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People with restless legs syndrome, or RLS, are twice as likely as those without it to suffer a stroke or heart disease, according to research.
The risk is greatest in those with the most frequent and severe symptoms, says an American study published in the Neurology science journal.
Restless legs syndrome is a neurological condition characterised by an irresistible urge to move the legs. Sufferers say it often hits at night, preventing them from sleeping.
"It feels like something crawling inside your legs, biting on you," said Betty Shaw, a 68-year-old florist in Covington, Georgia, who was diagnosed with it. So was her 43-year-old daughter.
This is not the first study to link RLS with cardiovascular disease, the study team notes in the January 1 issue of the journal Neurology. However, two prior studies that supported an association did not use current RLS diagnostic criteria and one of them included only men.
In the current study, "association of RLS with heart disease and stroke was strongest in those people who had RLS symptoms at least 16 times per month", study chief Dr John Winkelman, from Harvard Medical School in Boston, said. "There was also an increased risk among people who said their RLS symptoms were severe compared to those with less bothersome symptoms."
The findings stem from an analysis of data for 1559 men and 1874 women enrolled in the Sleep Heart Health Study, a community-based study that looked at the impact of sleep-disordered breathing on cardiovascular health. The average patient age was 67.9 years.
Overall, 6.8 per cent of women and 3.3 per cent of men had RLS.
Analyses showed that people with RLS had a greater than two-fold higher risk of suffering cardiovascular disease or stroke. The results remained the same after adjusting for age, sex, race, body weight, diabetes, high blood pressure, high blood pressure medication, cholesterol levels, and smoking.
"RLS could increase cardiovascular risk by a number of potential mechanisms," the investigators note - for example, by raising night-time heart rate and blood pressure. Alternatively, cardiovascular disease could cause RLS.
Further studies are needed to better understand the association between RLS and cardiovascular disease, the researchers conclude.
In earlier research, other scientists linked certain genes to restless legs syndrome.
Scientists found a certain variation in the human genome that, they say, probably accounts for 50 per cent of restless legs cases. They also found that the variation was associated with lower iron levels, echoing but not explaining a relationship noted in earlier research.
Research published in the New England Journal study indicated as many as 65 per cent of adults carry the gene variation that can lead to symptoms.
The syndrome is diagnosed through symptoms such as periodic limb movements in sleep, but lots of people may have limb movements without having the condition.
- REUTERS
