http://casemed.case.edu/cwrumed360/news-releases/release.cfm?news_id=1149&news_category=8
“People with attention deficits have difficulty focusing and often display compulsive behavior. The new study suggests these symptoms could be due to dysfunction in a gene—ErbB4—that helps different brain regions communicate. The gene is a known risk factor for psychiatric disorders, and is required to maintain healthy neurotransmitter levels in the brain.”