Scratching the surface of skin's mind-body connection

San Francisco - Anecdotal evidence has long supported the notion that a person's mental health can impact his or her physical health and that psychological stress can have real physiological affects.

"But there has always been a little skepticism as well," because it has been so difficult to rigorously document this mind-body connection, Kenneth R. Feingold, M.D., says.

Part of his research focuses on the role of glucocorticoids secreted during both physical and psychological stress and how they affect the skin. Previous work by Dr. Feingold and others has established that psychological stress inhibits epidermal proliferation, decreases epidermal differentiation, impairs permeability barrier homeostasis and reduces stratum corneum integrity and cohesion.

In the latest study in Dr. Feingold's lab at the Veteran's Affairs Medical Center in San Francisco, small groups of hairless mice were subjected to "a very extreme form of psychological stress" for 48 hours - continuous strong light, loud music, cramped conditions, no room for physical exercise.

One group of mice was given RU-486, which blocks the action of glucocorticoids, while another was given antalarmin, an inhibitor of corticotrophin-releasing hormone production that blocks the increase in glucocorticoids occurring during times of stress.

Dr. Feingold found that both approaches were able to decrease the effects of excess glucocorticoids and prevent the skin abnormalities that were seen in other psychologically stressed animals.

"We've demonstrated that psychological stress affects cutaneous function. It is not just in people's minds; it really does occur - you can see it in these animals. And we have at least one mechanism for how that signaling is occurring," Dr. Feingold says.

He readily concedes, "I'm sure that this is not the only mechanism by which psychological stress affects the skin; there probably are other changes that occur via other signaling pathways from the brain to the rest of the body. But this begins to open up the whole field. It had been very nebulous, and now it is becoming much more measurable and believable."

Effects on the skin

Dr. Feingold says the mice that were used all had the same genetic and environmental background, so there was little variability between them.

He hesitates to extrapolate the stress they experienced to what a human might experience. The purpose of the study was to demonstrate a mechanism of action, not replicate a human condition.

He says each human has a different genetic and environmental background and responds differently, so "What is stressful to you may not be stressful to your friend."

"We're trying to define how psychological stress affects normal skin," Dr. Feingold tells Dermatology Times. "Once we understand that, studies in disease models will be interesting.

"One hopes that people will realize that this is an early step in understanding how psychological stress affects your brain and, thereby, alters the function of the skin. In an earlier paper we used a drug that works in the brain to reduce stress - chlorpromazine - and were able to reduce the effect of psychological stress on the skin of the animals."

Dr. Feingold says there is no simple predictor of how increased production of glucocorticoids affects disease states.

"In some instances, high levels of glucocorticoids could be beneficial; they are used to treat certain inflammatory diseases," he says. "On the other hand, high levels can adversely affect skin function, so that they may adversely affect other disease states.

"So, it's hard to tell precisely how these observations will relate to a disease like psoriasis. It will depend on a lot of factors and the balance between these various factors," he says.

There is also tremendous variability between patients, which is why the practice of medicine remains as much an art as a science.