I copied this from a website on preparing for a neuropsychologist evaluation.
If your child takes stimulant medication for ADHD or ADD, s/he may or may not be asked to take it the day of the evaluation, depending on the goal of the evaluation. If your child takes a non-stimulant medication for ADHD or ADD (i.e. Straterra) they should take it as usual the day of the evaluation.
I agree with this for now. Maybe the cooperation work can come later.