A doctor vs psychologist= who understands adhd better?

Depends: They both could be doctors. Psychologists can be phd's, while the other might be a do or md. Do's & md's can write prescriptions but psychologists cannot. Even though I am a physician, i try to find the gal cause of the adhd symptoms and treat those rather than covering adhd symptoms with drugs.

Chicken or the egg?: The title behind the professional is not as important as the years of expertise in the subject matter, the level of interest and compasion for the patients problems, and your ease , trust and communication with him/her.Md and psychologists are part of a comprehensive team of professionals, not mutually exclusive, i propose you see both!

ADHD: ADHD is best handled with BOTH medication annd therapy. Go to an MD (psychiatrist) for an initial evaluation and med management thereafter, AND go to a reputable psychotherapist who specializes in ADHD issues.