Im cyclothymic, and during my depressed periods, most "existential" things scare me.
I once broke down crying because I was deeply upset, confused and frightened that there were no universal moral rules, since morality would be largely subjective. (I study philosophy) I honestly was so scared I was crying. And as anyone here with depression, bipolar or a similiar disorder knows, add that to the terrifying feeling depression brings, and you are going to walk in front of a lorry just to get away from it. Strangely enough, more "trivial" things like spiders, the dark and the like have absolutely no effect on me.
During my manic periods, nothing scares me. I am too happy and creative to even think about fears. (If Im not studying them, smiling and now and then flailing my hands around shouting "Whoop de doo, there's so much to learn and to do!")
And when Im in between, spiders, a lot of attention, losing people I love... You know, all the regular things that most people feel.