A Pilot, Proof of Concept, Placebo-controlled Trial of Candesartan as an Adjunctive Treatment for Bipolar Depression

Pharmacological options for the treatment of Bipolar disorder (BD) are limited and a large proportion of patients does not show adequate response to treatment, especially in the case of bipolar depression. It has been hypothesized that dysfunctions in the renin-angiotensin system (RAS) may be involved in the pathophysiology of BD. We propose a double-blind, randomized, placebo-controlled, cross-over, proof-of-concept trial to investigate the effects of candesartan, an angiotensin-II receptor antagonist capable to cross the blood-brain barrier, as an adjunctive agent in the treatment of bipolar depression. Bipolar patients on a depressive episode will be randomly assigned to undergo two consecutive 4-week treatment periods with either candesartan (4 mg daily) or placebo in a crossover study. At the beginning of each treatment period, participants will complete a resting-state functional MRI scan, to be performed 1.5 hours after the first dose of the study medication. Subjects will be followed weekly and the Montgomery-Asberg Depression Rating Scale (MADRS) will be adopted as the primary outcome measure. Response will be defined as a decrease equal or higher than 50% in the MADRS score from the time of study entry to the 4th week of each treatment period. Possible associations between changes in brain connectivity (measured through resting state functional MRI) and subsequent response to treatment will also be analyzed.