RecruitingPhase 3Drug trialA Study of Seltorexant as Monotherapy in Adults and Elderly Participants With Major Depressive DisorderThe main purpose of this study is to assess how well the study drug (JNJ-42847922) works (efficacy) compared with placebo in improving depressive symptoms in participants with major depressive disorder (\[MDD\], a common mood disorder that causes a lasting feeling of sadness and a loss of interest in everyday activities) in double-blind treatment phase. Further, to evaluate long-term safety and tolerability of JNJ-42847922 in participants with MDD in the open label treatment phase.