Not every problem can be medicated away. He sounds immature. That's not a form of "brain disease," necessarily. That's a failure to get past the developmental milestones that growing up involves.

Maybe he was poorly reared . . . maybe some bad attitudes were role modeled for him by influential adults in his life, when he was young . . . maybe he wasn't shown the love it takes to make a child grow up having an inner core of security. None of that is much remedied by taking pharmaceutical products. We tend to want there to be a technological fix for human inadequacy. We want to think that all problems are solvable through science.

Failure to mature tends to become hard-wired after a certain point in a young person's life. A person just gets so far behind that they then lack the wherewithal to catch up. They become perpetually childlike and a burden to a spouse, who will never find in this person a real peer and companion.