That's an interesting question. My son definitely has periods when I would swear that he was drunk or high. Not so if he's got a methylphenidate patch on.
When he was younger I did a long trial of not feeding him any dairy, based on the theory that some digested milk proteins are bioactive (Meisel, et al., Z Ernahrungswiss 28:267-278 (1989)), but the trial was not well-controlled and was inconclusive. The same has been said about peptides derived from soy proteins, but it's tough to get that out of most foods.
In the end, he was a happy kid, although a bit goofy, and I opted to let him be happy.

I think you should talk to the prescribing MD concerning this

maybe something in his diet? I've read that gluten and yeast sensitivities can cause an almost drunk like effect.