Psychiatry because the ability to cope with massive changes over and over again would be very hard on the mind. When we are young we absorb knowledge and can adapt easy, it gets harder as we get older because we form neural pathways. It is a bit harder as you get older, imagine how hard it might be after 300 years of life and having to go through 6 or 7 societal shifts that require you to change how you interact with people based on what is considered socially acceptable.