Rosacea and the Sympathetic Nervous System: Dr. Peter D. Drummond, PhD
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Dr. Peter D. Drummond, PhD, Professor in the School of Psychology, Murdoch University, in Perth, Western Australia, has kindly answered a few questions for us on the links between rosacea and the sympathetic nervous system. Dr. Drummond's research interests include the neural control of facial blood flow, and the role of the sympathetic nervous system in pain and inflammation. Dr. Drummond's publications in his field are numerous and include many directly related to these areas of interest:
Because so little is known about possible links between rosacea and the sympathetic nervous system, we asked Dr Drummond if he could talk us through some of the possibilities. The Support group would like to express our deepest thanks to Dr. Drummond for kindly taking the time to help us.
Q: Could you please explain how the sympathetic and parasympathetic both regulate body temperature and impact rosacea, via the hypothalamus, adrenals, heart etc.?
A: The blood vessels of the face are supplied by separate sets of sympathetic nerve fibres that cause the vessels to constrict in the cold or dilate when the body is hot (e.g., after exercise). The vasodilator nerves also control blushing to emotions such as embarrassment and probably anger. During exercise and strong emotions, adrenaline is released from the adrenal glands into the bloodstream, and some finds its way to the facial blood vessels where it causes the vessels to dilate. Adrenaline also makes the heart beat fast and hard. Certain parts of the face (around the eyes, lips, and inside the mouth) are also supplied by parasympathetic nerve fibres that make the blood vessels dilate in response to painful stimulation of the eyes and mouth. It seems more likely that sympathetic vasodilator and constrictor fibres are involved in rosacea than the localized parasympathetic fibres around the eyes and mouth.
Q: What do you think of claimed links between rosacea and SNS disorders such as blushing, excessive sweating (hyperhidrosis) and the inability to sweat (anhydrosis)? How likely is it that repeated blushing will 'tip over' into true rosacea flushing?
A: I'm not sure about a link between blushing and rosacea. Perhaps if the blood vessels dilate easily or stay dilated for long periods when people blush, this increases the risk of inflammation or damage to blood vessels that results in rosacea. People who sweat a lot often flush at the same time because they have an overactive sympathetic nervous system. People who can't sweat need to lose body heat through other means such as flushing. So if flushing triggers rosacea, both excessive sweating and lack of sweating might be linked with rosacea.
Q: What do you regard as the most helpful ways of controlling SNS responses directly related to the emotions, such as nervous blushing, or rosacea flushes triggered by anxiety, etc.?
A: Emotional responses can be controlled to some extent with stress management techniques and anti-anxiety drugs. Beta-blockers might be particularly helpful because they block the direct effects of adrenaline on facial blood vessels.
Q: Since sweating releases bodily heat, when sweating is severely curtailed and the skin can no longer thermoregulate, does the body compensate and regulate skin temperature with flushing capillaries?
A: Yes – also see my answer to [the question about the link between rosacea and SNS disorders above].
Q: Although some rosaceans are still able to sweat freely from all parts of their faces, many have lost the ability to sweat from their rosacea areas. Can facial sweat glands be permanently damaged, eg by over-use of strong topicals?
A: I'm not sure, but a dermatologist might be able to answer this question.
Q: Does severe facial flushing reflect a malfunction of the hypothalamus? Many of our members struggle with beet-red flushes that boil for an hour or more. Others find that even minimal physical exertion can bring flushes, a rapid pulse and other symptoms of heat exhaustion, and this may progress to happening with even less exertion and at ever-lower temperatures. They feel that their 'thermostats' are running out of control and need to be 'reset', but is there any way the hypothalamus can be 'reset'?
A: The hypothalamus is able to measure blood temperature and triggers generalized flushing if this temperature rises above a set point. The set point alters during fevers and can be "reset" with aspirin or paracetamol. I'm not sure whether this would work in rosacea because something other than a fever-causing agent might change the set point. For example, there seem to be many complex influences on the set point, which varies with age, sex, time of day, exercise training, certain foods etc. It would be interesting to explore the set point for flushing and sweating in rosacea.
Q: Is there any connection between the hypothalamus and neuropathic burning triggered by ambient heat, or any activity that raises the person's temperature even slightly?
A: There could well be a connection between body heat and burning pain – the pain is probably due to activation of sensitized sensory nerves that surround blood vessels. Any increase in blood flow through these vessels that heats the surrounding tissue might trigger the burning pain. Activity in the hypothalamus that increases facial blood flow ( e.g., during emotions) could therefore trigger the pain.
Q: Do you think rosacea might be caused by a disruption in the HPA (Hypothalamus-Pituitary-Adrenal) axis, which controls hundreds of bodily functions?
A: This is possible, in theory, although I don't know of any studies that have explored this idea.
Q: How does the inflammation we see with rosacea come into play? Do you feel that problems or disruptions with the SNS and/or HPA axis cause inflammation, or do you think it more likely that the excess cytokines produced under chronic inflammation might instead themselves cause problems with the SNS and/or HPA axis?
A: I'll sit on the fence on this question… I don't know what causes inflammation in rosacea, or what consequences the inflammation might have. Perhaps a vicious circle develops between sympathetic nerve activity, flushing, and products of inflammation in rosacea.
Q: What direction would you like to see future rosacea research heading toward, e.g. genetics, vascular abnormalities, etc? Is there anything happening in rosacea/flushing research that you find particularly encouraging, and do you see anything on the horizon in the near future for us to look forward to?
A: I'm merely a novice in rosacea research, and don't feel qualified to answer this question with any authority. But from my own point of view, I would like to be able to answer some of the questions raised above. I would like to know whether frequent or intense blushing does actually damage blood vessels and, if so, why this sometimes produces chronic inflammation. At the moment, the symptoms are being managed, often by trial and error, using techniques that were originally developed for other medical conditions. I think we need to clarify the basis of the physiological abnormality in rosacea so that a more logical approach to treatment can be developed.