Thank you for asking this question! I often wonder and would like the answer from someone who has done extensive studies. My daughter is 23 having been first considered bi-polar at the age of 17 when she experienced her first manic episode. She was then diagnosed bi-polar when the symptoms persisted.
From my own perspective: Looking back, I would have never given her the ADD stimulant drugs! I would have instead insisted that the teachers work with her to help her overcome her learning disabilities. She was always a well behaved child throughout her years in school but had difficulty concentrating and following instructions. This drug induced state masked her real issues, challenges...she found her own ways to get by in school (often having the top students assisting her) until diagnosed at the age of 11 with ADHD. At that time she was prescribed adderall (spelling?).
In high school, she never used illegal drugs, struggled constantly in class to make grades having been coded with a math reasoning disability, couldn't memorize to pass a test (she often had open book tests especially in foreign language), ran track, played soccer and had close friends. However, after completing two years of college she is still unable to hold a job for more than a couple months.
Micaela readily suffers from anxiety and the related symptoms of bi-polar. She is on Zyprexa and an anti-depressant. She lives independently with the financial help of me. Her manic episodes are typically triggered by stress of the work place and being told she needs to "go faster" and has made mistakes. These are the exact same issues she has had since the age of five when in kindergarten. They have followed her throughout life never being addressed for what they really were...a learning disability!
In our constant struggle to trouble-shoot Micaela's anxiety/episodes we always come up with the same conclusion - being on the stimulants never allowed for her to learn coping skills. Aren't these skills we should all learn to prepare us for life? Ironically, my sister's son has a learning disability and was taken off the stimulants (at 11 or so) as he had a reaction to them (ticks?). Therefore, he learned coping skills throughout his years in school. He is now a productive, confident 23 year old working adult.
School isn't only about making it convenient for teachers to teach the basics but they should be willing/able to teach those that are learning challenged without the use of medication! I am now trying to teach her coping skills she never learned while being medicated on stimulants. We discuss almost daily how to cope with the anxiety of her hidden (after all you can't see it!) disability and why employers aren't patient!
In summary, I can see why so many children are quickly given stimulants for ADD. It has become our culture not to look further...an easy fix...quick, fast, a magic pill. Well, it is now coming back as other issues!
In summary, of course this is my own unique personal experience I feel compelled to share based on your question. I hope someone, somewhere does a study now that we have a portion of the generation of adults that were medicated with stimulants as children.