Introduction: Evidence for excessive monoamine lowering processes such as elevated brain monoamine oxidase A levels have been reported during major depressive episodes (MDE) of major depressive disorder (MDD). We have conducted a series of studies to explore whether monoamine oxidase A (MAO-A) binding is greater during states for which risk of a MDE may be elevated, including MDD in recovery, cigarette withdrawal, and early postpartum.

Methods: MAO-A V_T, an index of MAO-A levels was measured in prefrontal and anterior cingulate cortex, as well as other brain regions implicated in mood disorders (dorsal putamen, ventral striatum, thalamus, hippocampus, midbrain) in healthy subjects (n=28), MDE subjects (n=16), recovered MDD subjects (n=18), otherwise healthy subjects in early cigarette withdrawal (n=10), and otherwise healthy subjects in early postpartum (n=15).

Results: In recovered MDD subjects, prefrontal and anterior cingulate cortex MAO-AV_T were highly elevated prior to recurrence of MDE. During acute cigarette withdrawal and early postpartum, MAO-A V_T was also significantly elevated in prefrontal and anterior cingulate cortex.

Conclusions: Greater MAO-A levels in prefrontal and anterior cingulate cortex may occur at times of high risk for MDE. Future investigations should consider the role of monoamine lowering processes in predisposition for MDE.