B12 deficiency and psychiatric disorders: case report and literature review.

Although an association of psychiatric symptoms with vitamin B12 deficiency is well accepted, the incidence and nature of these symptoms is not established. To help illuminate the natural history of this illness we review the literature regarding psychopathology associated with B12 deficiency and examine 15 cases, including one of our own, that meet specified criteria for B12-responsive psychosis. In the accepted cases the most common psychiatric symptoms were organic brain syndrome, paranoia, violence, and depression. Several of the patients were not anemic and had no neurologic deficit. Examination of blood smears or obtaining of serum B12 levels should be considered for patients with the symptoms described.