Anxiety Attacks and Panic

In your study and coaching career have you found that the longer a person has battled a way of thinking the more time or more difficult it is to change the thought?

If a person has experienced anxiety and panic attacks for years does it take longer for the brain to rewire in order to stop having panic attacks?
Obviously wrong thinking has produced the fear and the result is anxiety and panic. On a scientific level though we have neuro pathways in the brain that have been there a long time producing negative results.

And what about getting to the root of a long term problem or way of thinking, or can all things no matter how long they have been occurring be changed with simply using the model?

Thank you!