Antipsychotics as antidepressants: what is the mechanism?

Antidepressants are first-line treatment for patients with major depressive disorder (MDD). The mechanism of action of antidepressants is still not completely understood. While most antidepressants directly inhibit the reuptake of at least one monoamine neurotransmitter in the brain (serotonin, dopamine or noradrenalin), or block their degradation, mirtazapine, tianeptine and agomelatine, which are also similarly effective as other antidepressant drugs, do not act this way. Despite the availability of large number of antidepressants of different classes, significant portion of patients do not achieve remission, (Rush et al. 2006), and treatmentresistance is common (Nemeroff 2007). EFFICACY OF ANTIPSYCHOTICS IN MDD