Restless legs syndrome as a possible predictor for psychiatric disorders in parents of children with ADHD.

Attention-deficit hyperactivity disorder (ADHD) is a common disorder with estimated prevalence of 5% in children and 3.4% in adults. Psychiatric disorders are a frequent concomitant feature. Restless legs syndrome (RLS) may mimic the symptoms of ADHD. The aim of the study is to evaluate whether the presence of RLS predicts occurrence of psychiatric disorders in parents of children with ADHD. Thirty-seven parents of 26 children with ADHD were examined for RLS and for lifetime prevalence rates of psychiatric disorders and personality disorders based on the Structured Clinical Interview for DSM-IV Diagnoses (SCID). Prevalence rates in parents were 29.7% for RLS, 67.6% for Axis I and 40.5% for Axis II disorders. Mothers revealed higher rates for depression, anxiety disorders and ADHD than fathers, whereas personality disorders occurred at higher rates in fathers. The presence of RLS predicted a diagnosis of ADHD (odds ratio (OR) 21.9), agoraphobia (OR = 20.4) and any anxiety disorder (OR = 8.5). Although limited by the small sample size, we found evidence for increased rates of cluster B personality disorders (OR = 59.3) in parents with RLS. All parents of the latter group (100%) reported a positive family history of psychiatric disorders which was not the case in parents without RLS (69.2%) excluding the index children with ADHD. RLS seems to indicate increased vulnerability for psychiatric disorders, i.e., ADHD and anxiety disorders, in a subgroup of parents from ADHD children. Synaptic dysfunction affecting dopaminergic transmission among other transmitter systems may be a common final pathway related to the phenotypic spectrum of ADHD.