New research suggests that 23 percent of people have restless leg syndrome, or RLS, which is much higher than previously reported rates of 3 percent to 10 percent.

RLS causes unpleasant sensations in the legs when a person is at rest, triggering an uncontrollable urge to move the legs to get relief. The cause is unknown, but researchers suspect that an imbalance in the movement-regulating brain chemical dopamine plays a role. Drugs that increase dopamine activity are sometimes used to treat RLS.

The new research, which was presented this week at a medical conference in San Diego, California, suggests that, overall, non-African-Americans experience RLS four times more often than African-Americans.

Furthermore, 2 out of 5 Caucasian women were found to have RLS, nearly four times the incidence of RLS in African-American women and the highest incidence among all groups.

“Some risk factors for restless legs syndrome appear to be more common among

women,” co-researcher Dr. Ammar Alkhazna, from the University of Missouri, Kansas City, noted in a statement from the meeting. “Women are more likely to be iron deficient than men and have rheumatoid arthritis, which are known risk factors for RLS.”

The findings stem from a study of 190 patients who were selected during visits to a primary care clinic and were evaluated for RLS.

One hundred three of the participants were African American and 87 were non-African-American, with Caucasians the majority. In both ethnic groups, roughly 60 percent were female. The average ages of the African American and non-African-American groups were 53 and 50 years, respectively.

In non-African Americans, the RLS diagnosis was definite in 36 percent and negative in 64 percent. In African Americans, the diagnosis was definite in 12 percent, probable in 4 percent, negative in 83 percent, and uncertain in 1 percent.

“This is the first study to show such a striking difference in RLS prevalence across racial groups,” Alkhazna told Reuters Health. “This likely reflects a combination of factors, including a genetic predisposition to RLS, diet - including iron intake - medications, and possibly culture.”

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By Anthony J. Brown, MD

NEW YORK (Reuters Health)