, hinges on the four Ms: what matters (to the patient), mentation, medication, and mobility. Kalender-Rich said the University of Kansas Health System will launch a pilot of the model in 2024.

Models like this can help older adults in a number of ways. They work to make communication easier across providers, so information is shared more widely between members of a patient’s care team and establish practices and policies with older adults at the forefront.

“The idea of things like the Age-Friendly Health System is working closely with our interdisciplinary teams to really create systems of care,” Kalender-Rich said. “Clearly there aren't enough geriatricians to go around, but systems of care can support our partners and our colleagues out there, so that they to feel like they have the resources that they need to optimize the care of older adults.”

Troen is also looking to expand geroscience research by applying to NIH to create a COBRE (Center of Biomedical Research Excellence) for successful aging and resilience at KU Medical Center.  Geroscience is the interdisciplinary field that aims to understand the intersection of basic aging biology, chronic diseases and disabilities, and health in older adults to ultimately improve functional capacity. This would bring additional funding and resources to the university and allow for more collaboration among investigators who are researching aging and aging-related diseases.

“People think, ‘Well, I'm old, I should have a bum knee, or I shouldn’t be able to hear as well,’” Troen said. “No, it doesn't have to be that way. We don't have to accept that. It’s all about functional ability and quality of life.”