Chronic caffeine consumption and the dexamethasone suppression test in depression.

Acute caffeine administration increases cortisol and converts the dexamethasone suppression test (DST) to nonsuppression in normal humans; data concerning chronic administration as well as effects in depressed patients are minimal. To determine whether caffeine intake influenced DST results in depression, we retrospectively studied the relationship between regular daily caffeine consumption and pretreatment DST status in major depressives. Daily intake was not correlated with either post-DST cortisol levels or symptom ratings. These data suggest that chronic caffeine use is unlikely to be a major factor in dysregulation of the hypothalamic-pituitary-adrenal axis in depression, perhaps because of the development of tolerance.