Why is this even a debate? ADHD is BY DEFINITION a learning disorder. Learning disorders have nothing to do with IQ, they make it harder to learn. Thats why they're called learning disorders. And speaking as someone who has ADD, the condition is very real. Yes, it is over diagnosed by people gaming the system for more SAT time, but it is definitely real. I score in the ninety-something percent tile for almost every standardized test I've taken, but I almost failed out of school due to not being able to concentrate on lectures or homework. And yes, there is a metric crap-ton of people claiming to have ADD for stupid reasons. But there are credible cognitive tests for proving this disorder, and it has a proven detriment to one's ability to learn.
ADHD happens when brain can't choose what to do. The brain can't choose what to pay attention to, or daydreams during class. So what they need is help so that they could pay attention. But depending on the condition it does effect learning. People with severe ADHD would have will miss something during class because memory is art of attention. So they can't remember what they learned because they weren't paying attention.
ADHD does not exist. There are children in europe and africa that don't have ADHD for example. ADHD is an american thing and thats the problem because we have children sitting for extend periods of time in class and they have problems focusing because it is exhausting to sit for a long time and in high school we only get 3 minutes to switch classes but an hour sitting in class. We need to give our children a chance to stand and stretch or work on hands on that includes standing for some time. Our education system in the U.S. is corrupt right now.