The study is the work of Dr John W Winkelman, of Harvard Medical School in Boston, Massachusetts, and colleagues, and is published in the Janaury 1st 2008 issue of the journal Neurology.
Winkelman and colleagues also found that people with the most severe and frequent RLS symptoms ran the highest risk of stroke and heart disease.
The largest of its kind, the study included 3,433 community based participants of average age 68 from the Sleep Heart Health Study, a multi-centre cohort study set up by the National Heart Lung and Blood Institute (NHLBI) to discover cardiovascular and other consequences of sleep-disordered breathing.
The researchers used information given by the participants on detailed questionnaires to establish who had RLS and who had received a diagnosis for angina, myocardial infarction, stroke or heart failure from a doctor. Reports of treatments such as coronary revascularization were also included.
This helped the researchers determine the presence of coronary artery disease (CAD) and total cardiovascular disease (CVD), which included CAD and reports of stroke or heart failure.
A diagnosis of RLS was established by four diagnostic criteria, and if symptoms occurred at least five times per month and were associated with at least moderate distress.
The results showed that:
- 6.8 per cent of female and 3.3 per cent of male participants had RLS.
- People with RLS were more than 2 times more likely to have cardiovascular disease or cerebrovascular disease (odds ratio was 2.05 for for CAD and 2.07 for CVD).
- This figure was unchanged after adjusting for age, sex, race, body mass index (BMI), diabetes, high blood pressure, high blood pressure medication, HDL/LDL cholesterol, and smoking status.
- The link between RLS and heart disease and stroke was stronger in people who reported having RLS symptoms at least 16 times per month.
- The link between RLS and heart disease and stroke was also stronger in people who reported severe as opposed to "moderately bothersome" symptoms.
"Restless legs syndrome (RLS) is associated with prevalent coronary artery disease and cardiovascular disease. This association appears stronger in those with greater frequency or severity of RLS symptoms."
Winkelman said although their research did not show that RLS caused cardiovascular and cerebrovascular disease, there was strong evidence to suggest a number of ways in which it may do so.
"In particular, most people with RLS have as many as 200 to 300 periodic leg movements per night of sleep and these leg movements are associated with substantial acute increases in both blood pressure and heart rate, which may, over the long term, produce cardiovascular or cerebrovascular disease," explained Winkelman.
He also said the study was limited by the fact the data was gathered from self-reported questionnaires and not by clinical interview with a trained medical professional.
RLS is a neurological condition where you have the irresistible urge to move your legs, often accompanied by uncomfortable sensations such as creeping, itching pulling, gnawing and tugging. The symptoms often get worse when you rest, for instance when you lie down, and get better when you move your legs.
One of the biggest complaints of RLS sufferers is difficulty falling and staying asleep. Also, many RLS sufferers have periodic limb movements of sleep (PLMS), where the legs jerk every 20 or 30 seconds, on and off all night during sleep. This causes sleep deprivation that can seriously impact health, relationships, work, and general quality of life.
According to the RLS Foundation, up to 10 per cent of Americans have the syndrome.
"Association of restless legs syndrome and cardiovascular disease in the Sleep Heart Health Study."
Winkelman, John W., Shahar, Eyal, Sharief, Imran, Gottlieb, Daniel J.
Neurology 2008 70: 35-42
Published online 1st January 2008.
Click here for Abstract.
Click here for more information on RLS (the RLS Foundation, US).
Sources: journal article, American Academy of Neurology press release, Sleep Heart Health Study website, RLS Foundation.
Written by: Catharine Paddock