My personal experience and that of one of my adult children in particular is similar, so I'll share some positive (?) and also admit that I remain unconvinced that the diagnosis is accurate as far as its name.   (I know that line is confusing).  Son first: NO evidence of adhd in school.  In terms of performance or disruptive class behavior or observed hyperactivity at home or in school.  Pleasure to have in class.   "Gifted" support recommended since 1st? grade.   Junior high comes.  Tough for kids anyway.  Grades, which have not always been straight A's even though bright, really challenging.   Homework, I had noticed, had always been a difficult thing.  Keeping track of things....GREAT on things of his particular interest...not so great on others.  When he began to show signs (associating with academically unmotivated and sometimes troubled students, me suspicious of depression though would never be noticed by anyone else-probably ever)....saw counselor/psychiatrist.   Her "diagnosis" - she was careful, I believe,  NOT to use that word  "some concentration issues and some anxiety/depression" .  I mention his situation because it was helped with Concerta and Wellbutrin.  After awhile he stopped and seemed ok....later, a sleeping disorder (I know this sounds like alot, but these things seem to often go hand in hand) ...corrected by a complicated surgery.....seems to have corrected almost all of these issues.   He is a freshman in college.  He does not take medication.  However, he is fully aware that he must stay tuned to the possibility of depression creeping up, due to significant family history.    SO:  no definitive diagnosis (stated to a teen, thus avoiding label) - but treatment on basis of concentration and depression/anxiety.  Finally, in high school the other issue came to light--too long for here- but sleep disorder because antidepressants weren't helping, was recommended.   Wish I'd not put it off because it was a blessing to him.  Not so for everyone, of course.   Now ME: Treatment for years for what I self diagnosed as "dysthymia" the word when I started, for long, ongoing, I guess mild depression.  Treatment was trial and error, using SSRI Prozac, then Effexor and finally Wellbutrin due to wt gain issue w/other.  At some point, with alot of reading...I realized I might want to ask about using Ritalin or some stimulant to help with the depression because I must have felt it was worse.  Or better, but not right.  To my surprise, the doctor was NOT surprised....was fully aware that stimulants are sometimes used to augment antidepressants...like a booster.   I was prescribed Concerta.  I went back after taking it and said..."I think its helping some.....but, should I be feeling calmer?  Its kinda strange...I seem to be feeling less anxiety or agitation or something.. wouldn't the stimulant have made me more wound up...I was worried about that.  His answer - yes, it is absolutely possible that you feel more calm...this is what we use to treat ADHD. If you are already aware of this....you know that its strange, but this treatment and how I reacted to it was almost the only way I have myself convinced that there is an element of ADHD for ME.   THough NO background that would indicate this anywhere in a negative way.  There is such a fine line between ADHD and BP and no way to (blood test) really definitively say which, that the effectiveness of the treatment remains sometimes the key to the mystery of diagnosis.   SO --while I am very much against labels in this department-- I know the doctor has to have some place to begin.  Had I become overly agitated...it probably would have looked like...uh oh...stop this med...we may trigger some kind of manic thing.  I have NEVER had a manic episode and continue to be treated for Depression and "rule out" bipolar, which means "haven't ruled out" bipolar apparently. Here's the bottom line.   It makes me feel better, so I do take the Concerta.  I take it and notice calming effect within half and hour.   I also take it as augmentation for the antidepressant.  AND, in my case, it was helpful in losing weight I had gained (way too much to be healthy)along the other antidepressant way.   I hope some of this helps.  I have learned alot from www.dbpalliance.org (may be wrong web address) and NAMI - talking to others.  I stopped reading for awhile because I needed a break.....so you may find more up to date info there, but at the time, it was clear many people were being treated very cautiously, the way I was.....cautious because if they weren't sure of BP or ADHD, and prescribed a stimulant....it might be BP and cause mania.

I'm lucky it did the opposite with me, which might indicate some level of adhd.   THe hyperactivity is NOT an issue, the "inattentive"  (concentration) issue I could see.   Hope some of this helps.