Occurrence of high concentrations of postdexamethasone cortisol in elderly psychiatric inpatients

The authors retrospectively studied 161 psychiatric inpatients who had received a dexamethasone suppression test (DST). The majority of the patients were over 60 years old, female, and had concurrent chronic medical illnesses. Age was significantly correlated with log-transformed postdexamethasone cortisol concentrations in the 118 nondemented patients with major depression. Four p.m. cortisol concentrations greater than 15 micrograms/dl occurred in 15 patients. All were over 60 years old; all but one had major depressive disorder (MDD); and five had dementia plus MDD. In the same population, a 5 micrograms/dl criterion did not distinguish MDD from non-MDD patients. The results support the existence of a clinically relevant age effect on the DST in patients with MDD. Elderly depressed patients with markedly elevated cortisol concentrations occur frequently, and warrant further clinical and pathophysiological study.