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How does pernicious anemia contribute to nervous system damage?

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Pernicious anemia contributes to nervous system damage by causing a deficiency of vitamin B12, which is essential for maintaining the myelin sheath that protects nerve fibers. In patients with pernicious anemia, the stomach fails to produce intrinsic factor, a substance necessary for the absorption of this vitamin.213

When vitamin B12 levels are inadequate, the body cannot properly synthesize the fatty acids required for the myelin sheath, leading to a condition known as subacute combined degeneration. This results in the demyelination of the corticospinal tracts and dorsal columns of the spinal cord, as well as peripheral nerve fibers.41

The clinical consequences of this degeneration include neuropathy, characterized by symptoms such as tingling, numbness, weakness, mental disturbances, and vision changes. If the deficiency persists, it can lead to instability of gait or paralysis. While treatment with vitamin B12 can often improve symptoms, neurological damage caused by this deficiency is frequently not fully reversible.4213