A 74-year-old man is brought in by his daughter for 6 weeks of "memory loss." The decline began relatively abruptly and has an identifiable start around the time his wife died. On testing he frequently answers "I don't know" and appears unmotivated to try, but with encouragement he can register and recall items. He reports poor appetite, early-morning awakening, and feeling worthless. His orientation is intact and he is distressed by his memory complaints. Which finding most strongly favors a reversible depressive pseudodementia over a neurodegenerative dementia?