An 82-Year-Old Man Is Brought to the Emergency Department by His

An 82-year-old man is brought to the emergency department by his daughter due to severe depression and a 6.8-kg (15-lb) weight loss over the past month.  The daughter reports that he remains depressed, despite treatment with therapeutic doses of sertraline, and is withdrawn from the family.  She says, "He no longer plays with the grandchildren, has been eating poorly, and wanders around the house at night when he can't sleep."  The daughter became alarmed when she found him talking aloud to his wife, who died 20 years ago.  In his 40s, the patient was diagnosed with depression, which responded to a tricyclic antidepressant at that time.  Medical history includes hypertension and hypercholesterolemia, both well controlled with medication.
In the hospital, the patient is alert and oriented but gives minimal responses.  Efforts to get him to eat and drink are unsuccessful.  He reluctantly discloses that he hears voices and has thoughts of suicide.
Vital signs are normal and physical examination is unremarkable aside from weight loss.
Extensive laboratory testing shows mild dehydration but is otherwise within normal limits.  CT scan of the brain shows no acute processes.
Which of the following is the most appropriate treatment for this patient?

A) Discontinue sertraline and start antipsychotic medication
B) Initiate electroconvulsive therapy
C) Switch to a different selective serotonin reuptake inhibitor
D) Switch to a norepinephrine-dopamine reuptake inhibitor
E) Switch to a tricyclic antidepressant