(Agencies)
Updated: 2008-01-03 22:25

Earlier studies showed an association between restless legs syndrome and cardiovascular disease, but the studies had limitations. RLS has also suffered from a public image problem, which may explain why so few studies have explored the condition.

"RLS has borne the brunt of a lot of skepticism," Rye explained. "Snoring started out the same way... It took decades to convince primary-care physicians that we have to treat sleep apnea, that it's not just a nuisance that dad snores. It [sleep apnea] has a huge added risk for obesity and stroke and hypertension and cardiovascular disease."

The new study, the largest of its kind, looked at 3,433 men and women, with an average age of 68, who were enrolled in the Sleep Heart Health Study, which was originally designed to look at the cardiovascular consequences of sleep-disordered breathing.

A diagnosis of restless legs syndrome was based on a questionnaire completed by all study participants. The participants also answered questions about cardiovascular disease and stroke. Almost 7 percent of women and 3.3 percent of men in the study had restless legs syndrome.

People with the syndrome were more than twice as likely to have cardiovascular disease or stroke. The association was strongest among those who had RLS symptoms a minimum of 16 times a month and among those who said their symptoms were severe.

The study can't prove a cause-and-effect relationship, but such a link could make physiological sense. Most people with restless legs syndrome have up to 300 periodic leg movements a night, and those movements are associated with increases in blood pressure and heart rate, the study authors said.

Also, people with RLS often also suffer from sleep deprivation, which has been associated with cardiovascular disease.

"The direct data would suggest that the disrupted sleep and arousals that occur with RLS are really what's contributing to hypertension and heightened autonomic nervous system activity, which in turns leads to cardiovascular [problems]," Rye said. "But this [study] can't answer that kind of question."

The next study should look to see if treatments for restless legs syndrome reduce the risk for heart disease and stroke, Rye added. "Nobody has done that, because nobody has recognized that there was a problem," he said.

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