I'm assuming American: Severe social anxiety, touch aversion, ptsd, strong desire for routine. Weight gain in the first few months.
Also a long time to adjust to how rude people are in public spaces compared to inside. Inside disrespect => violence.
My older brother did a few shorter stints over about 10 years but hasn't been back for about 8 years or so. He still has a hard time dealing with crowds + parties but that may be his personality too.
He just needed personal space and time to adjust. It took him about the same amount of time as his sentences to get back to comparable normalcy. He has never been quite the same though. Much less outgoing. I miss the brother I had and I appreciate the one I have now.
Sippin' on that bubb-less