Behavioral Therapy Behavioral treatments including systematic desensitization are among the most effective treatments for panic disorder wirh agoraphobia First the therapist and client define the phobicstimulus Together they define a hoerarchy for the phobic stimulus The client and therapist then expose the client to events on the hierarchy that increase the client's degree of anxiety as the client and therapist move through the hierarchy the client progressively masters increasing levels of anxiety until she or he encounters the phobic stimulus