From what I have learned through research it is a chemical imbalance in the brain that causes hair-trigger anxiety
reflexes, so to speak. I have severe anxiety
, have had panic attacks since the age of 12 - so do many, many members of my family. Even some folks who have never had a heart palpitation in my family have severe anxiety. So, I don't think it's a physical condition (at least not as they are commonly thought of) with most people, but an imbalance of brain chemicals.