New medical research into the process of facial flushing and redness has found that individuals with rosacea produce greater nerve, blood flow and sweating responses than people without the disorder when exposed to increased heat or stress.  Results of the National Rosacea Society-funded study also uncovered a role for the sympathetic nervous system, which controls the “fight or flight” response and other key involuntary functions such as heart rate, digestion, breathing and perspiration.

“Heat and stress have long been recognized as rosacea triggers, but it has not been clear what happens in the body to cause these flare-ups to occur,” said Dr. Thad Wilson, associate professor of physiology at Ohio University. “That’s why we devised innovative ways to replicate these triggers in a controlled manner while studying their effects on facial nerves, skin blood flow and sweating.”

 To increase body temperature, the researchers had 10 rosacea patients and 10 healthy control individuals wear a tight-fitting suit lined with tubes carrying water heated to 115°F until their body temperature increased by approximately 2°F.  Each person was then precisely measured for supraorbital nerve activity (a nerve just above the eyebrow that serves the forehead skin), forehead skin blood flow and forehead sweat rate.

The researchers found that rosacea patients had higher skin blood flow and sweating rates compared to normal subjects both before and after the heating began, and their skin blood flow and sweating also began to increase more rapidly during heating.

In a separate part of the study, heart rate, supraobital nerve activity and blood pressure were monitored in 12 rosacea patients and 12 healthy control subjects during mental and physical tasks.  These included performing fast-paced mental subtraction exercises for two minutes, using hand gestures to indicate answers, and tightly squeezing a handgrip for two minutes.

While heart rate and blood pressure were the same between the groups during the hand exercises, skin blood flow was higher during mental arithmetic in the rosacea patients.  The rosacea patients also experienced heightened sympathetic nerve activity compared to those without rosacea during both the mental and physical portions of the test.

“These results indicate that rosacea symptoms may be in part due to sympathetic nerve overactivity,” Dr. Wilson said.  “This is an important area that warrants further investigation, as it may lead to improvements in therapy and trigger prevention.” 

The greater responses in rosacea patients occurred in the sympathetic nervous system, a part of the body’s autonomic nervous system that controls involuntary functions such as heart rate, digestion, breathing and perspiration.  This portion of the autonomic nervous system functions largely below the level of consciousness and has been shown to respond to emotion.