I think the qualitative difference is when the personality traits interfere with basic living. To put it differently, everyone is producing brain cells. Some

I think the qualitative difference is when the personality traits interfere with basic living. To put it differently, everyone is producing brain cells. Some people are producing more brain cells. However, when they're producing so many brain cells that the brain stops functioning properly, we start calling it a tumor. In the same way, everyone gets nervous and anxious from time to time. As a personality trait, I'm more high strung than most people. The fact that I don't like roller coasters and crowds due to that reason is just a personality trait. The fact that I once lost necessary medication because I was too nervous to speak with the cashier at the drug store made it a disorder.