combination of sub-optimal brain wiring and sub-optimal early childhood.
fear of death (all fears are essentially just "off-shoots" of fear of death) induced by mundane situations basically. the brain filters events incorrectly and reads things as much more risky and dangerous than they are.
sensory perception difficulties and disordered emotional regulation.
Isn't that basically PTSD? I think a lot of people feel this initial anxiety even if they haven't had any traumatic events in the past.