How "blind" are double-blind studies?

J Consult Clin Psychol. 1991 Feb;59(1):184-7. doi: 10.1037//0022-006x.59.1.184.


Psychopharmacological studies usually attempt to eliminate "nonspecific" influences on outcome by double-blind designs. In a randomized, double-blind comparison of alprazolam, imipramine, and placebo, the great majority of panic disorder patients (N = 59) and their physicians were able to rate accurately whether active drug or placebo had been given. Moreover, physicians could distinguish between the two types of active drugs. Inasmuch as correct rating was possible halfway through treatment, concerns about the internal validity of the double-blind strategy arise.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Alprazolam / therapeutic use
  • Anxiety Disorders / diagnosis
  • Anxiety Disorders / drug therapy
  • Double-Blind Method*
  • Female
  • Humans
  • Imipramine / therapeutic use
  • Male
  • Middle Aged
  • Panic
  • Placebos
  • Psychotherapy


  • Placebos
  • Imipramine
  • Alprazolam