Biohacking. Metabolomics. Transhuman. The world of longevity research is full of strange neologisms. And no real conversation about longevity would be complete without at least one mention of the word healthspan. The popular press (including us) often uses this term to describe the period of life that people spend in good health, free from age-related chronic diseases and disabilities. However, scientists have recently begun to debate the utility of this term in longevity research.
A Brief History of Healthspan
If you were doing longevity research or even somewhat invested in the “anti-aging” market during the 1990s, you probably would’ve never encountered the word “healthspan” Prior to the year 2000, only 14 published papers used the term. But fast-forward to today, and you’ll see nearly 1000 articles with “healthspan” in the title or abstract. Where did this word come from? And why are longevity researchers so interested in it?
Healthspan might seem like the hip new thing to say at conferences, but the term has actually been around for almost 100 years. For example, a study entitled “Extending the Health Span and Life Span after Forty” appeared in the June 1923 issue of the Southern Medical Journal. Although the word has been around for a while, it didn’t really gain traction until the past 30 years or so. To understand why healthspan became popular, let’s take a quick detour through the history of public health.
Public Health and the Public’s Healthspan
In the U.S. and elsewhere, public health initiatives (as we know them today) began to take on different functions after germ theory gained credibility. Germ theory identified microbes as the cause of disease instead of miasmas—or foul odors. When they recognized the presence and power of germs, early 20th century public health officials got to work by quite literally cleaning up the cities.
Over the next few decades, public health extended its reach and began to emphasize things like preventative medicine and social determinants of health. But these institutions still focused primarily on lessening disease transmission and curing acute diseases. In the 1970s and 1980s, researchers began to notice a strange pattern. Although life expectancy was increasing, many populations experienced worsening health.
When people lived shorter lives, they often died from recent infections. Towards the end of the 20th century, researchers noticed a different dynamic at play. Death was generally the result of chronic conditions, which developed over a long lifespan. Although increasing longevity still remained a goal for some researchers, others became interested in making our later years more pleasurable.
And thus, the turn to healthspan began.
When You’ve Lived This Long…
Healthspan, then, is a modern issue. In the past, people rarely lived long enough to develop the debilitating diseases that come with extended lifespans. Many people want to live longer lives, but we should also note how far we’ve come. Longevity researchers sometimes forget to mention that our lives have extended tremendously over the last 200 years. We tend to live as many as 50 years longer than some of our great ape relatives, with whom we share over 99% of our DNA.
That being said, a long life does not equate to a healthy or happy one. This is where healthspan comes in. Researchers are now looking at ways that we can improve not only the quantity of life, but the quality of it as well.
Stop Trying to Make Healthspan Happen
Most people can quickly get behind the whole healthspan idea. “Yeah, of course,” they say. “I want to live for really a long time, but I also want to enjoy my long life by doing the things that I love.” And that’s great! We’re right there with you! But what is the actual usefulness of healthspan in longevity research?
Simply stated, healthspan refers to a period of good health that begins at birth and ends at some subsequent time when an individual is no longer in good health and/or is suffering from age-related diseases or disabilities. “Conceptually, this is a nice definition, as it allows us to consider healthspan as a quantitative continuous variable, in the same way that we consider lifespan,” says a recent article in GeroScience.
Healthspan might be a useful metric for thinking about how genes, social determinants, and epigenetic transformations function together. Despite this trajectory, healthspan would be very difficult to actually study in a lab or clinic. Bioscientific studies that attempted to do so would quickly find themselves up a river with no paddle—or more specifically, neck deep in numbers with no rubric.
In Sickness and in Health
How can we measure “good health”? Is there a line between good health and bad health? Could one person’s bad health be another’s good health? The concept “good health” is highly subjective, and no standard rubric could capture each individual’s understanding of “good health.”
At its core then, the concept of healthspan relies on a strange binary—one in which we are either in good health or poor health. Be honest. How many days out of the year do you wake up feeling completely physically/mentally/emotionally healthy? Or how many days do you feel awful? How often do you feel something in between these extremes? For most of us, much of our lives are spent in the gray areas of good and poor health.
From Health to Healthspan
So where does this leave us in regards to healthspan? Do we trash it or keep it? We should definitely keep it…at least for now. Healthspan reminds us that healthy and happy lives can’t be reduced to elaborate equations. Longevity researchers would be wise to remember that they are dealing with people first and numbers second. From a methodological standpoint, future healthspan research should include scientists, but also cultural theorists, social workers, eldercare patients, television producers, and many others. Health is a multifaceted concept that requires an equally multifaceted approach to adequately grasp. Once we understand health on a personal and local level, then we’ll have a much better chance of improving healthspan on the global stage.