RESUMO
Objective To investigate the difference of niacin skin flush response between patients with major depressive disorder (MDD) and healthy controls (HCs), and its sensitivity and specificity for the diagnosis of MDD. Methods Twenty-one untreated patients with MDD and 28 age- and gender-matched HCs were enrolled in this study. The severity of depressive symptoms was assessed mainly by using the 17-item Hamilton Depression Rating Scale (HDRS-17). Methyl Nicotinate (MN) solution at 8 different concentrations (10-5 mol/L, 10-4 mol/L, 10-3.5 mol/L, 10-3 mol/L, 10-2.5 mol/L, 10-2 mol/L, 10-1.5 mol/L, 10-1 mol/L) were applied on subjects' forearms. Signals of blood flow were collected using the Doppler Laser Flowmetry to detect the skin flushing of the test. Results Under the concentrations of 10-2.5 mol/L, 10-2 mol/L, 10-1.5 mol/L and 10-1 mol/L MN solution, the blood flow was significantly higher in depressive patients than in HCs (P<0.01). The MN sensitivity (logEC50) was inversely correlated to the severity of depressive symptoms (r=-0.57, P<0.05). ROC curve analysis implied that the maximum blood flow (MBF) caused by the niacin skin flush response, could efficiently discriminate MDD from HCs (AUC=0.90, P<0.01). Conclusion The presence of enhanced niacin skin flush response may be helpful in the diagnosis of MDD.