Published online by Cambridge University Press: 07 November 2014
Augmentation strategies have become popular in patients with a partial response or residual symptoms. In a survey conducted by the American Society of Consultant Pharmacists, 65% of 169 psychiatrists indicated that they would augment treatment as the next step in a partial responder in contrast to non-responders in whom they would switch to another drug (J.C. Nelson, unpublished data). This decision is based on common sense and practicality rather than empirical evidence. Many clinicians and patients think that if a patient achieves at least a partial response to a medication, it makes sense to continue that drug and add a second. To some extent, the patient preferences for treatment shown in the Systematic Treatment Alternatives to Relieve Depression (STAR*D) study reflect this approach. This discussion will update clinicians on the use of augmentation agents for the treatment of major depressive disorder (MDD).
Lithium augmentation has been used since it was first described by de Montigny and colleagues in 1981. This strategy is based on a rational neurochemical hypothesis that lithium has a synergistic effect when added to a tricyclic antidepressant (TCA). Lithium increases serotonin turnover and the TCA increases postsynaptic serotonin receptor sensitivity. Recent debates have focused on whether lithium is as effective combined with selective serotonin reuptake inhibitors (SSRIs) as it is combined with a TCA. The rapid effects sometimes observed with lithium augmentation of TCAs does not seem to occur with SSRIs, conceivably because SSRIs do not increase postsynaptic serotonin receptor sensitivity.