Agoraphobia refers to a fear of being in places where escape might be difficult, or where help might be unavailable in case of a panic attack. The exact cause of panic disorder is unknown, but it is associated with multiple physiological factors and is very responsive to biological treatment. Panic disorder can occur with or without agoraphobia , but agoraphobia develops in more than one-third of cases. The development of agoraphobia may involve learned behavior, since it reflects a fear of experiencing panic attacks in unprotected settings, and sometimes the association of panic attacks with areas where they have occurred. Panic disorder with agoraphobia can occur in children, but the age of onset is usually between adolescence and the mid-30s.
Panic disorder affects middle-aged and older adults as well.