Symptoms of Attention-Deficit/Hyperactivity Disorder (ADHD) in Adults With Restless Legs Syndrome
From SLEEP. December 15, 2004 (Volume 27, Number 8). Wagner ML, Walters AS, Fisher BC
Overview The prevalence of attention-deficit/hyperactivity disorder (ADHD) is 3% to 10% in children.[1]
Children complain of a variety of symptoms related to restlessness and an inability to pay attention. ADHD symptoms may persist into adulthood in about two thirds of patients.[2]
ADHD symptoms may be increased by sleep disruption, and children with ADHD demonstrate objective daytime somnolence. Therefore, the presence of primary sleep disorders, especially sleep-disordered breathing and periodic limb movement disorder, should be investigated in children with ADHD.[3]
Objective In this study, Wagner and associates looked for the occurrence of ADHD symptoms in adults with restless legs syndrome (RLS), normal controls, and controls with insomnia.
Methodology The investigators prospectively studied sequential adult patients with RLS (n = 62), insomnia (n = 32), and adult controls (n = 77). They used the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition ADHD criteria; the Brown Attention-Deficit Disorder (ADD) Scale for adults; a structured psychological interview; and the Restless Legs Syndrome Study Group Rating Scale to diagnose and to assess syndrome severity.
Results Investigators found that 26% of the RLS patients had ADHD symptoms vs 6% of insomnia patients and 5% of control patients. Furthermore, the mean Brown ADD score was greater in RLS patients (37 ± 28) than in patients with insomnia (24 ± 18) or controls (21 ± 18). In addition, the RLS symptom severity (0-40) was greater in RLS patients with ADD (26 ± 9) symptoms than in those without ADD (21 ± 10) symptoms.
Conclusion ADHD symptoms are more common in RLS patients than in patients with insomnia or controls.
Discussion This is the first study to evaluate the prevalence of ADHD symptoms in adults with RLS. The results of this study suggest an interaction between the symptoms of ADHD and RLS, and adds to the growing body of evidence suggesting a relationship between the presence of sleep disorders and symptoms of inattention and hyperactivity.
Review An association between ADHD and RLS has been demonstrated. Patients with RLS often suffer from insomnia because of their leg discomfort. Some children diagnosed with growing pains meet the diagnostic criteria for RLS, and a family history of RLS is common in these children.[4]
Children with RLS often cannot sit still at their school desks because they need to get up and walk around to get rid of their leg discomfort. The majority of patients with RLS experience periodic limb movements of sleep (PLMS). Sleep disruption from arousals due to PLMS could also contribute to the inattention and hyperactivity seen in patients with ADHD.[5]
The syndromes of ADHD and RLS/PLMS are linked by evidence that both disorders involve a dopaminergic dysfunction or imbalance. The results of positron emission tomographic scans have demonstrated reductions in dopaminergic function in the midbrain as well as frontal and prefrontal regions of the brain in patients with ADHD.[6]
The results from positron emission tomographic scans and cerebrospinal fluid studies, as well as multiple therapeutic studies with dopaminergic agents in RLS, suggest that RLS may result from a deficiency of dopamine.[7]
Results from controlled clinical studies have demonstrated that children with ADHD have a greater prevalence of PLMS and RLS than do control children, and parents of children with ADHD are more likely to have RLS/PLMS than are control parents.[8]
Furthermore, children with RLS have a higher prevalence of ADHD, and up to 44% of children with PLMS may have ADHD.[9,10]
In a small group of patients with ADHD and RLS/PLMS, treatment of RLS/PLMS with dopaminergic agents resulted in an amelioration of ADHD.[11]
Clinical Pearl Patients with RLS should be screened for ADHD symptoms, and those with ADHD should be screened for RLS symptoms. Evaluation and treatment for RLS/PLMS should be considered before starting treatment for ADHD.
This program was supported by an independent educational grant from GlaxoSmithKline.
