MAOA and major depressive disorder: The underlying mechanism of induction of MAO-A activity in IR group is still unclear, but these results can help to explain the symptoms of depression reported in iron-deficient population (Corwin et al., 2003), since increased MAO-A activity has been linked to mood disorders (Meyer et al., 2009; Sacher et al., 2015; Kolla et al., 2016).