Vitamin B12 deficiency is a common condition that manifests classically with megaloblastic anaemia. However, neuropsychiatric disorders can occur as the first manifestation of vitamin B12 deficiency. Herein, we reported two cases with neuropsychiatric disorders as the first manifestation. The first was an Indian man who presented with an unsteady gait and numbness in the lower limbs associated with low back pain and normal hemoglobin with normocytosis. MR images were consistent with subacute combined degeneration of the spinal cord. Vitamin B12 level was found to be low. The second case was an Indian man without a psychiatric history who was brought to the emergency room because of abnormal behavior and poor sleep. His blood study and brain images were normal. The deterioration of his condition in addition to being vegetarian prompted the attending physician to look for another cause of his illness. Vitamin B12 was low. Both patients received B12 supplements and showed significant improvement.
Key words: subacute combined degeneration, vitamin B12 deficiency, macrocytosis, catatonia