Risk Factors
Restless legs syndrome is estimated to affect between 2.5% and 15% of the general population. It is more common in women than in men, and its prevalence increases with age. An estimated 10% to 28% of those older than 65 are affected by the disorder.In about 40% of patients, RLS begins in adolescence, though it is uncommon in young children.
Family History
Up to two thirds of people with RLS have a family history of the disorder. In such cases, it is more likely to occur before age 40. (A family history of RLS is less likely in people who develop it as older adults.) It is also more common in populations from northern and western Europe, giving added support for a genetic basis for some cases of the disorder.
Attention Deficit Activity Disorder (ADHD)
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RLS and periodic limb movement disorder in children are strongly associated with inattention and hyperactivity. One study suggested that a quarter of children diagnosed with attention-deficit hyperactivity disorder (ADHD) also has RLS or PLMD, and this may actually contribute to inattentiveness and hyperactivity. The disorders have much in common, including poor sleep habits, twitching, and the need to get up suddenly and walk about frequently. A 2001 study also reported an associated between adult attention deficit disorder and RLS. More research is needed to determine if RLS is a cause of some cases of ADHD or if it simply aggravates it. Some evidence suggests that the link between the diseases may be a deficiency in the brain chemical dopamine, which has been observed in both conditions.
Pregnancy
About 20% of pregnant women report RLS, which in most cases goes away after delivery. RLS in this population has been strongly associated with deficiencies in iron and with B vitamin folate (which in turn reduce iron levels). Symptoms typically disappear within a month after delivery.
Dialysis
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