Major Depressive Disorder

A 38-year-old woman presents to the psychiatry outpatient clinic with a 3-month history of persistent low mood, loss of interest in her job as a schoolteacher, and difficulty concentrating on routine tasks. She reports waking up at 4 AM daily, unable to return to sleep, and has lost 6 kg unintentionally. She denies suicidal ideation but feels life is not worth living. Her appetite is markedly reduced. Mental status examination reveals psychomotor retardation, depressed affect, and impoverished speech. There is no history of mania or hypomania. Thyroid function tests and vitamin B12 levels are normal. What is the most likely diagnosis?

A 52-year-old man with a history of Major Depressive Disorder, currently on sertraline 100 mg daily for 8 weeks, returns to the psychiatry clinic. He reports persistent depressed mood, anhedonia, and fatigue despite compliance with medication. His wife notes no improvement in his social withdrawal or irritability. Vital signs are stable, and there are no contraindications to dose escalation. What is the most appropriate next step in management?

Which of the following neurotransmitter systems is primarily implicated in the pathophysiology of Major Depressive Disorder according to the monoamine hypothesis?

According to DSM-5 criteria, what is the minimum duration of symptoms required for a diagnosis of Major Depressive Disorder?

A 38-year-old woman presents with a 3-week history of persistent depressed mood, anhedonia, sleep disturbance, and feelings of worthlessness. She has no significant past psychiatric history and no contraindications to antidepressants. Which is the drug of choice for first-line treatment of her major depressive disorder?