Associations between symptoms of inattention, hyperactivity, restless legs, and periodic leg movements

Study Objectives: Attention-deficit/hyperactivity disorder (ADHD) has shown associations with restless legs syndrome (RLS) and periodic leg movements during sleep (PLMS) among small samples of referred children, but whether RLS or PLMS are common more generally among hyperactive children has not been well studied. Design: Cross-sectional survey, Setting: Two university-affiliated but community-based general pediatrics clinics. Patients: N=866 children (469 boys), aged 2.0 to 13.9 years (mean 6.8+/-3.2 years), with clinic appointments. Interventions: N/A Measurements. A validated Pediatric Sleep Questionnaire assessed for PLMS (a 6-item subscale), restless legs, growing pains, and several potential confounds of an association between behavior and PLMS or RLS. Parents also completed two common behavioral measures, a DSM-IV-derived inattention/hyperactivity scale (IHS) and the hyperactivity index (HI, expressed as a t-score) of the Conners' Parent Rating Scale. Results; Restless legs were reported in 17% (95% C.I. [15, 20]) of the subjects. Positive HI scores (>60) were found in 13% [11, 16] of all subjects, 18% [12, 25] of children with restless legs, and 11% [9, 14] of children without restless legs (chi-square p<0.05). Odds ratios between HI>60 and each of the following were: a one-s.d. increase in the overall PLMS score, 1.6 [1.4, 1.9]; restless legs, 1.9 [1.1, 3,2]; and growing pains, 1.9 [0.9, 3.6] (all age and sex-adjusted). Results were similar for high IHS scores (>1.25). The associations between each behavioral measure and the PLMS score retained significance after statistical adjustment for sleepiness, snoring, restless sleep in general, or stimulant use. Conclusions: Inattention and hyperactivity among general pediatric patients are associated with symptoms of PLMS and RLS. If either condition contributes to hyperactivity, the magnitude of association suggests an important public health problem.