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Perspectives on Research

Hair Cortisol: A Potential Biomarker of Emotional Distress among Persons with Traumatic Brain Injuries

By David B. Arciniegas, M.D.
In our National Institute on Disability and Rehabilitation Research-supported study of acceptance and commitment therapy (ACT) for the treatment of emotional distress among persons with traumatic brain injuries (TBI) in the subacute and chronic recovery periods, we are performing a pilot study of an innovative method of assessing a physiological correlate of emotional distress through sampling of cortisol levels attained from hair samples of the study participants.

Chronic psychological stress produces similarly chronic over-activation of the body's stress-response system. Cortisol is a component of that stress-response system, the levels of which are increased during periods of high stress. Although short-term increases in cortisol can help the body manage illness or injury effectively, long-term increases in cortisol levels are associated with a broad range of adverse health effects that compromise physical and emotional wellbeing and function. In the context of TBI, long-term increases in serum cortisol levels may, quite literally, add insult to injury.

Hair cortisol sampling enables evaluation of the average levels of serum cortisol produced over the month preceding sampling. Cortisol circulating in the bloodstream is incorporated into hair at the time it is produced by hair follicles. Once it is incorporated into the hair, it does not diffuse out of it as hair grows or as it is exposed to the elements or hair products (e.g., shampoo, conditioner). As a result, the amount of cortisol in the hair serves as a stable marker of the average levels of cortisol circulating in the blood at the time during which that hair is produced.

For the vast majority of people who have hair on the scalp vertex – the very back of the top-most part of the head – that hair is produced at a rate of about 1 centimeter per month. Measuring the amount of cortisol in a 1 cm sample (50 to 100 strands of hair) allows us to estimate the average daily levels of cortisol circulating during the month over which that segment of hair was produced. When that 1 cm hair sample is taken from the segment closest to the scalp, hair cortisol levels provide an estimate of the average daily levels of circulating cortisol during the month preceding sampling.

The sampling method is cosmetically benign, and is usually unnoticeable to even the most appearance-conscious individuals. To put a sample of 50 to 100 strands of hair in context, most people lose at least 50 to 100 hairs from their head every day. Accordingly, most people do not notice a loss of hair in this amount when the sampling for hair cortisol level determination is performed. Additionally, the sample is obtained by making a part in the hair (for those wearing their hair long enough to part) and by using thinning shears to obtain hairs at the base of the part. The use of thinning shears leaves cosmetically unchanged the area under the parted hair from which the sample is taken.

Using this cortisol sampling method, we will be evaluating the correlation between hair cortisol levels among persons with TBI and scores on the Brief Symptom Inventory 18 (BSI 18). The BSI 18 is a short, self-report assessment of depressive, anxious and physical symptoms that are common among persons experiencing emotional distress, including persons with TBI. The BSI 18 asks participants to report on the levels of symptoms they experienced over the last seven days. We will be asking the group of participants in the hair cortisol portion of our study also to report on their level of symptoms over the last month.

If we observe a correlation between proximal 1 cm segment hair cortisol levels and BSI 18 scores, then we will have identified a biomarker of emotional distress among persons with TBI. This biomarker will help us understand the biological effects of emotional distress by providing us with a quantifiable estimate of the level of activity of the immune system associated with emotional health/distress. It also may provide a biomarker with which to evaluate the biological effects of psychotherapy, including ACT or medications, for depressive and anxious symptoms among persons with TBI. In other words, measuring hair cortisol levels may facilitate identification of the neurobiology of emotional distress and the effects of psychological and pharmacologic treatments on the body's stress-response system.

The NIDRR-supported study of ACT for emotional distress among persons with TBI is in its very early stages. When we begin enrolling participants, we also will begin the hair cortisol-sampling component of that study. We anticipate acquiring data sufficient for testing of the relationship between hair cortisol levels and BSI 18 scores in the next one to two years. Once analyzed, these data will be submitted for peer review and possible publication in a brain injury rehabilitation-oriented journal.

David B. Arciniegas, M.D., is senior scientist and medical director for brain injury research at TIRR Memorial Hermann and executive director of the Beth K. and Stuart C. Yudofsky Division of Neuropsychiatry and professor of psychiatry, neurology and physical medicine and rehabilitation at Baylor College of Medicine. He is co-investigator in a novel innovative preliminary investigation of the effectiveness of acceptance and commitment therapy (ACT) for reducing emotional distress, improving health-related quality of life and increasing participation in the community for persons with TBI. If the study is successful, it will provide a foundation for future multicenter comparative effectiveness trials in which ACT can be evaluated in comparison to traditional cognitive behavioral therapy and psychotropic medications. The principal investigator of the trial is Angelle Sander, Ph.D., director of the Brain Injury Research Center (BIRC) at TIRR Memorial Hermann. Additional co-investigators on this project are Mark Sherer, Ph.D., ABPP, FACRM, director of research and director of neuropsychology at TIRR Memorial Hermann, and BIRC researchers Kacey Maestas, Ph.D., and Allison Clark, Ph.D. Please contact Dr. Arciniegas at david.arciniegas@bcm.edu with questions or comments about the hair cortisol aspect of the ACT study.