There's a discussion over on BTF about Rob Bell's panic attacks. Since I have some experience on this subject, I added my two cents, which I'll reprint here:
Panic attacks, panic disorder and anxiety disorders are all slightly different things. I'll talk about panic attacks and panic disorder, because I've dealt with them myself.
Panic attacks are when your body's sympathetic nervous system (a/k/a your fight-or-flight system) kicks into gear at inappropriate times. It can happen for no reason. In my case, my first panic attack happened as I was loading the dishwasher after a dinner of fettucine alfredo.
Now it's a good thing to feel anxious and afraid, to have your heart start racing and your breathing to get faster and shallower, when a lion is chasing you. That's why we have this fight-or-flight system. But it's not much help when you're trying to load a dishwasher.
Panic disorder can happen as a result of a panic attack. Here's how it works: our brain stores memories much more quickly and effectively when the memory is associated with an emotional event. Strong emotions are a shortcut to memory building.
A panic attack is a strong, emotional event. What your brain does (automatically, not consciously) is to take a snapshot of the environment during the event. Your brain isn't sure which of the elements of the environment is the cause of the emotional event, so it makes an association with everything it can.
Anytime thereafter that you encounter one of those elements, your brain is put on alert for that event to happen again.
So in my case, my brain associated the panic attack with dishwashers and pasta. For the next couple of weeks every time I had to do the dishes, or eat pasta, I felt nervous and on edge.
Panic disorder happens when you confront this environment again, and it triggers another panic attack. This in turn strengthens the association in the brain with that environment, and it becomes a vicious circle.
If Rob Bell had a panic attack on the baseball field, his brain may have made similar associations with his environment, and he could have fallen into a similar vicious circle. He could be perfectly fine off the field, and only panic when he gets onto the field.
There are basically two methods to cure/prevent panic disorder. One is to go back to that environment repeatedly, and retrain your brain that this environment is not dangerous. The other is with medication to suppress the flight-or-fight response. Or both.
Fortunately for me, I was able to avoid the vicious circle without medication. But I can sympathize with those who need it. Who would want to live their lives afraid of baseball or pasta?