We’ve been thinking about healthy aging wrong, researchers say.
By Nathan Collins
(Photo: Habib M’henni/Flickr)
Although researchers are paying closer attention to mental health than ever before, our usual notions of healthy aging are still very centered on pathology—that is, diseases like cancer, diabetes, or hypertension. A new study suggests that, whether a person is healthy or not is a more complicated matter, and it has little to do with age.
“Health has long been conceived as not just the absence of disease but also the presence of physical, psychological, and social well-being,” write Martha McClintock and her colleagues in Proceedings of the National Academy of Sciences. “Nonetheless, the traditional medical model focuses on specific organ system diseases,” such as heart problems, diabetes, or cancer.
Of course, any concrete, measurable notion of health is going to involve some tough choices. The trouble, McClintock and her colleagues write, is that the current default definition is based on century-old medical ideas that center on pathology, physiology, and biochemistry. That antiquated definition presents two distinct problems. First, it frames ill health as a failure of a particular system, such as the kidneys or lungs. In reality, multiple systems fail at once when people, particularly the elderly, are sick. Second, that definition largely ignores other factors that matter for health, such as exercise, clear vision and hearing, and mobility.
“A shift of attention is needed from disease-focused management, such as medications for hypertension or high cholesterol, to overall health.”
In search of a better definition of health, the researchers put together a list of 54 key health questions, including everything from a blood pressure measurement to an odor identification test, and posed those questions to 3,005 people between the ages of 57 and 85 as part of the National Social Life, Health, and Aging project.
Then, rather than somehow weighting and averaging all the responses to form their own, idiosyncratic measure of health, McClintock and her colleagues took an unusual step, at least for health-care researchers: They implemented a statistical technique called finite mixture modeling. The idea, roughly, is that there are underlying types of more or less healthy people, and that each person falls into one of these types (or, more generally, some mix of types). Finite mixture modeling is a way to recover the underlying types based on data from real people—in particular, from their answers to the team’s 54 health questions.
The analysis revealed six surprising health categories. Older adults in robust health fell into two categories, which the researchers labeled, tellingly, “robust obese” and “one minor condition.” People identified as “robust obese” were generally overweight or obese, had high blood pressure, and had the least chance of death or incapacitation five years after they were first interviewed—just six percent. In contrast, the “one minor condition” group included normal-weight people with relatively minor health conditions such as stomach ulcers, anemia, or perhaps skin cancer—and, weirdly, they had about a 16 percent chance of death or incapacitation over five years.
At the other end of the spectrum, there were “diabetes, hypertension, and immobility,” and “extensive multimorbidity and frailty,” which are about as bad as they sound—the five-year mortality and incapacitation rate for the latter group was 44 percent—though the middle groups might be the most interesting: “broken bones” and “poor mental health.” People classified in the latter group had a 19 percent chance of dying or becoming incapacitated over the next five years, equal to the rate for the “diabetes, hypertension, and immobility,” though apparently for very different, historically underappreciated reasons.
Curiously, age had little to do with the categorization scheme. The “robust obese” group was 2.5 years younger than average, and the “extensive multimorbity” group was three years older, but otherwise there were no differences in age.
“From a health system perspective, a shift of attention is needed from disease-focused management, such as medications for hypertension or high cholesterol, to overall health, especially for mental health concerns, sensory function, and mobility,” the researchers write. “[T]aking a broad definition of health seriously and empirically identifying specific constellations of health and comorbidities in the U.S. population provide a new way of assessing health and risk in older adults living in their homes and thereby, may ultimately inform health policy.”