Salivary 5-hydroxyindole acetic acid (5-HIAA) in drug-naïve patients with short-illness-duration first episode major depressive disorder.

OBJECTIVES Central serotonergic dysfunction is reported in major depressive disorder (MDD). Serotonin is primarily metabolized to 5-hydroxyindole acetic acid (5-HIAA) and its plasma, urinary or cerebrospinal fluid concentrations were extensively studied in depression. No data is available on salivary 5-HIAA (s5-HIAA) in MDD to date. METHODS The basal, non-stimulated s5-HIAA 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. RESULTS No significant difference in s5-HIAA concentration between patients with MDD and controls was observed. In post hoc analysis significantly lower s5-HIAA was seen in non-melancholic MDD (p=0.026) as related to controls whereas no difference was seen between melancholic MDD patients and controls. The concentration of s5-HIAA was not significantly correlated neither with duration nor the severity of depressive symptoms as measured by the total HAMD-17 score. CONCLUSION No difference was observed in baseline s5-HIAA concentration between MDD patients and healthy controls. That observation corroborates with previous MDD studies on 5-HIAA concentrations in bodily fluids where unaltered 5-HIAA concentration is seen in the absence of serotonin-related behaviours including impulsivity, suicidality, and anxiety. Salivary 5-HIAA use remains to be determined.