A 45-year-old man presents 5 weeks after being laid off from his job of 20 years. He reports persistent depressed mood, anhedonia, insomnia, poor concentration, fatigue, feelings of worthlessness, and a 10-pound weight loss. He denies suicidal ideation. He states that he thinks about the job loss constantly and that his symptoms began within 2 weeks of the layoff. He has no prior psychiatric history and no family history of mood disorders. He notes that he briefly felt better when his former colleague offered to help him network but then quickly returned to feeling hopeless. Which clinical feature most clearly supports a diagnosis of major depressive disorder rather than adjustment disorder with depressed mood in this patient?