A disorder characterised by sudden attacks of fear and panic. The episodes may resemble a heart attack. They may strike at any time and occur without a known reason but more frequently are triggered by specific events or thoughts, such as taking an elevator or driving. The attacks may be so terrifying that some people associate their attacks with the place they occurred and will refuse to go there again. Symptoms of panic attacks may include tachycardia (rapid heartbeat), chest pressure or pain, shortness of breath, dizziness, tingling, and anxiety. Hyperventilation, agitation, and withdrawal are common results.

It is generally thought that panic disorder is due to an abnormality of the brain. This abnormality may inappropriately activate the body's hormonal system and cause a sudden "fight or flight" response. People with panic disorder have been found to have reductions of a type of serotonin receptor, called 5-HT1A, in three areas of the brain -- the anterior and posterior cingulates and the raphe, which has connexions to a region that processes emotion. These findings lend credence to the concept that serotonin dysfunction plays a role in the disorder.

Treatment of panic disorder may include medications and/or cognitive behavioural therapy using controlled exposure of the patient to known triggers of their panic attacks to reduce their symptoms of panic.