Time to rest a hypothesis? Accumulating evidence that periodic leg movements during sleep are not increased in children with attention deficit hyperactivity disorder (ADHD): results of a case-control study and a meta-analysis.

Abstract

To address the hypothesis that periodic leg movements during sleep (PLMS) are more frequent in children with attention deficit hyperactivity disorder (ADHD) when compared to typically developing (TD) children. To that end we both analyzed PLMS in a recent case-control study and conducted a systematic review and meta-analysis of PLMS frequency in children with ADHD and TD children. In our case-control study we compared PLMS frequency of 24 children with ADHD (mean age 11 years, 17 male) to that of 22 age matched typically developing (TD) children (mean age 10 years, 12 male). A subsequent meta-analysis included 33 studies that described PLMS frequency in groups of children with ADHD and/or groups of TD children. The case-control study did not show any differences in the frequency of PLMS between children with ADHD and TD children, a result that was consistent across a range of different definitions of PLMS, which in turn had a significant and systematic effect on PLMS frequency. The meta-analysis compared the average PLMS indices and the proportion of children with elevated PLMS indices between children with ADHD and TD children and across a number of analyses did not find any meta-analytic results that supported the hypothesis that PLMS are more frequent in children with ADHD. Our results suggest that PLMS are not more frequent in children with ADHD compared to TD children. A finding of frequent PLMS in a child with ADHD should therefore be considered a separate disorder and prompt specific diagnostic and therapeutic strategies.