Study Links Restless Legs Syndrome with Erectile Dysfunction

A new study found that men who experience RLS 15 or more times a month also experience a 2x higher incidence of erectile dysfunction.

"These results are not surprising — they are pretty consistent with our hypothesis — but more study is needed to explore the exact mechanism behind this association," said lead author Xiang Gao, MD, PhD, instructor of medicine at Harvard Medical School, associate epidemiologist at Brigham and Women's Hospital, and research scientist at the Harvard School of Public Health in Boston, Massachusetts.

The relationship between ED and RLS was thought to be partly due to dopamine function and sleep disorders, as both conditions are associated with these.

Study participants consisted of 23 thousand US men who worked in various forms of health profession ranging in age from 40 to 75. All were free of diabetes and arthritis. A little over 4% of the men reported experiencing RLS at least five times per month. RLS negatively impacts sleep quality, as the uncomfortable feelings it creates in legs result in an urge to move them — and the condition worsens at night. RLS affects 5-15% of the adult US population.

Study data was obtained by way of questionnaires that the participants completed every two years starting in 1986. The questionnaires included gathering information about potential confounders, such as age, smoking habits, weight and medical history.

On the 2000 and 2004 questionnaires, study participants rated their ability to maintain an erection as being very poor, poor, fair, good, or very good. Ratings of poor or very poor were considered to be ED.

Results

The data (evaluated through 2004) revealed that 52.9% of men with RLS experienced ED, compared to only 40.3% of men without RLS. Those who reported more frequent RLS symptoms also reported a higher incidence ED.

"The frequency of symptoms is a marker of severity, so this means that men with more severe RS are more likely to have ED; that's a dose-response association," said Dr. Gao.

Possible Explanations

Dr. Gao suggested several possible mechanisms that might explain the association between RLS and ED. Hypofunction of dopamine in the central nervous system is associated with both conditions and could at least partly explain the association. Current therapies for RLS include dopamine-based approaches, and experimental studies show that dopamine-related drugs may be effective for ED too, although more study is needed to confirm this.

The association could also be a result of sleep apnea or other sleep disorders that may affect hormonal, neural, and endothelial physiology. There could also be a genetic contribution — people with a specific mutated gene that affects spinal cord development have a higher risk for RLS, added Dr. Gao.

The presence of other chronic conditions, such as cardiovascular disease, could play a role, although the study controlled for these variables.

Because the study was cross-sectional, it is not possible to determine whether RLS is causing ED or the other way around. Dr. Gao emphasized that since this is the first, and therefore the only, study to look at the relationship between RLS and ED, more studies, especially prospective ones, are needed before any therapy implications will become clear. "If a prospective study shows RLS could be a marker for the developing of ED in the future, then maybe addressing RLS could be a benefit for ED, but at this time we can say nothing," said Dr. Gao.

References

Sleep. 2009;33:75-79.

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