Age and the dexamethasone suppression test: results from a broad unselected patient population

We examined the relationship between age and postdexamethasone serum cortisol concentration in 676 psychiatric inpatients with a variety of DSM-III diagnoses. Regardless of diagnosis, patients 65 years and older had significantly higher nonsuppression rates than those below age 65 (64% vs. 34%). The correlation between age and cortisol level was moderate, but significant. Aging is associated with increasing nonsuppression rates to dexamethasone, and this change is augmented by an affective disorder diagnosis. Levels of nonsuppression and age-cortisol correlations vary depending on dose of dexamethasone, diagnosis, and gender.