 - Attention deficit hyperactivity disorder ADHD is one of the most common and inheritable of all neuropsychiatric disorders. It causes problems with attention and impulse control. However, the genetic component of ADHD has not been fully studied, including how genes interact with the environment. Researchers want to study children and adults who have ADHD. They will look at how genetic, brain structure, and environmental factors affect ADHD in children and adults. 