There's evidence suggesting that gluten sensitivity may be at the root of many neurological and psychiatric conditions, including attention deficit hyperactivity disorder (ADHD). http://articles.mercola.com/sites/articles/archive/2011/11/02/gluten-contribute-to-adhd.aspx?e_cid=20111102_DNL_art_2
A variety of behavioral problems are linked to problems in your gut, not only from gluten, WGA and other components of grains but also due to the gut-brain connection.
The gut-brain connection is well recognized as a basic tenet of physiology and medicine, so this isn't all that surprising, even though it's often overlooked.
There's also a wealth of evidence showing gastrointestinal involvement in a variety of neurological diseases.