By LESLIE KERNISAN, MD
For a while now, I’ve been working on an ebook about making digital health more useful and usable for older adults.
(Don’t hold your breath, I really have no idea when it will be done. I can only work on it for about an hour every weekday.)
In reflecting on the health innovation conferences and conversations in which I’ve participated these past few years, I found myself musing over the following two questions:
1. What is health?
2. What does it mean to help someone with their health?

After all, whether you are a clinician, a health care expert, or a digital health entrepreneur, helping people with their health is the core mission. So one would think we’d be clear on what we’re talking about, when we use terms like health and health care.
But in fact, it’s not at all obvious. In practical parlance, we bandy around the terms health and health care as we refer to a wide array of things.
Actually defining health has, of course, been addressed by experts and committees. The World Health Organization’s definition is succinct, but hasn’t been updated since 1948:
“Health is a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity.”
A more recent attempt to define health, described in this 2011 BMJ editorial, proposed health as “’the ability to adapt and self manage’ in the face of social, physical, and emotional challenges.”
This left me scratching my head a bit, since it sounded more like a definition of one’s resilience, or self-efficacy. Which intuitively seem much related to health (however we define it), but not quite the same thing.
I found myself itching for a definition of health that would help me frame what I perceive as the health – and life – challenges of my older patients.
Also, it seemed impossible to articulate how digital health tools might help us care for an aging population, if one didn’t start with a practical definition of health.
So after doing an hour of research in the literature (and finding endless scholarly rabbit holes), I ended up trying to sketch a model of health that felt true to my experiences.
In this post, I’d like to share what I came up with, and get your feedback. Then in a follow-up post, I’ll write about what this might mean for defining health care, and our efforts to improve or facilitate health care.
What is health?
Health is a dynamic state. For an individual, it involves three core components:
• How are you feeling? How do your body and mind feel? Are you experiencing any pain? Bothersome sensations? Mental distress? This component of health addresses the individual’s experience of suffering.
• How well are your body and mind outwardly working? Are your body and mind working as you expect them to, or need them to, or want them to? Can you get around physically as you usually do? Can you manage your thinking tasks? Can you see, hear, speak, and otherwise communicate effectively with others? This component addresses the individual’s ability to leverage body and mind in order to manage one’s usual activities and life tasks.
• How well are your body and mind internally working? This component relates to one’s inner physiology and function. When we peer inside, whether with modern technology, via the careful pulse auscultation used in some cultures, or any other method, is anything awry? Do we find signs of disease, disorder, or disruption? In Western medicine, we consider the workings of organs and cells, but other cultures have their own “inner workings” that they assess when evaluating health.
These three components are in constant interplay with each other. Right now I’ll refer to them your wellbeing, your macrofunction, and your microfunction. (But I’m not sure those are best terms.)
These three components of health are also in constant interplay with our social and physical environments, as well as with our nutrition and our “lifestyle choices.” For instance, rich social encounters and purposeful work improve wellbeing, as well as immune function and other aspects of our microfunction. Air pollution might make us cough, and can negatively impact our lung function, along with other less visible parts of our health.
Are these many external factors, and our behavior choices, synonymous with “your health”? I would call them influences on your health, or in certain cases “health care”, rather than your health itself. (And they aren’t diagrammed above, although I’d like to add them eventually.) These factors are incredibly important, but we confuse matters when we conflate things that influence health — such as access to clinicians, clean water, walkable cities — with the actual health of an individual.
Why does a person’s health matter?
Better health is an important end in of itself.
But to a large extent, health is a means to a more important end: that of living life.
In other words, being able to do the things we care about, need to do, and want to do. Being able to do things that give purpose, meaning, and pleasure to our lives. Being able to do the things that make us feel like our selves.
This is kind of obvious, but it’s actually fairly easy to lose sight of this when we get immersed in the weeds of health and health care. (Which is why the Unmentionables at Health 2.0 is so fantastic: it’s a much-needed reminder that health serves life.)
[Caveat: There is a lot of overlap between the life activities, but I haven’t yet figured out how to diagram this. Graphic design is not my forte.]
What is a health problem?
As a doctor, my job is to help people address their health problems. And I’d like for the digital health entrepreneurs to create tools that work better for this purpose.
So what is a health problem? How to define what people seem to need help with? How to define what digital health tools should help us – whether we are a patient, a clinician, or a family caregiver – address?
Here is a practical definition: a health problem is anything that is “wrong” with one or more of the three components of health above.
For instance:
• Wellbeing Problems: Examples include being in pain, being fatigued, having insomnia, feeling depressed, feeling anxious, feeling short of breath, and so forth. Many symptoms, pains, discomforts, and any other forms of suffering fall into this category.
• Macrofunction Problems: These might include having difficulty walking due to arthritis, problems exercising due to shortness of breath, or problems thinking due to dementia. You could also include vision problems, hearing problems, and speech difficulties due to stroke. These issues often cause noticeable functional impairments.
• Microfunction Problems: These would include problems such as having impaired glucose metabolism, high blood pressure, osteoporosis, kidney disease, as well as early stage cancer.
You’ll notice that problems with wellbeing and macrofunction are primarily person-defined. It’s the affected person – sometimes known as “the patient” – who experiences suffering, or difficulties in how the body and mind are working. Whereas microfunction problems are generally “expert-defined”: nobody knows they have osteoporosis until clinicians tell them.
Many diagnoses, diseases, or health stressors will cause problems in all three parts of health. For example, cancer symptoms and the related functional impairments (e.g. problems doing anything you can usually do) are the consequence of the cancer cells running amok within.
Congestive heart failure might cause uncomfortable dyspnea, as well decreased exercise tolerance, such that a person has difficulty managing usual ambulation and activities.

Of course, there is a lot of room to argue about what constitutes “wrong” with a given health component. Cultural and social factors influence how people perceive their own suffering, or overt impairments. And we could quibble endlessly about what is ideal blood pressure, and how we might otherwise assess how right or wrong a person’s body and mind are internally working.
Still, in many cases, if most of agree that something seems “wrong” with a given component of health, this should provide us with a decent practical starting point for identifying health problems.
Do we need to distinguish between microfunction and macrofunction?
I believe we do. Problems with macrofunction are the things that people notice in themselves (or in others, when it comes to cognitive macrodysfunction). These are what patients are often most concerned about.
Macrofunction problems, along with forms of suffering, are also what directly impacts people’s ability to participate in life tasks, and their short-term quality of life.
So helping people correct, mitigate, or adapt to these types of functional impairments is incredibly powerful, if you want to address health problems in a way that makes people’s lives materially better. This is an approach that is common in geriatrics, palliative care, physical and occupational therapy, and behavioral therapy.
Microfunction, on the other hand, is what people need technical assistance to assess. (Historically that assistance have been clinicians, but we’re on the cusp of seeing advanced diagnostic tools in the hands of the public.)
Much of the work that we doctors do in modern medicine, especially in primary care, is address physiologic problems that are scarcely perceptible to the affected person: high blood pressure, high cholesterol, type 2 diabetes, kidney disease, asymptomatic atrial fibrillation.
We do this work because we are trying to prevent or delay more overt health problems, such as those associated with suffering and macrodysfunction. So it’s certainly worthwhile work. But it doesn’t always feel satisfying or worthwhile to patients, especially if they are pre-occupied by other problems which are causing suffering or overt functional impairments.
In fact, it seems to be fairly common that patients and clinicians are focused on different aspects of health. A typical example: a doctor might decide to unilaterally prioritize tinkering with the microfunction, such as by prescribing more statins, even though a patient’s most pressing concern is falls or pain.