August 27, 2010
Alopecia areata is a mysterious disorder that can cause everything from a barely noticeable loss of a patch of hair to total loss of all body hair, including the eyebrows. When alopecia was recently featured in the Patient Voices series, several readers had questions about the relations between stress and the onset of the disorder. Here, Dr. Maria Hordinsky, a dermatologist from the University of Minnesota, responds.
Stress has been cited frequently as a factor in autoimmune diseases, including alopecia areata. Yet experimental evidence to decisively link stress and alopecia has been lacking.
It is easy to link alopecia with stress, as many but not all patients associate stressful events with the development of hair loss. Moreover, there are a lot of nerves in and around hair follicles. The actions of these nerves, as well as various nervous system products called neuropeptides, could affect the hair growth cycle.
For example, neuropeptides like substance P, a brain chemical involved in pain transmission, could be released from nerves or other cells around hair follicles as part of the inflammatory process characteristic of alopecia, thereby affecting hair growth. Interestingly, substance P has been studied for its effect on the hair cycle in mice. Treatment with substance P was found to stimulate hair growth when given to mice with hair follicles that were primarily in the resting, or telogen, growth phase. In contrast, if the mice were administered substance P when most follicles were in the growth phase, or anagen, there was a premature conversion to the intermediate stage of the hair cycle known as catagen.
In addition to being a highly innervated structure in the skin, the human hair follicle is able to synthesize and secrete cortisol, a stress-related hormone. Cortisol, like other hormones, is regulated by a complex feedback process that starts in the brain and involves glands throughout the body, including the adrenal glands next to the kidneys. The relatively recent finding of an extra-adrenal site of cortisol synthesis in the human hair follicle places the follicle in a unique position to be able to respond to stress.
Many of the girls adversely effected are also suffering from hair loss….Alopecia areata was cited as a possible reason for this in the March 2010 FDA listening session. This article and link to the study further explains this hormone imbalance.