at least initially, with dopaminergic treatment. 
Prevalence 
Prevalence rates of RLS vary widely when br oad criteria are utilized but range from 2% to
7.2% when more defined criteria are employed . When frequency of symptoms is at least
three times per week with moderate or severe distress, the prevalence rate is 1.6%; when
frequency of symptoms is a minimum of one ti me per week, the prevalence rate is 4.5%.
Females are 1.5–2 times more likely than males to have RLS. RLS also increases with age.
The prevalence of RLS may be lower in Asian populations. 
Development and Course
The onset of RLS typically occurs in the seco nd or third decade. Approximately 40% of in-
dividuals diagnosed with RLS during adul thood report having experienced symptoms
before age 20 years, and 20% report having experienced symptoms before age 10 years.
Prevalence rates of RLS increase steadily with age until about age 60 years, with symptoms
remaining stable or decreasing slightly in older age groups. Compared with nonfamilial
cases, familial RLS usually has a younger age at  onset and a slower pr ogressive course. The
clinical course of RLS differs by age at onset.  When onset occurs before age 45, there is of-
ten a slow progression of symptoms. In late-onset RLS, rapid progression is typical, and
aggravating factors are common. Symptoms of RLS appear similar acro ss the lifespan, re-
maining stable or decreasing slightly in older age groups.
Diagnosis of RLS in children can be diff icult because of the self-report component.
While Criterion A for adults assumes that the description of “urge to move” is by the pa-