That combination -- ADHD, ODD, anxiety-- is also often seen in autism spectrum disorders. We found with our DS (now 11, Asperger's/autism) that he was oppositional/defiant or just tuned out when asked to do something that didn't interest him-- he saw no reason to comply. He is still far better motivated as a self-driven learner than as a school learner, but this has improved with ABA therapy.
On the meds issue: DS11 gets a long-acting ADHD med in the morning, but needs a short-acting booster dose in the afternoon to hold him together till evening. This makes activities possible, and makes our lives more pleasant.
HTH
DeeDee
