Hello! Please remember that my response is for information only, we are not establishing a therapeutic relationship.
It sounds like there's the possibility that there's more going on with him than just ADD. As you might know from your own experience, not all people with ADD lack motivation and many know their "calling" in life!
I would say the first thing, if he hasn't done so already, is get a full current evaluation by a Psychologist. Psychiatrists tend to do the interview part and prescribe medication, but Psychologists often do other types of testing that can give detailed information about what's going on with a person.
A different drug might help with his ADD, but it sounds like he needs help sticking with taking that drug. Coaching and/or therapy could help him in that regard. As I'm sure you know, all the drugs for ADD help with focus, but they don't target the other problems you've mentioned. For some, the ability to focus helps eliminate those other problems, but for others the other problems need to be targeted directly. It sounds like that could be the case for your son.
If he doesn't like taking medication, maybe he would prefer Neurofeedback
? Neurofeedback enables a person to train their brain waves to function more efficiently and can help reduce ADD symptoms significantly. You can read more about it here: www.eeginfo.com
Cognitive Behavioral Therapy is very useful for all the problems you've mentioned --ADD, Anxiety, Depression. CBT examines the interplay between beliefs, emotions, behavior, and feelings in one's body when in a particular situation. Intervention in one area will affect the entire system. With CBT one does a lot of work with identifying beliefs and making counter or alternative beliefs to the irrational ones. These are then tested out in real life situations in the form of "experiments." It is a highly effective approach. You can read more about it here: www.mindovermood.com and here www.nacbt.org/whatiscbt.htm
Please follow up with me regarding any of the points I've raised or anything that my response triggers for you. I'm happy to work with you until you are satisfied, and would prefer that you continue to ask questions until you can give me an excellent rating!