From what I know, it's not based on a true story. Although every story has some sort of truth to it. Seeing the syndrome is caused by a great amount of stress, (Due to other factors.) people in reality also have these issues. Over stressed people everywhere crash. Although their stressed over a different reason in most cases, I assume some very paranoid people feel like their being followed, and the lurking presence of someone. Of course I'm referring to Rena's story.
I think it's not a full true event, but does have connections to reality.