Original Article
Impact of restless legs syndrome and iron deficiency
on attention-deficit/hyperactivity disorder in children
Eric Konofal
a,b,c,
*
, Samuele Cortese
a
, Martine Marchand
d
, Marie-Christine Mouren
a
,
Isabelle Arnulf
b
, Michel Lecendreux
a,c
a
Service de Psychopathologie de l’Enfant et de l’Adolescent, Ho
ˆ
pital Robert Debre
´
, 48 boulevard Se
´
rurier, 75019 Paris,
Assistance Publique – Ho
ˆ
pitaux de Paris, France
b
Fe
´
de
´
ration des Pathologies du Sommeil Groupe Hospitalier Pitie
´
-Salpe
ˆ
trie
`
re, 47-83 boulevard de I’Ho
ˆ
pital, 75013 Paris Cedex,
Assistance Publique – Ho
ˆ
pitaux de Paris, France
c
Centre Pe
´
diatrique des Pathologies du Sommeil, Ho
ˆ
pital Robert Debre
´
, 48 boulevard Se
´
rurier, 75019 Paris,
Assistance Publique – Ho
ˆ
pitaux de Paris, France
d
Service de Biochimie, Ho
ˆ
pital Robert Debre
´
, 48 boulevard Se
´
rurier, 75019 Paris, Assistance Publique – Ho
ˆ
pitaux de Paris, France
Received 25 February 2007; received in revised form 10 April 2007; accepted 24 April 2007
Available online 20 July 2007
Abstract
Objective: Increasing evidence suggests a significant comorbidity between attention-deficit/hyperactivity disorder (ADHD) and rest-
less legs syndrome (RLS). Iron deficiency may underlie common pathophysiological mechanisms in subjects with ADHD plus RLS
(ADHD+RLS). To date, the impact of iron deficiency, RLS and familial history of RLS on ADHD severity has been scarcely exam-
ined in children. These issues are addressed in the present study.
Methods: Serum ferritin levels, familial history of RLS (diagnosed using National Institutes of Health (NIH) criteria) and previous
iron supplementation in infancy were assessed in 12 ADHD+RLS children, 10 ADHD children and 10 controls. RLS was diagnosed
using NIH-specific pediatric criteria, and ADHD severity was assessed using the Conners’ Parent Rating scale.
Results: ADHD symptom severity was higher, although not significantly, in children with ADHD+RLS compared to ADHD. The
mean serum ferritin levels were significantly lower in children with ADHD than in the control group (p<0.0005). There was a trend
for lower ferritin levels in ADHD+RLS subjects versus ADHD. Both a positive family history of RLS and previous iron supple-
mentation in infancy were associated with more severe ADHD scores.
Conclusions: Children with ADHD and a positive family history of RLS appear to represent a subgroup particularly at risk for
severe ADHD symptoms. Iron deficiency may contribute to the severity of symptoms. We suggest that clinicians consider assessing
children with ADHD for RLS, a family history of RLS, and iron deficiency.
Ó 2007 Elsevier B.V. All rights reserved.
Keywords: Restless legs syndrome; Attention-deficit/hyperactivity disorder; Iron; Dopamine; Ferritin
1. Introduction
Restless legs syndrome (RLS) is a sensorimotor disor-
der estimated to affect approximately 5–10% of the gen-
eral population in Western Europe and the United States
[1,2]. In adults, RLS is characterized by uncomfortable
leg sensations with an irresistible urge to move the legs
[3]. These leg sensations are worse when sitting or lying
and at night and are relieved, at least partially, by move-
ment [3]. Children may exhibit and report symptoms of
RLS differently from adults, due to their limited ability
to describe the subjective symptomatology of RLS [4].
1389-9457/$ - see front matter Ó 2007 Elsevier B.V. All rights reserved.
doi:10.1016/j.sleep.2007.04.022
*
Corresponding author. Tel.: +33 140032263; fax: +33 140032297.
E-mail address: eric.konofal@rdb.aphp.fr (E. Konofal).
www.elsevier.com/locate/sleep
Sleep Medicine 8 (2007) 711–715