Vortioxetine (Lu AA21004) 10 and 20 mg for Treatment of Major Depressive Disorder With Sexual Dysfunction

The drug being tested in this study is called Lu AA21004. Lu AA21004 is being tested to treat people who have major depressive disorder (MDD). This study will look at sexual function in people who take Lu AA21004. The study will enroll approximately 440 patients. Participants will be randomly assigned (by chance, like flipping a coin) to one of the two treatment groups-which will remain undisclosed to the patient and study doctor during the study (unless there is an urgent medical need): * Lu AA21004 10 to 20 mg * Escitalopram 10 to 20 mg - This is a comparator drug that is also used to treat MDD. All participants will be asked to take one tablet at the same time each day throughout the study. All participants will be asked to answer questionnaires at each study visit. This multi-centre trial will be conducted in the United States and Canada. The overall time to participate in this study is 14 weeks. Participants will make 7 visits to the clinic, and will be contacted by telephone 21 days after last dose of study drug for a follow-up assessment.