This study is a multi-center trial consisting of a 12-week open-label treatment period (OLP), followed by a 12-week double-blind, placebo-controlled, randomized withdrawal period (DBRWP). During the OLP, subjects receive open-label AXS-14. Subjects achieving treatment response will be randomized into the DBRWP in a 1:1 ratio to either continue on AXS-14 or switch to placebo for up to 12 weeks or until a loss of therapeutic response occurs.