The dexamethasone suppression test as a biologic marker of depression in chronic pain

The relationship between chronic pain and depression has become enmeshed in the literature. In an attempt to unravel the relationship between chronic pain and depression, the authors studied a uniform group of 80 chronic back pain patients with and without depression using the dexamethasone suppression test (DST). The DST examines the hypothalamic response to an exogenously administered steroid (dexamethasone) challenge. In normal subjects and patients without major depression, the dexamethasone suppresses the release of cortisol from the adrenal glands. In 40% of patients with major depression, there is an early escape of cortisol from dexamethasone suppression. We found that 40% of patients with a DSM-III major depression (dysphoric mood, appetite and sleep changes, loss of energy and interest, decreased concentration, suicidal ideation, and feelings of self-reproach) were non-suppressors and none of the patients without major depression showed this abnormality. These findings suggest that the concept of chronic pain as a variant of depression might be an oversimplification.