To determine the occurrence of symptoms of attention-deficit/hyperactivity disorder (ADHD) in adults with restless legs syndrome (RLS), normal controls, and controls with insomnia.
The occurrence and severity of current ADHD symptoms were determined in a prospective study of sequential adult patients with RLS (n = 62) or insomnia (n = 32) and adult controls (n = 77) using Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) ADHD criteria, the Brown Attention-Deficit Disorder (ADD) Scale for adults, and a structured psychological interview. RLS severity was assessed using the International RLS Study Group Rating Scale (IRLS).
Only 1 experimental subject had previously been diagnosed with ADHD. More RLS patients (26%) than insomnia patients (6%) or controls (5%) had ADHD symptoms using age-adjusted total DSM-IV ADHD scores (P < .01). The mean Brown ADD score was greater in RLS patients (37 +/- 28) than in patients with insomnia (24 +/- 18) or controls (21 +/- 18) (P < .01). The RLS symptom severity (0-40 scale) was greater in RLS patients with ADD symptoms (26 +/- 9) than in those without ADD (21 +/- 10) (P < .04). Of the subjects with a Brown ADD score > 40, all reported ADD symptoms in 2 settings, and the majority had had ADHD symptoms since childhood. For subjects with a Brown ADD score > 40, there were no differences between the RLS, insomnia control, and normal control groups in quality of life or the level of anxiety or depression.
ADHD symptoms are more common in RLS patients than in patients with insomnia or controls. RLS leg discomfort or poor quality of sleep may theoretically lead to hyperactivity and lack of concentration. Alternatively, RLS and ADHD may be part of a single symptom complex, and dopaminergic deficiency may play a role in both disorders.