A case is presented of a 65-year-old man with chronic schizophrenia who, af
ter four years of remission, developed psychotic symptoms after pneumonia.
The patient was found to be deficient in vitamin B12. His psychosis remitte
d within 5 days of administration of vitamin B12 and folic acid. This case
emphasizes the need to measure vitamin B12 in psychogeriatric patients, esp
ecially when they present with a severe infection and organic mental sympto
ms.