The dexamethasone suppression test and depressive signs in dementia

The non-suppression by dexamethasone of endogenous cortisol production has been held to be a specific and sensitive indicator of biological depression. Non-suppression has, however, been reported in a proportion of patients with severe dementia. In the present study failure of suppression was found in 10 out of 20 demented patients. The non-suppressors scored significantly higher on a scale of signs of depression. Following antidepressant treatment, 3 out of 8 non-suppressors reverted to normal suppression, but this was not associated with clinical improvements. The implications of these findings are discussed.