A panic attack is defined as a sudden, unexpected (seems to come out of the blue) rush of intense fear or dread. It is common for the first panic attack to occur during stressful times in life, when there is worry that coping with a given situation will be very difficult.
Physical symptoms of a panic attack can include shortness of breath or smothering feelings, dizziness, feeling faint or unsteady, racing or pounding heart, trembling or shaking, sweating, choking sensations, nausea or abdominal distress, feelings of being detached or of things seeming unreal, numbness or tingling sensations, hot flashes or cold chills, chest pain or discomfort.
Fears stemming from these uncomfortable physical sensations include going crazy, losing control, and dying. These fears will persist within a person even when they are no longer in a state of panic, leading to chronic worrying about additional panic attacks and the subsequent monitoring of body sensations that may indicate the onset of an attack, not to mention high levels of physical tension in general. With increased awareness of bodily sensations and more anxiety concerning vulnerability to an attack, a person is more prone to future attacks.
Additionally contributing to the problem is avoidance. While the initial panic attacks appear to be random, over time, people begin to associate the experience of panic with people, places, and situations in which attacks previously took place. This leads to the avoidance of potential anxiety-triggers, greatly reinforcing the fear of future panic attacks. The more people run away from their fears, the more fearful they will become!
Panic Disorder is diagnosed when unexpected panic attacks become very frequent and at least one of these attacks is followed by a month or more of worrying about future attacks and/or the meaning of the attacks (e.g., "I am going crazy"). Behavioral changes, such as avoiding the last place in which you had an attack are also very common. When a person's avoidance of life's situations becomes extreme, Panic Disorder with Agoraphobia may be the appropriate diagnosis. These diagnoses should only be made by mental health professionals.
The treatment for Panic Disorder is focused on increasing the tolerance for anxiety and for tension in general, preventing anxiety from escalating into a full-blown panic attack. This requires learning how to deal effectively with anxiety when it appears, working on the cognitions that are fueling the panic (e.g., "I am losing control"), and more importantly, increasing ones willingness to approach situations where panic might occur. Treatments tend to be short term.