Originally published in MedPage Today
by Charles Bankhead, MedPage Today Staff Writer
Men with restless leg syndrome (RLS) had a significantly increased risk of erectile dysfunction compared with men who did not have the neurologic disorder, data from a large cohort study showed.
The likelihood of erectile dysfunction increased with the frequency of restless leg episodes, reaching an adjusted risk apex about 80% greater for men with the most frequent episodes of RLS compared with men who did not have the syndrome, according a report in the January issue of Sleep.
The findings suggest a common etiology for restless leg syndrome and erectile dysfunction and support preclinical evidence of altered neurotransmitter receptors linking the two conditions.
“This finding indirectly supports a role of dopamine in restless leg syndrome,” Xiang Gao, MD, PhD, of Brigham and Women’s Hospital and Harvard, and colleagues wrote. “Further epidemiologic studies are warranted to clarify the temporal relationships between restless leg syndrome and erectile dysfunction and to explore the biological mechanisms underlying this association.”
Although the etiology of RLS remains unclear, dopaminergic hypofunction in the central nervous system (CNS) has been implicated in the condition’s pathophysiology. The dopamine hypothesis has been supported by studies showing that RLS symptoms improve with administration of L-dopa or a dopamine agonist and worsen with administration of dopamine antagonists that cross the blood-brain barrier, the authors wrote.
Dopamine may also play a role in erectile function. For example, Gao and colleagues previously reported an association between erectile dysfunction and Parkinson’s disease, another condition involving dopamine hypofunction in the CNS (Am J Epidemiol 2007; 166: 1446-50).
To continue the exploration of the dopamine hypothesis, investigators analyzed data from the ongoing Health Professional Follow-up Study to determine whether men with RLS have an increased prevalence of erectile dysfunction. The analysis included 23,119 men who responded to questions about restless leg syndrome in a 2002 follow-up survey.
The study group comprised 22,175 men with no history of RLS, 549 who reported five to 14 episodes of RLS symptoms per month, and 395 who reported 15 or more episodes a month.
As compared with men without RLS, those with the condition were older, more likely to be smokers, less likely to exercise, and more likely to take antidepressants. They also had a higher BMI and anxiety score and greater prevalence of stroke and hypertension.
Overall, 52.9% of men with RLS had erectile dysfunction compared with 40.3% of men without the condition (OR 1.47, 95% CI 1.3 to 1.7).
Men who reported five to 14 episodes of RLS symptoms monthly had an adjusted odds ratio of 1.16 for erectile dysfunction compared with men who did not have the condition. More frequent episodes of RLS symptoms were associated with an odds ratio of 1.78 for erectile dysfunction (P<0.0001 for trend).
In a model adjusted only for age, the odds ratio for erectile dysfunction was 1.22 among men who reported five to 14 symptomatic episodes monthly and 1.93 among men with more frequent episodes of RLS symptoms (P<0.0001 versus men without symptoms). Adjustment for other variables did not appreciably change the results, the authors reported.
“We did not find significant interaction between presence of restless leg syndrome and age, obesity, and smoking status, in relation to the likelihood of having erectile dysfunction,” they wrote. “Further, the interactions between presence of restless leg syndrome and antidepressant use were also not significant.”
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