Attention Deficit Disorder

[Akira]

Hello. I am curious about the neurophysiological or neurochemical 
causation of ADD. I realize that the medical community has been rather 
unsuccessful at discovering a definitive cause for the disorder, but 
being an undergrad, I am not familiar with the different explanations. If 
someone is knowledgeable in this specific disorder could you provide me 
with information or refer me to some documents.