When your doctor orders some diagnostic tests, there are two types of information she may be looking for: either acute or chronic. For example, if you have diabetes, either type 1 or 2, it is important to keep on top of your blood sugar levels on a daily basis. But this measurement gives your doctor only an instantaneous reading, a narrow window into your blood sugar control. But what about the long-term blood sugar control? It is important to know it, because the damage caused by hyperglycemia is cumulative and long term, not instantaneous. For that we have the hemoglobin A1C test, which reflects glucose control over 3 months.

Stress: friend or foe?

It depends. The most useful way to differentiate between “good stress” and a bad one is to examine the biological effects of stress. When our ancestors faced a saber-toothed tiger they most likely experienced acute stress and ran for their lives. If they didn’t, we wouldn’t be around to tell the tale. This flight reaction (they would be foolish to fight) was triggered by the stress hormone cortisol, which in turn caused a massive increase in adrenalin (or epinephrine), diversion of blood supply from the gut and reproductive organs and increased blood pressure and heart rate. After all, you’d better not think of digesting your last meal or having sex in these dire circumstances. Everything is dedicated to provide the muscles with maximum blood supply to better to make a quick getaway.  Another fascinating response to acute stress: an elevation of inflammatory mediators like IL6 and TNFα (for the record, these stand for interleukin 6 and Tumor Necrosis Factor α). Why is inflammation so important as to rise under acute stress? Probably because it is necessary to fight infection and mobilize the cells and proteins required for wound healing, just in case the tiger did manage to get in a bite. Speaking of intelligent design…

Modern life has created a multitude of unwanted consequences, primary among them –chronic stress. We all know it first hand: toxic personalities in the office, anxiety about job security, disappearance of your 401K pension plan, or caring for a chronically disabled family member. A paper in the Proceedings of the National Academy of Sciences documented the long-term rise in IL6 in people who took care of parents with Alzheimer’s disease, even years after they died. Such chronic inflammation can manifest itself in a variety of autoimmune diseases such as rheumatoid arthritis, inflammatory bowel diseases (ulcerative colitis and Crohn’s disease), hypertension, atherosclerosis, heart disease and stroke.  

How do you measure stress?

In order to understand and treat a disease we have to be able to measure it in some way. We measure blood sugar and hemoglobin A1C, and treat diabetes accordingly. So how do you measure chronic stress?

The answer is that right now we can’t. Cortisol can fluctuate wildly during the day. A dog is barking at you during your morning run, and a squirt of cortisol is released from the adrenal gland into the bloodstream. The dog is wagging his tail and exudes friendliness- your cortisol level plummets. Such innocuous occurrences happen many times during the day, and measuring the cortisol response to them is hard, and meaningless. To measure cortisol over the long run we need something like the hemoglobin A1C for diabetes; a measurement that will integrate the total cortisol response over a long period of time.

In a recent paper in the September issue of the journal Stress Professor Gideon Koren of the University of Western Ontario describes an ingenious experiment. Substances like cortisol, which get released into the bloodstream when you’re stressed, can get into the hair follicles from the capillaries in the skin of the scalp. As the hair grows, traces of cortisol get trapped in the shaft, providing a way to measure the hormone over time. Because hair grows about 0.4 inches (1 centimeter) per month, most people have many months’ worth of records of cortisol levels sitting on top of their heads. Previous measures of cortisol in blood or urine could record only a few hours’ or days’ worth of the hormone. This method can provide a profile of the cortisol levels over a period of several months, depending on the length of the hair. A major question was how long can cortisol persist in the hair. Not to worry; in several Peruvian mummies it was preserved up to 1,500 years!

Armed with this knowledge, Koren took hair samples from 120 men with a history of either heart attacks or chest pain and infections. Men were the only candidates in the first of what Koren hopes will be several studies, since they are more likely to have experienced heart-related stress.

Members of the research team analyzed the 1.2 inches of hair closest to the scalp, and using the cortisone level measurements they built a “stress record” covering the previous three months for the subjects in the study.

The study confirmed Koren’s theories. Subjects who had experienced a heart attack showed significantly higher levels of cortisol in their hair. All the men in the study showed higher than average cortisol levels; about one third of the men with the lowest levels had experienced heart attacks, while heart attacks were experienced by more than two thirds of those with the highest levels of cortisol in their hair.

What’s next?

Obviously, this study is far from definitive. A larger study, including men and women, and experiencing different types of stress, is required. Assuming that these results are confirmed, hair analysis of the “stress record” would be invaluable in the rational treatment of stress, be it physical or psychological. Think of its effect on the social acceptability of smoking pot….

It could also serve as a wonderful resource in many Ph.D. theses in sociology.

  • Wouldn’t it be nice to measure the stress records of the unemployed? Some people of a certain ideological persuasion argue that the unemployed actually enjoy being unemployed. The proof will be in the hair.
  • Or how about the recent phenomenon of violent political speech by some tea aficionados? Is it rooted in blind hatred, or in deep and abiding anxiety? Psychologists can theorize all day long –a simple hair analysis will settle the argument.

Prospective Ph.D student who would like more ideas –feel free to contact me; I am anxiously awaiting your calls.

Dov Michaeli, MD, PhD
Dov Michaeli, MD, PhD loves to write about the brain and human behavior as well as translate complicated basic science concepts into entertainment for the rest of us. He was a professor at the University of California San Francisco before leaving to enter the world of biotech. He served as the Chief Medical Officer of biotech companies, including Aphton Corporation. He also founded and served as the CEO of Madah Medica, an early stage biotech company developing products to improve post-surgical pain control. He is now retired and enjoys working out, following the stock market, travelling the world, and, of course, writing for TDWI.