You do not need to be officially diagnosed with panic disorder to have an attack. Some people have only one or two panic attacks in their life and don't have panic disorder. Panic attacks are actually much more common than panic disorder. According to one Harvard Medical School survey, about 23 percent of people interviewed experienced at least one panic attack in their lifetime, while only about 3 percent of people experienced panic disorder in their lifetime. (1)
The condition of steady, pervasive anxiety is called Generalized Anxiety Disorder. Yet there are numerous anxiety-related disorders. One is panic disorder—severe episodes of anxiety that occur in response to specific triggers. Another is obsessive-compulsive disorder, marked by persistent intrusive thoughts or compulsions to carry out specific behaviors, such as hand-washing. Post-traumatic stress disorder may develop after exposure to a terrifying event in which severe physical harm occurred or was threatened. Anxiety so frequently co-occurs with depression that the two are thought to be twin faces of one disorder. Like depression, anxiety strikes twice as many adult females as males.
Occasional anxiety is an expected part of life. You might feel anxious when faced with a problem at work, before taking a test, or before making an important decision. But anxiety disorders involve more than temporary worry or fear. For a person with an anxiety disorder, the anxiety does not go away and can get worse over time. The symptoms can interfere with daily activities such as job performance, school work, and relationships.