Daytime dysfunction in children with restless legs syndrome

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Abstract

We investigated daytime dysfunction in children with restless legs syndrome (RLS) and the effects of treatment primarily with iron supplements on RLS symptoms and daytime dysfunction. We recruited 25 children with RLS (male:female = 6:19, mean age at study onset: 12.3 years) for this prospective study, assessing their demographics, symptomatic characteristics, serum ferritin levels, and daytime functioning using the ADHD Rating Scale IV (ADHD-RS-IV), the Pediatric Symptom Checklist (PSC), and the Pediatric Quality of Life Inventory (PedsQL™). Children with RLS were compared with 28 controls (male:female = 10:18, mean age: 13.2 years) on these measures, pre- and post-treatment. Before treatment, ADHD-RS-IV (all ps < 0.05) and PSC scores (p < 0.05) were significantly higher and PedsQL™ scores (all ps < 0.05) significantly lower in the RLS group than in the control group. Eight and one of the RLS group had abnormally high PSC and ADHD-RS-IV scores, respectively. Following treatment, participants' daytime function had improved to levels similar to those of controls. Sixteen out of twenty-three cases were successfully treated primarily with iron supplement. Some children with RLS have daytime dysfunction; however, this can be treated with iron supplements.

Introduction

Restless legs syndrome (RLS) is a sensorimotor disorder characterized by an irresistible urge to move the legs. Following the establishment of the diagnostic criteria for child RLS in a workshop held at the National Institute of Health (NIH) in 2003 [1], a significant number of studies on child RLS have been conducted [2], [3], [4]. The Peds REST study, conducted in the United States (US) and the United Kingdom (UK), revealed that the prevalence of definite RLS was 1.9% in those aged 8 to 11 and 2.0% in those aged 12 to 17 [5]. In a study on children in Turkey, the prevalence of definite RLS was 1.7% in those aged 10 to 12 and 3.2% in those aged 13 to 19 [6]. These study results indicate that RLS is not a rare condition in childhood, despite a relatively lower rate in this age group compared with that in adults [7], [8].

Recent studies have noted that symptoms of attention deficit hyperactivity disorder (ADHD) are frequently complicated by child RLS [5]. Moreover, RLS symptoms have been reported in 12–35% of children with ADHD [9], [10]. These results suggest a possible pathological association between RLS and ADHD [11]. However, neither the type of children with RLS at risk of developing ADHD symptoms nor the severity profile of ADHD symptoms in children with RLS has yet been clarified. Moreover, the impact of RLS on children's daytime dysfunction remains unclear.

Considering these issues, we set out this study to evaluate daytime function in children with RLS using the following previously validated measures: the Japanese version of the ADHD Rating Scale IV (ADHD-RS-IV) to record participants' levels of ADHD symptoms [12], [13]; the Japanese version of the Pediatric Symptom Checklist (PSC), an measurement of psychosocial problems in children [14], [15]; and the Japanese version of the Pediatric Quality of Life Inventory (PedsQL™), version 4, which evaluates quality of life (QOL) in children [16], [17]. We then analyzed the association between the diurnal distribution of RLS symptoms and these daytime function measures and how these scores changed from pre- to post-treatment. In addition, we discussed the effectiveness of iron treatment – which is reportedly effective for treating both RLS and ADHD in patients with low serum ferritin levels [4], [18] – not only on reducing symptoms of child RLS but also reducing the above-indicated daytime dysfunctions.

Section snippets

Methods

This study was approved by the Ethical Committee of the Neuropsychiatric Research Institute, Tokyo, Japan. After receiving a thorough explanation about the purpose and procedure of the present study, all participants and their parents returned written informed consent for participation.

Participants with RLS were 25 children 18 years of age or younger (6 boys, 19 girls; age range: 7–18; mean age: 12.3 years) who visited our outpatient clinic seeking for the treatment of the disorder between

Results

In RLS children the mean age of onset of the symptoms was 8.9 ± 3.1 years old, and the duration of disease morbidity at the time of the survey was 3.4 ± 2.9 years. Six RLS children (24%) had a family history of RLS in their first-degree relatives. The mean serum ferritin level of all the RLS children at the time of diagnosis was 29.7 ± 19.1 ng/mL. Regarding the diurnal distribution of RLS symptoms, 15 RLS children (60%) reported experiencing symptoms both during the day and at night, while 10 RLS

Discussion

In this study, we investigated ADHD scores in children diagnosed with RLS before treatment and the change in the scores following RLS treatment. Moreover, we aimed to identify the impact of RLS in the affected children on other daytime functioning measures. We found that, although their ADHD scores before treatment were significantly higher in comparison with the control group, only one RLS participant showed a pathologically high ADHD-RS-IV score [30], [31]; the other participants scored

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