Women are nearly twice as likely as men to be affected by anxiety disorders. Anxiety is an alerting signal that warns of impending danger and enables a person to take measures to deal with a threat. It prevents damage by alerting one to actions that forestall danger. Anxiety disorders include generalized anxiety disorder, panic disorder, social anxiety disorder, and specific phobias. Panic disorder is characterized by recurrent unexpected panic attacks followed by at least one month of concerns about additional attacks. Biological, psychological, and social factors all contribute to anxiety disorders. Treatment involves behavioral therapy and medication management.