The study, which was funded by the National Institutes of Health, followed more than 11,000 men who were free of erectile dysfunction (ED), diabetes, and arthritis when they were enrolled in 2002. The average age of study participants was 64.
Over six years of follow-up, about 2,000 men in the study developed ED.
Even after ruling out the effects of factors known to increase the risk of erectile dysfunction, like age, smoking, obesity, antidepressant medications, and snoring, researchers found that men who had at least five episodes of restless legs syndrome each month were about 50% more likely to develop ED than men who had no symptoms of the problem.
Men with more frequent symptoms were at even higher risk.
Men who experienced more than 14 episodes of restless legs syndrome each month had a 66% greater risk of developing ED than men without the condition.
A Link to Low Dopamine Levels
Restless legs syndrome is a poorly understood neurological disorder that affects up to 15% of all adults. It is characterized by unpleasant sensations like pulling or creeping that often strike at night, when muscles are relaxed. These sensations typically compel sufferers to move to relieve their discomfort.
A previous study, published in 2010 by the same team, found a strong relationship between restless legs syndrome and ED in a large sample of older men.
But because that study just looked a snapshot in time, investigators couldn’t be sure which problem came first, something that could hint at how they are related.
Study researcher Xiang Gao, MD, PhD, assistant professor of medicine at Harvard University and an associate epidemiologist at Brigham and Women’s Hospital in Boston, says he thinks that low dopamine levels may be to blame for both conditions.