Researchers at Johns Hopkins University say they have identified a possible cause of hyperhidrosis, a condition that causes excessive sweating in an estimated 15.3 million Americans.
Hyperhidrosis occurs when the body produces significant amounts of sweat without an obvious trigger like heat or exercise. Patients describe sweat so excessive it soaks through clothes or drips from their hands, forcing them to change clothes repeatedly throughout the day.
For years, the condition has been viewed largely as a disorder of the sweat glands. But the new research suggests it may instead stem from a genetic mutation affecting the nerves that control those glands.
"Our findings show that, for some patients, the problem actually begins in the nerves that control sweating," said Dr Malcom Brock, the surgeon who led the research. "This biological explanation for the condition offers a potential pathway to more effective treatments."
The study, published in Science Advances, involved researchers collecting DNA from families with inherited hyperhidrosis and comparing the data. They found that one fifth of sufferers had a mutation on the SCN10A gene, which codes for the sodium channel NaV1.8 found in nerves that control sweat gland activity.
In a second phase of the study, scientists engineered mice to carry the same mutation. The mice developed excessive sweating just like the human patients, showing a direct correlation between the mutation and the condition. Further studies found that the NaV1.8 channel affects sympathetic nerve cells that control sweating, making those cells more active and causing the body to overproduce sweat.
"We found that this mutation essentially turns up the volume on the nerve signals that stimulate sweating," Brock said. "That insight gives us a specific target to pursue for future therapies."
Who is affected
Hyperhidrosis often runs in families and is most common in adults between 18 and 39. Risk factors include having a close relative with the condition, taking medications that increase sweating, or having an underlying medical condition linked to excessive perspiration.
To diagnose the condition, healthcare providers may order blood or other lab tests to rule out underlying causes, or perform a sweat test to pinpoint where sweating occurs and assess its severity. Standard treatment typically begins with prescription-strength antiperspirant and, depending on severity, can progress to oral medications, botulinum toxin injections, or device therapy.
A new treatment target
Dr Paul Gross, a primary care physician at LIV3 Health, told the Daily Mail that current treatments are designed to control excessive sweating once it is already present. "While these treatments can be quite successful at addressing the symptom of excessive sweating, this approach does not address the biological mechanism as to why some individuals develop hyperhidrosis," he said.
Gross said that by understanding how to treat hyperhidrosis closer to its origin, researchers could direct future therapies toward correcting the abnormal nerve pathways identified in the study. "Although these treatments provide relief from the symptoms experienced by most patients, they do not treat the cause," he said. "Therefore, many people experience the need to have additional treatments throughout their lives."
Gross added that the study could eventually lead to a new generation of treatments targeted at the overactive nerves. "While there is much work to be done before these treatments are available, this study represents an important first step toward providing treatment options that are more accurate and long-term," he said.
