Panic Disorder and Agoraphobia

Panic disorder is characterized by recurrent unexpected panic attacks that can occur with or without agoraphobia. Agoraphobia is a disabling condition in which patients fear places in which escape might be difficult. Whether occurring as distinct disorders or together, panic disorder and agoraphobia are common, sometimes disabling, conditions.

Epidemiology

Panic disorder occurs more frequently in women, with a lifetime prevalence of 2% to 3%. The typical onset is in the 20s, with most cases beginning before age 30.

Agoraphobia also occurs more frequent1y in women, with a lifetime prevalence of between 2% and 6%. Only one third of patients with agoraphobia also have panic disorder. However, most patients with agoraphobia seen clinically also have panic disorder. This apparent contradiction is due to the fact that patients with agoraphobia alone are unlikely to seek treatment.

Etiology

The etiology of panic disorder is unknown. There are several popular biologic theories involving carbon dioxide (C0 2 ) hypersensitivity, abnormalities in lactate metabolism, an abnormality of the locus coeruleus (a region in the brain that regulates 1evel of arousal), and e1evated central nervous system catecholamine levels. The gamma-amino butyric acid (GABA) receptor also has been implicated as etiologic since patients respond well to benzodiazepines and panic is induced in patients with anxiety disorders using GABA antagonists.

Theorists posit that panic attacks are a conditioned response to a fearful situation. For example, a person has an automobile accident and experiences severe anxiety, including palpitations. Thereafter, palpitations alone, experienced during exercise or any sympathetic nervous system response, may induce the conditioned response of a panic attack.

Clinical Manifestations

History and Mental Status Examination Panic disorder is characterized by recurrent unexpected panic attacks that can occur with or without agoraphobia (see below). Panic attacks typically come on suddenly, peak within minutes, and last 5 to 30 minutes. The patient must experience 4 of 13 typical symptoms of panic outlined in Table 3-2.

To warrant the diagnosis, one of the following must occur for at least 1 month: persistent concern about having additional attacks, worry about the implications of the attack (losing control, "going crazy"), or a significant change of behavior related to the attacks (e.g., restriction of activities).

Agoraphobia is a disabling complication of panic disorder but can also occur in patients with no history of panic disorder. It is characterized by an intense fear of places or situations in which escape might be difficult (or embarrassing). Patients with agoraphobia and panic disorder typically fear having a panic attack in a public place and being embarrassed or unable to escape. Those with agoraphobia alone (two thirds of those with agoraphobia) simply avoid public arenas but do not have panic attacks.