A Multicenter, Double-blind, Randomized, Placebo-controlled Study to Evaluate Efficacy and Safety of Seltorexant as Monotherapy in Adult and Elderly Participants With Major Depressive Disorder (MDD) and an Open-label Long-term Extension Treatment With Seltorexant
The 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.
• Meet diagnostic and statistical manual of mental disorders-5th edition (DSM-5) diagnostic criteria for major depressive disorder (MDD), without psychotic features based upon clinical assessment
• Experienced at least one MDD episode prior to their current episode
• Current episode of MDD must be a minimum of 2 weeks in duration
• Must meet one of the following criteria regarding current medication status.
‣ Can be presenting for a new episode of MDD on no antidepressant treatment; however, must have been treated with an antidepressant medication in a prior episode for a minimum of 6 weeks at a stable dose at or above the minimum therapeutic level (medical record/source document).
‣ OR
⁃ Have taken up to two antidepressant treatments started in the current episode that were stopped (withdrawn), or will be withdrawn (washed out) due to inadequate response or intolerance.
• Body Mass Index (BMI) between 18 and 40 kilograms per square meter (kg/m\^2)
• Must be medically stable on the basis of the following performed at screening and double-blind (DB) baseline: physical examination (including a brief neurological examination), vital signs (including blood pressure), and 12-lead electrocardiogram (ECG)