Neurology
Pernicious anemia
Pernicious anemia is an autoimmune cause of vitamin B12 deficiency resulting from loss of intrinsic factor due to autoimmune gastritis, leading to megaloblastic anemia and neurological dysfunction. It predominantly affects older adults and is associated with other autoimmune diseases and an elevated risk of gastric neoplasia. Lifelong vitamin B12 replacement is required once diagnosed.
Synesthesia
Synesthesia is a neurological condition where the stimulation of one sensory or cognitive pathway leads to involuntary experiences in another pathway, such as perceiving colors when hearing music or associating specific tastes with words.
Vitamin B12
Vitamin B12, or cobalamin, is a water‑soluble vitamin essential for neurologic function, red blood cell formation, and DNA synthesis. It is naturally present in animal-derived foods and certain fortified products, absorbed in the ileum via an intrinsic factor–mediated process, and functions as a cofactor for methionine synthase and methylmalonyl‑CoA mutase. Deficiency can cause megaloblastic anemia and neuropathy and is most common in older adults, people with malabsorption, and individuals following strict vegan diets.