What condition can lead to subacute combined degeneration of the spinal cord?

Subacute combined degeneration of the spinal cord is primarily associated with vitamin B12 deficiency. This condition arises due to the disruption in the myelination process of the spinal cord's dorsal columns and corticospinal tracts. Vitamin B12 is crucial for maintaining the integrity of the myelin sheath, which is essential for proper nerve function. A deficiency in this vitamin leads to neurological symptoms, which can include sensory disturbances, weakness, and spasticity.

In cases of vitamin B12 deficiency, the body experiences inadequate levels of methylcobalamin and adenosylcobalamin, which are necessary for DNA synthesis and myelin formation. This deficiency often arises from malabsorption issues, dietary insufficiencies, or certain medical conditions like pernicious anemia. The progressive damage and degeneration of the nervous system structures result in the clinical manifestations associated with subacute combined degeneration.

While other deficiencies, such as those of vitamin D, iron, and folic acid, can lead to various health issues, they do not specifically cause the myelin damage characteristic of subacute combined degeneration. Therefore, understanding the unique role of vitamin B12 in nerve health clarifies why it is linked to this condition.