Pernicious Anemia Is a Neurological Disease
I. Pernicious Anemia Is a Demyelinating Neurological Disease
Pernicious anemia (PA) is an autoimmune disorder in which vitamin B12 cannot be adequately absorbed or utilized, leading to progressive neurological injury.
Autoimmune failure of vitamin B12 absorption disrupts methylation and fatty acid metabolism essential for myelin maintenance and repair, producing central and peripheral demyelination, tract-specific spinal cord injury (classically subacute combined degeneration), and widespread cognitive, emotional, and psychiatric manifestations. These neurological effects frequently precede anemia and may occur in its absence.
Pernicious anemia (PA) typically has an insidious onset, with early symptoms that are nonspecific and easily misattributed. As a result, diagnosis is often delayed several years from symptom onset to receive a correct diagnosis, and a substantial proportion are initially misdiagnosed or not diagnosed at all. During this period, neurological injury continues to accumulate. Clinicians are therefore often faced with patients who already have advanced neural involvement by the time the underlying disorder is recognized.
Because myelin repair is metabolically demanding and time-dependent, outcomes depend not only on correcting cellular B12 deficiency but on interacting system constraints rather than hematologic markers alone.
Understanding how this injury unfolds, and why its effects vary so widely, requires looking beyond any single pathway.