Low baseline salivary 3-methoxy-4-hydroxyphenylglycol (MHPG) in drug-naïve patients with short-illness-duration first episode major depressive disorder

Abstract

BackgroundCentral noradrenergic dysfunction with autonomic nervous system dysregulation are reported in major depressive disorder (MDD). Salivary 3-methoxy-4-hydroxyphenylglycol (sMHPG) is indicative of central noradrenergic activity. Studies on MHPG in bodily fluids are inconsistent and scarce data is available regarding baseline sMHPG concentration in MDD. MethodsThe basal, non-stimulated sMHPG concentration was studied in this cross-sectional case-control study on 20 non-late-life adult, short-illness-duration first-episode, treatment-naïve MDD patients and in 20 age- and sex-matched healthy controls. Depressed patients showed a score in the Hamilton rating scale for depression (HAMD-17) higher than 20. ResultsThe baseline sMHPG concentration was significantly lower in depressed individuals as compared to controls (p=0.025). In post hoc analysis significantly lower sMHPG was present in melancholic MDD (p=0.009) as related to controls whereas no difference was seen between non-melancholic MDD patients and controls. The concentration of sMHPG was not significantly correlated neither with duration nor the severity of depressive symptoms as measured by the total HAMD-17 score. LimitationsThe current study is limited by its cross-sectional design and small sample size. ConclusionLow baseline sMHPG concentration was found in MDD. The study provides no support for elevated sMHPG in drug-naïve patients with short-illness-duration first episode MDD. Taken into account the physiology of sMHPG secretion the study results corroborate with the evidence for decreased central noradrenergic activity in MDD when sMHPG is considered indicative of central noradrenergic function.