Friend thinks he has split split personalities?

my friend claims he has split personalities and i think hes just a crack head he sais his alter ago is damien (his name is christian) weird huh? he sais this alter ego is always thinking cant stay on one topic and he sais certain people trigger it like his other freind alex his dad and lexi i think this "alter ego" is just a way to deal with stress for him (lexi recently broke his heart) (his dad is a total **** up) and alec.. im not sure... any thoughts?