Anxiety disorders include disorders that share features of excessive fear and anxiety
and related behavioral disturbances. Fear is the emotional response to real or perceived
imminent threat, whereas anxiety is anticipation of future threat. Obviously, these
two states overlap, but they also differ, with fear more often associated with surges of autonomic
arousal necessary for fight or flight, thoughts of immediate danger, and escape
behaviors, and anxiety more often associated with muscle tension and vigilance in preparation
for future danger and cautious or avoidant behaviors. Sometimes the level of fear
or anxiety is reduced by pervasive avoidance behaviors. Panic attacks feature prominently
within the anxiety disorders as a particular type of fear response. Panic attacks are not limited
to anxiety disorders but rather can be seen in other mental disorders as well.