Psychosis as the Initial Manifestation of Pernicious Anemia in a Type 1 Diabetes Mellitus Patient

Pernicious anemia is a common autoimmune disease with a prevalence of 0.15% to 1% in the general population and 2.6 to 4% in type 1 diabetes mellitus patients. We report a patient with type 1 diabetes who initially presented with isolated psychiatric manifestations, characterized by delusions of persecution, visual, and auditory hallucinations with catatonic symptoms. She was diagnosed as having depression with psychotic features. Six months later, she presented gait ataxia and lower limb weakness. Vitamin B12 deficiency was suspected. Complete blood cell count showed pancytopenia. Vitamin B12 levels were undetectable. Endoscopy with biopsy was performed, showing features of autoimmune atrophic gastritis. Antiparietal cell antibody levels were normal, but anti-intrinsic factor antibody levels were high, confirming the diagnosis of pernicious anemia. After 1 week of vitamin B12 treatment, the patient showed an amazing amelioration of mood and a major improvement in balance and muscular strength. Seven months after the beginning of treatment, psychiatric symptoms were gone. Our report highlights the importance of searching for a secondary cause in every person with psychotic manifestations.