This study looks at how well a new drug, aticaprant, works with regular antidepressants to prevent depression symptoms from coming back. Depression symptoms include feeling sad and losing interest or pleasure in things. The new drug, aticaprant, will be tested against a placebo (a fake pill with no medicine) to see if it helps more. The study will include people who feel better after taking aticaprant with their antidepressant. To join, you need to be healthy based on a physical exam and have a history of major depressive disorder (MDD) diagnosed by a doctor. You should also have symptoms of anhedonia, which means not enjoying things you used to like. People who have not responded to many different antidepressants or have certain health issues cannot join.

• The study involves taking aticaprant with an antidepressant.
• You cannot join if you have certain health issues or have not responded to other antidepressants.
• Participants should not have problems with alcohol or drugs recently.