Caffeine-Induced Escape From Dexamethasone Suppression

To the Editor.—  The dexamethasone suppression test (DST) is employed by clinicians as a sensitive and highly specific tool for the diagnosis of melancholic major depression.¹ Our unit recently reported that the single-dose oral administration of caffeine produces dose-related and statistically significant increases in the plasma cortisol level.² Psychiatric patients, particularly depressed patients, have been reported to consume large quantities of caffeine.^3,4 For these reasons, we investigated the effects of caffeine on the standard DST.

Subjects and Methods.—  Twenty-two normal volunteers and six depressed patients 23 to 60 years of age gave their informed consent to participate in this study. All of the subjects underwent a physical and clinical laboratory examination and were in good health. Except for two normal volunteers receiving oral contraceptive medications, all subjects were drug-free for a minimum of ten days prior to participation in the study. Normal volunteers were allowed to continue