READING last week鈥檚 newspapers, you could be forgiven for thinking that companies criticised for their marketing of drugs for restless legs syndrome (RLS) have been well and truly vindicated. 鈥溞影稍磗 have identified a gene variant that makes those who carry it 70 to 80 per cent more likely to suffer from RLS,鈥� The Daily Telegraph in London reported on 19 July, for example. 鈥淪ome experts have argued that RLS does not really exist and was invented by drugs manufacturers.鈥� It then quoted study leader David Rye, a neurologist at Emory University in Atlanta, Georgia: 鈥淲e now have concrete evidence that RLS is an authentic disorder.鈥�
Look more closely at the science, and this story is not all it seems. Rye鈥檚 team has not discovered a gene for RLS. And the serious critics do not deny the disease exists 鈥� they are concerned that pharmaceutical companies鈥� aggressive marketing will cause drugs to be prescribed to people with symptoms too mild to warrant them. Far from demolishing this concern, the latest buzz about RLS is set to make that more likely.
RLS does make life miserable for those with severe symptoms, which include sensations that impel them to move their legs, especially at night. About 80 per cent of people with RLS also experience a related condition called 鈥減eriodic limb movements in sleep鈥� or PLMS. This is what Rye and his colleagues at the Icelandic company deCode Genetics studied. They found that a common variant of a gene called BTBD9 was associated with PLMS in RLS patients ().
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But many people who have PLMS don鈥檛 have RLS, and the gene association was strongest in them. By contrast, there was no association between the gene and RLS in those who did not have PLMS. Rye and his colleagues have found a gene for PLMS, not RLS.
A paper published by a second team last week in Nature Genetics () describes three gene variants associated with RLS, one of which was the BTBD9 variant described in the first paper. As this study didn鈥檛 consider the overlap with PLMS, the other two might also be genes for PLMS rather than RLS.
Both papers present their findings in the context of RLS, and it is easy to see from their wording how reporters skimming them might conclude that a gene for the condition had been found. Rye鈥檚 paper also contributes to the idea that the findings demolish criticisms of drug marketing. It states that 鈥渢he authenticity of RLS has recently been questioned鈥�, citing a paper by Steven Woloshin and Lisa Schwartz of Dartmouth Medical School in New Hampshire (PLoS Medicine, ). Yet Woloshin and Schwartz do not deny the existence of RLS. Their paper actually questions estimates of its prevalence promoted by GlaxoSmithKline (GSK), which makes the RLS drug Requip.
鈥淚t is easy to see from the papers how reporters concluded that a gene for restless leg syndrome had been found鈥�
Some of the news articles describing Rye鈥檚 findings repeat GSK鈥檚 mantra that 10 per cent of US adults suffer from the condition 鈥� despite a study suggesting that only 2.7 per cent of adults have symptoms severe enough for treatment to be considered (). Woloshin and Schwartz鈥檚 concern is that drug marketing will encourage large numbers of people with discomfort in their legs to pressure their doctors into prescribing drugs they don鈥檛 need. In the US, GSK spent $27 million on TV ads for Requip in 2005. TV and print ads for Boehringer Ingelheim鈥檚 drug Mirapex began running two days before Rye鈥檚 paper appeared.
Both drugs were originally developed to treat Parkinson鈥檚 disease. They stimulate receptors for the neurotransmitter dopamine, and can have wide-ranging side effects. Few of the news articles covering Rye鈥檚 findings mention the risks of drug treatment, or note that he is a paid consultant to both GSK and Boehringer Ingelheim. But those sins of omission pale beside the comments of CNN medical producer Amy Burkholder, who on the TV network鈥檚 health blog stated that RLS 鈥渕ay affect many more of us than we think: as many as 65 per cent of adults carry the gene variation that can lead to symptoms鈥�.
True, many of us carry the 鈥渞isky鈥� variant of BTBD9. But that does not mean that we have RLS, and says nothing about the need for drug treatment. Journalists should be careful not to do drug companies鈥� marketing for them.
