Vitamin B₁₂ Deficiency Manifested as Psychosis Without Anemia

Ms. A was a 52-year-old woman with a 3-month history of acute paralysis of the lower extremities and a 1-month history of paranoid delusions of persecution, delirium, and severe agitation. Ms. A had no significant prior medical or psychiatric history nor any history of drug or alcohol use. Up until 3 months before, she had been in excellent health, happily married, and employed. Ms. A had consulted a neurologist at the onset of her weakness in the lower extremities and was diagnosed with multiple sclerosis. Over the next several weeks, she was placed on a regimen of medications including carbamazepine, amitriptyline, tramadol, diazepam, prednisone, thiamine, and multivitamins. Despite this, her weakness worsened. She required a cane, then a walker, and finally a wheelchair to get around just 3 months after the onset of her symptoms.

In the month preceding our interview, Ms. A’s neurological symptoms had been overshadowed by the acute onset of psychiatric symptoms. She had become increasingly agitated and short tempered with her family, on several occasions throwing furniture at them and once trying to exit a moving car to escape them. She had even called the police several times to report her family for attempting to poison her food. Her family eventually brought her to the emergency room of a state mental health center, where in her first interview with us, she appeared disheveled and uncooperative and had a labile mood and affect. She also showed evidence of delirium, with waxing and waning alertness, anger, and loss of aspects of both her long- and short-term memory.

An examination revealed large bilateral patches of desquamated skin on her feet and normal oral mucosa. Her cranial nerves were intact. Ms. A was, however, unable to stand unassisted. A right Babinski reflex was present, as well as a bilateral loss of proprioception, vibration, and sensation of light touch and pain in the lower extremities. Strength and reflexes in the lower extremities were bilaterally symmetric and grossly diminished. Results of tests of the upper extremities were normal. Ms. A’s CBC results were normal, as were her serum folate and iron levels. Serum vitamin B₁₂ levels were measured and were found to be markedly diminished—less than 9 pg/ml (normal=200–950 pg/ml).

Ms. A was diagnosed with subacute combined spinal cord degeneration and psychosis due to severe vitamin B₁₂ deficiency. She received intramuscular vitamin B₁₂ injections and was transferred to a medical facility. Subsequent test results revealed intrinsic factor and parietal cell antibodies in her serum, as well as elevated levels of methylmalonic acid (23 µmol/liter; normal, <0.4 µmol/liter) and homocysteine (26 µmol/liter; normal, <13 µmol/liter). An endoscopic gastric biopsy revealed atrophic gastritis with prominent intestinal metaplasia.