It's hard to say.
Your best bet would be to talk to a therapist. His ADHD may be comorbid with something else. Bipolar disorder may be a possibility.
A therapist would be good for him on another level. Medication may help with helping the brain function better, but it doesn't teach him communication skills, problem solving skills, or overall social skills, which would overall help his self-confidence, self-respect, and self-esteem.
I faced similar challenges growing up myself (high IQ, low social skills, labelled "gifted", low self-esteem, etc.). However, my ADD diagnosis didn't come until recently...and I'm 26 years old.
Interesting enough, some people with ADD/ADHD alone (that is, the ADD/ADHD is not comorbid with anything else) have depression and anxiety symptoms, although there is debate going on as to whether these are side effects of ADD/ADHD or if these are just ways to cope with the disorder. Honestly, I think it's the latter. The anxiety comes from being afraid of failing and the depression comes from the actual sensation of "failure".
