Efficacy of Lu AA21004 on Cognitive Dysfunction in Major Depressive Disorder

Inclusion Criteria

• In the opinion of the investigator, the participant is capable of understanding and complying with protocol requirements.
• The participant or, when applicable, the participant's legally acceptable representative signs and dates a written, informed consent form and any required privacy authorization prior to the initiation of any study procedures.
• The participant has recurrent MDD as the primary diagnosis according to Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR) criteria (classification code 296.3x). The current MDE should be confirmed using the Mini International Neuropsychiatric Interview (MINI) V6.0.0.
• The participant has received prescribed treatment for a previous episode of depression.
• The participant has a MADRS total score ≥26 at both the screening and baseline visits.
• Participant reports subjective cognitive dysfunction (such as difficulty concentrating, slow thinking, and difficulty in learning new things or remembering things).
• The reported duration of the current major depressive episode (MDE) is at least 3 months
• The participant is a man or woman between 18 and 65 years old, inclusive.
• A female participant of childbearing potential who is sexually active with a nonsterilized male partner agrees to routinely use adequate contraception from signing of the informed consent throughout the duration of the study and for 30 days after completion of the study.

Exclusion Criteria

• The participant has previously participated in this study.
• The participant has a history of severe drug allergy or hypersensitivity, or known hypersensitivity to any of the excipients of the investigational medicinal product (IMP).
• The participant has known hypersensitivity to duloxetine.
• The participant has hereditary problems of fructose intolerance, glucose-galactose malabsorption, or sucrose-isomaltase insufficiency.
• The participant is an immediate family member, study site employee, or is in a dependent relationship with a study site employee who is involved in the conduct of this study (e.g., spouse, parent, child, sibling) or may consent under duress.
• The participant has a score ≥70 on the DSST (numbers correct) at the Baseline Visit.
• The participant is, in the opinion of the investigator, not able to complete the neuropsychological tests validly at the Baseline Visit.
• If female, the participant is pregnant or lactating or intending to become pregnant before, during, or within 30 days after participating in this study; or intending to donate ova during such time period.
• The participant has 1 or more of the following:
• Any current psychiatric disorder other than MDD as defined in the DSM-IV-TR (as assessed by the MINI Version 6.0.0).
• Current or history of attention deficit hyperactivity disorder (ADHD), pervasive developmental disorder, manic or hypomanic episode, schizophrenia, or any other psychotic disorder, including major depression with psychotic features, mental retardation, organic mental disorders, or mental disorders due to a general medical condition as defined in the DSM-IV-TR.
• Current diagnosis of alcohol or other substance abuse or dependence (excluding nicotine or caffeine) as defined in the DSM-IV-TR that has not been in sustained full remission for at least 2 years prior to Screening. (Participant must also have negative urine drug screen prior to Baseline).
• Presence or history of a clinically significant neurological disorder (including epilepsy).
• Neurodegenerative disorder (Alzheimer's disease, Parkinson's disease, multiple sclerosis, Huntington's disease, etc).
• Any DSM-IV Axis II disorder that might compromise the study.
• The participant has any other disorder for which the treatment takes priority over treatment of MDD or is likely to interfere with study treatment or impair treatment compliance.
• The participant has physical, cognitive, or language impairment of such sev