Almost off-topic, but for those among us who have anxiety and panic attacks, adding flavor to Parkinson's:

Why Has Natural Selection Left Us So Vulnerable to Anxiety and Mood Disorders?

Randolph M Nesse, MD1
Can J Psychiatry. 2011;56(12):705–706.

http://publications.cpa-apc.org/media.php?mid=1257

…some conditions that seem like diseases are actually defences…
…
. This means that 999 times out of 1000 your panic response will be a false alarm, but nonetheless normal.…

.. the problem is not in logical cognition, it is in the intensity of the anxiety response.

a panic attack is a normal response that is useful in the face of life-threatening danger, and panic disorder results from false alarms in that system, some of which are to be expected, just as they are in smoke detectors…

…Much of what general medicine does is to use medications to block normal defensive responses, such as pain, cough, and fever..,