I have found Yoga to be an extremely helpful practice to manage the issues that stem from ADHD. Additionally, the physical aspect of Hatha is extremely beneficial to counteract the side effects of the ADHD medication I take.
With any learning or psychological difficulties, the best way to manage is to balance the body, mind, and spirit, since the problem is often the result of an imbalance. For instance, in ADHD the right brain is functioning at a higher capacity than the left so there is an imbalance in the use of each. Yoga is a holistic practice so it will not cause further imbalances by strengthening one part and not another.