Vitamin B12 deficiency can affect which parts of the nervous system?

Vitamin B12 deficiency can affect which parts of the nervous system?

• A. Peripheral nerves
• B. Spinal cord
• C. Brain
• D. Peripheral nerves, spinal cord, and brain

Answer: (D)

B12 is essential for myelin maintenance across the nervous system, so deficiency disrupts myelin formation in both the central and peripheral nervous systems. When myelin is affected in the peripheral nerves, a symmetric sensory and motor polyneuropathy can develop, causing numbness, tingling, and weakness. In the spinal cord, demyelination—especially of the dorsal columns and lateral pathways—leads to impaired position and vibration sense, gait ataxia, and spasticity from motor tract involvement. In the brain, insufficient myelin and related metabolic effects can produce cognitive changes, mood disturbances, or even dementia-like symptoms. Because B12 deficiency can impact myelin throughout the CNS and PNS, it can involve peripheral nerves, the spinal cord, and the brain, making all three areas susceptible.

B12 is essential for myelin maintenance across the nervous system, so deficiency disrupts myelin formation in both the central and peripheral nervous systems. When myelin is affected in the peripheral nerves, a symmetric sensory and motor polyneuropathy can develop, causing numbness, tingling, and weakness. In the spinal cord, demyelination—especially of the dorsal columns and lateral pathways—leads to impaired position and vibration sense, gait ataxia, and spasticity from motor tract involvement. In the brain, insufficient myelin and related metabolic effects can produce cognitive changes, mood disturbances, or even dementia-like symptoms. Because B12 deficiency can impact myelin throughout the CNS and PNS, it can involve peripheral nerves, the spinal cord, and the brain, making all three areas susceptible.