Cobalamin deficiency presenting as obsessive compulsive disorder: case report.

Cobalamin deficiency commonly presents with a wide range of neuropsychiatric manifestations ranging from myelopathy, neuropathy, optic neuritis and dementia to mood disorders, chronic fatigue and psychosis even without classical hematological abnormalities like anemia and macrocytosis. However, obsessive compulsive disorder (OCD) in relation to vitamin B12 deficiency has not been described so far. We report a case of middle-aged man presenting with OCD, low serum cobalamin and a positive family history of vitamin B12 deficiency who responded well to methylcobalamin replacement.