[Major depressive episode with psychotic features and vitamin B12 deficiency : a neuropsychiatric interplay]

Psychotic depression is a high-risk clinical entity associated with increased morbidity, mortality, and suicide risk, yet it remains frequently underdiagnosed. We report the case of a patient hospitalized for a depressive episode that evolved into psychotic symptoms and a catatonic episode in the context of vitamin B12 deficiency without anemia. This case highlights the difficulty of differentiating psychotic depression from neuropsychiatric manifestations related to cobalamin deficiency, which may mimic, trigger, or exacerbate depressive, psychotic, and catatonic symptoms. Diagnostic investigations revealed vitamin B12 malabsorption associated with neurological involvement. Combined treatment with vitamin B12 supplementation and antidepressant-antipsychotic therapy led to clinical improvement. This vignette underscores the importance of targeted screening for vitamin B12 deficiency in atypical, treatment-resistant, or neurologically associated psychiatric presentations.