There is an obvious increase in what seems to be called ADHD or ADD and what if that is the next stage compartmentalization of thought in a world where a person has to process multiple identity points and deal with different societal reactions? We are at a nexus explosion of input to a species that had never had it before, if you were to look at it from an outside view, and it would be probable the increase in learning disabilities like ADHD come from an oversaturation of media to a mind that needs other ways to absorb it cognitively. OMG I am posting these thoughts to a science fiction BBS and hoping for real discussion. I must be going crazy.
I'd tend to wonder if it's more biology or behavioral? People in general are rarely willing to "wait their turn", instead focusing for a moment to interject rather than listen. Otherwise, I don't think it's an increase in incidence so much as in capacity for diagnosis. Like, they made Asperger's obsolete because the classification itself was based on incomplete (i.e.: northern european males only) study samples leading to lack of recognition in other statistical groups.
Fun fact: the Batman comics toyed with the idea that Joker wasn't batshit crazy but instead had a form of "super-sanity" that allowed his mind to adjust instantly to wildly-changing circumstances. He still shot a woman in the spine just to see if he could cause her dad to have a breakdown though.