Pain sensitivity, evoked potentials, and the dexamethasone suppression test in depressed patients

Nonsuppression of cortisol following dexamethasone may identify a biologically homogeneous subgroup of psychiatric patients. This article reports two studies examining pain sensitivity and sensory inhibition measured by evoked potential augmenting/reducing in dexamethasone test (DST) suppressors and nonsuppressors. Since nonsuppression may be related to elevated levels of adrenocorticotropic hormone (ACTH) and, perhaps, endogenous opiates, pain sensitivity and augmenting/reducing may differ between suppressors and nonsuppressors. Results indicate that nonsuppressors lack sensory inhibition and that evoked potential augmenting/reducing is correlated strongly with pain sensitivity only in nonsuppressors. These results are consistent with the hypothesis that the DST identifies biologically different subgroups of depression.