Association between the dexamethasone suppression test and serotonin transporter availability in healthy volunteers - A SPECT with [¹²³I] ADAM study

Most common psychiatric diseases have been found to be associated with disturbance of both the hypothalamic-pituitary-adrenal (HPA) axis and the brain serotonergic system. The aim of this study was to explore the neuroendocrine relationships between the dexamethasone suppression test (DST) and serotonin transporter (SERT) availability in healthy volunteers. Sixty-six participants (30 males and 36 females) were recruited from the community. The DST suppression rate (D%) is the reduction in cortisol level from Day 1 (D1) to Day 2 (D2) in proportion to the Day 1 cortisol level (D%=(D1-D2)/D1×100%). SPECT with [¹²³I] ADAM was used to measure SERT availability. A significant correlation between D% and SERT availability was noted in all subjects (Spearman's ρ=0.26, p=0.03) and in the male subjects (Spearman's ρ=0.41, p=0.02). SERT availability may be sensitive to changes in DST, especially in males.