Childhood restless legs syndrome: A longitudinal study of prevalence and familial aggregation.

Restless legs syndrome is a relatively common neurological disorder in adults. In childhood, however, its prevalence and genetic contribution are still largely unknown. The objectives of this study were to assess the prevalence of restless legs syndrome (RLS) during childhood and adolescence in a large population-based cohort and evaluate the degree of association with parental history. Data from a large, prospective longitudinal cohort from the Quebec Longitudinal Study of Child Development of 1,856 children born in 1997-1998 were studied from 2005 to 2013. The prevalence of RLS was assessed at ages 7, 8, 12, 13 and 15 years through a questionnaire completed by the mother. Parental history of RLS was also queried. Between 7 and 15 years of age, the yearly prevalence of RLS ranged from 2.4% to 3.1%, with a higher prevalence in boys than girls at 12 years old. The prevalence of RLS at any time during this period was 8.6% but only 1.8% of parents answered positively at least twice during the longitudinal study. This low persistent rate could be explained by remissions or the use of parental report. The prevalence was higher when there was at least one parent affected with RLS (13.0%) compared to children without a parental history (6.9%). Findings from this population-based study confirm the high prevalence of RLS in children aged 7-15 years and corroborate the strong familial aggregation for RLS. Parents should be encouraged to inform the paediatrician about the presence of RLS in the family to help the diagnostic process.