Characteristics of panic disorder patients responding to placebo.

Forty-one panic disorder patients receiving placebo were investigated in a double-blind comparison of alprazolam, imipramine and placebo in panic disorder. A significantly higher drop-out rate was found in the placebo group than in the active treatment groups, but placebo response was found in 34% of the patients, defined as reduction of panic attacks to zero, and in 23%, defined as a score of greater than or equal to 8 on the Physician Global Improvement Scale (0-10 points). Several predictors of response to placebo were found. The responders had fewer panic attacks than the nonresponders at baseline. They also reported less psychopathology and were less help-seeking than the nonresponders. The implications for psychopathology and possible response to psychotherapy among responders and nonresponders are discussed. It is hypothesized that the responders show more signs of realistic processing of internal and external stimuli and fewer signs of subjective distress than the nonresponders. Responders will therefore probably be more responsive to psychotherapy than nonresponders.