Psychiatryniche
A 34-year-old man who came to Australia from Somalia six years ago is reviewed by his general practitioner for a depressive episode. After eight weeks of sertraline 100 mg daily, which a tablet count confirms he has taken reliably, he is no better: he sleeps four hours a night, has lost 6 kg and is short-tempered with his wife. He smokes 25 cigarettes a day and chews khat with friends most afternoons at a community house. He has had only intermittent night-shift cleaning work since a back injury, and his mother in Mogadishu has been unwell. Which one of the following best explains his poor response to treatment?