Anxiety, which can also refer to a syndrome, is a mood response to an internal threat that could be the expectation of an external threat. It is an emotional response that is out of proportion with any genuine threat found in the environment. Furthermore, instead of being directed towards a current stimulus, anxiety is associated with the anticipation of a future problem. Anxiety differs from fear in that fea r is a response to an immediate external, genuine threat. Physiologically, the symptoms of anxiety accord to those for fear, including nausea, light-headedness, shortness of breath, and increased heart rate--the typical fight-or-flight response; yet when there is no genuine danger in the environment, these symptoms can be extremely aversive and stressful for the individual. Although personal distress can lead to functional impairment, the diagnostic criteria for the syndrome of anxiety disorders only requires that the individual experience grave personal distress. There are several diagnostic categories for anxiety disorders: panic disorder with or without agoraphobia, agoraphobia with panic disorder, obsessive-compulsive disorder ( OCD), specific phobia, social phobia, posttraumatic stress disorder (PTSD), acute stress disorder (ASD), and generalized anxiety disorder.…