My brother is bi-polar (possibly aspergers) has always lived with my mom (who makes way too much money to have ever gotten assistance), my brother gets Food Stamps as well as somehow he got health insurance too. He got it all finally after one of his jail stints, while he was in the half way house... he has since maintained it.
He is 25 now, so I think it is possible, it might vary state to state perhaps.
If he is over 22, he can be considered a separate household if he prepares and eats his food separately from the other family members. The key words here are "separate household" and "prepares and eats separately".
He could get the food stamps in our state also if he prepares , eats, and stores the food separately. The caseworker sometimes comes to the household to check out the food storage system and to make sure the recepient's food is actually kept in a separate place. It seems like a lot of work and expense (for the individual and the state) to me when a single person is only eligible for a very small amount of food stamps.