Purely opinion, and we never had (or needed) any official diagnosis, but yes, I think poor placement/lack of services can have a drastic enough effect in a child to cause some major emotional issues.
We saw it with DS7. He's always been a HIGHLY rule-abiding child--think Spock! He tattled on himself if he did anything he even thought MIGHT be wrong! He was not prone to emotional outbursts of any sort, and he was generally cheerful and easy to be with.
But he hit 1st grade with no challenge and no differentiation, and he began acting out, missing recess, and being angry and belligerent at home. He was clearly an unhappy, troubled child, and he knew exactly what the problem was: school.
If such a situation went on for a long time, I have no doubt that he would have had major emotional problems. He was a miserable kid.
And, yes, all the bad behavior and emotional disturbance went away the SECOND we pulled him out of that classroom for homeschooling. He had only been in that class for 6 or 8 weeks, so there wasn't a long transition period. He immediately went back to his cooperative, cheerful, easygoing self. There was no doubt about the cause and effect of the change!
