Valproate augmentation in a subgroup of patients with treatment-resistant unipolar depression

Objectives: About 50% of patients with unipolar depression suffer from treatment-resistant depression (TRD). Animal studies have suggested potential antidepressant properties of valproate (VPA) possibly due to its implication in epigenetic programming. Methods: Fourteen TRD patients (seven males and seven females; age 19-59) received VPA (375-1000 mg/day) in addition to their treatment regimen after previously failing to respond to two or more antidepressant trials and/or different combinations. Clinical response to VPA was investigated prior the treatment (T-0) and after 1 (T-1), 4 (T-4) and 7 (T-7) months of therapy using the Montgomery-Asberg Depression Rating Scale (MADRS) and the Clinical Global Impression (CGI). Results: Compared to T-0, VPA significantly decreased MADRS score at T-1 (P < 0.001), T-4 (P < 0.001) and T-7 (P < 0.001) (partial η2=0.86). Importantly, MADRS score at T-7 (13.6 ± 1.6, mean ± SEM) was closer to the reported value of remission (MADRS <10), and none of the patients relapsed during the observational period. Compared to T-0, VPA also decreased CGI-Severity of illness score at T-1 (p = 0.03), T-4 (p < 0.001) and T-7 (p < 0.001) (partial η2 = 0.74). Conclusions: Antidepressant augmentation with VPA provided substantial clinical improvement and maintenance over a relatively long-term period in a subgroup of patients with severe TRD. VPA thus deserves further exploration in large double-blind clinical trials.