Study to Evaluate the Efficacy and Safety of Once-Weekly Oral NBI-1065846 in the Treatment of Anhedonia in MDD

Key Inclusion Criteria: Participants must meet all of the following key inclusion criteria: 1. Completed written informed consent. 2. Aged 18 to 65 years, inclusive, at the time of informed consent. 3. Primary diagnosis of MDD. 4. Participants must meet one of the following criteria: * must have been taking ≥1 antidepressant medication(s) for ≥8 weeks prior to screening. * must have received ≥1 antidepressant medication(s) for ≥8 weeks in the current or most recent episode of depression. 5. Snaith Hamilton Pleasure Scale (SHAPS) score is ≥30 at screening and Day 1. Key Exclusion Criteria: Participants will be excluded from the study if they meet any of the following key criteria: 1. Any psychiatric disorder disallowed per protocol and electroconvulsive therapy (ECT) within 6 months prior to screening. Comorbid anxiety disorders are not exclusionary. 2. Have a significant risk of suicidal or violent behavior. 3. A history of seizure disorder, stroke, Alzheimer disease, Parkinson disease, multiple sclerosis, head injury associated with loss of consciousness for more than 15 minutes, or other neurodegenerative disorder.