For nine years each autumn I’ve raked the oak leaves and acorns along our walk, but until this week I never thought I’d seen an oak flower—and never wondered if oaks even had flowers. My capacity for curiosity about trees is only coming to me late in life. So this week I swept up a wheelbarrow full of flimsy yellow strands from our walk. What are these, I finally wondered? My app for identifying the mysteries of nature told me of course oaks have flowers, even if these flimsy “catkins” look nothing remotely like any flower I’ve ever seen. Now I can see these catkins as male oak flowers because I finally asked the question.
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Earlier this month in a workshop for primary care clinicians we each used an ultrasound wand to find moving pictures of the gall bladder and inferior vena cava inside one of our colleagues, who had bared his belly for us. For these invisible marvels—babies in utero are the most marvelous—primary care clinics increasingly offer this magic wand of ultrasound to see that deep.
But a wand could not help us see something as enormous and invisible as global warming. For decades climate scientists pitched one finding after another, and still most of the world could not see the problem, or would not. Al Gore and others groped with how to capture the attention of the unseeing. Should we define global warming by rising CO2 levels, by rising ocean levels, or by the alarming number of severe storms? None of these measures carried the impact of the one summary measure that we can all make sense of: average global surface temperature from year to year. The graphs that show global temperatures steadily rising over the past century are easy to see and hard to ignore. Sometimes we need the right measure to see a problem and its meaning.
Over the past five years I’ve been working on a book about stress and illness. The topic fascinates me partly because it requires me to help readers see something that is as invisible as your gall bladder and as hard to grasp as global warming. Modern medicine struggles with a reluctance to see the stress response system in daily action, partly because we lack the right measures.
Each of us lives with a stress response system that is, though not as large, at least as complex as our planet’s surface ecology. It’s a complex system composed of many subsystems, all finely coordinated with each other when we’re healthy. But toxic stress at times can overwhelm our stress response systems and lead to disease or early death. When asked about how stress affects chronic illnesses, most physicians pivot or dodge because they don’t measure stress. Though modern medicine has many measures for some of the components of our stress response system (body temperature, EKG, EMG, lung scans, comprehensive metabolic panels, MRI scans of every organ), we don’t have a good measure for the whole stress response system that tells us when and how it’s failing.
Most physicians don’t worry about this lack of a good measure of stress responses. They’re too busy dealing with the surfeit of measures they already have. But I think we’re missing something, and it’s not trivial. In fact, it’s so big that until recently we have not had the capacity to measure the many dimensions of the stress response system—it’s a problem for “big data.” It’s now possible to collect and manage the big data necessary to understand the stress response system, but can we do it in the rush of clinical practice?
Five years ago, after wondering about why we don’t measure stress in primary care clinics, which is like wondering why oak trees don’t seem to have flowers, I gathered a group of health psychologists and physicians to help me figure out what would be the best way to start measuring stress in ways that could help patients in primary care, where most stress-related conditions get treated. Last month we finally published our review. Our main finding, a humble step back from where we wanted to be, is that we don’t yet know enough about how to measure stress to make recommendations for clinical practice. The best we could do was recommend a set of studies that will help us answer that question.
As with climate science, stress neuroscience has plenty of promising measures to study: the distress thermometer, the perceived stress scale, cumulative life stress, resting heart rate, heart rate variability, allostatic load index, telomere length, biological aging, and social determinants of health, to name a few. They all have their value and their limitations as summary measures.
If I had to choose one among these that could surface as the eye-catching summary measure that will grab the attention of patients and clinicians, it’s the measure of biological aging based on DNA-methylation patterns. Like average global temperatures from year to year, this measure of biological aging has the potential to give us a simple number that could capture the way stress accelerates aging and disease. We all know our calendar ages. Soon we all may know our biological ages too.
Imagine how you would react if during your routine check-up at 40 your primary care physician told you that your biological age was already 53, and accelerating? And at 45 your biological age was now closer to 65. How would that grab you? There’s a lot of science needed to fill in the blanks before we can make this kind of conversation a reality, but it’s not too soon to start searching for better ways of seeing our stress response systems as they slip into trouble. Learning to see DNA-methylation patterns on our genes is like learning to see oak flowers—suddenly we can understand the life of a tree, and the tree of life.