Endophenotypes of ADHD: A Study of the Relationship between ADHD and Enuresis

ADHD is one of the most common childhood psychiatric disorders and despite that fact this it has been heavily researched over the years, there is no consensus on the etiology of the disorder.  Endophenotype research is a relatively new approach that has been utilized to help identify more etiologically pure phenotypes of complex psychiatric disorders.  This study is one of the first to examine enuresis as a potential endophenotype of ADHD.  This study examined the pattern of cortical arousal in children with ADHD and comorbid enuresis to explore if the cortical hypoarousal seen at night in children with enuresis is also present during the day in children with these comorbid conditions.  Specifically this study hoped to ascertain if any daytime indicators of inattention or behavioral inhibition were associated with a risk for enuresis .  Quantitative electroencephalographic (QEEG) data was collected for 449 subjects.  The QEEG data was analyzed looking at the absolute and relative values for theta, beta, and sensorimotor rhythm (smr) waves. As predicted, the presence of enuresis was significantly higher in a population of children with ADHD as compared to the prevalence found in the general population.  This finding lends support to the likelihood of enuresis as an endophenotype for ADHD.  Contrary to prediction, no significant differences were found between children with ADHD and current enuresis as compared to children with ADHD and no enuresis; however, differences in QEEG data were found between children with ADHD only and those with ADHD and a past history of enuresis. The results are discussed in terms of their implications for future research.