Vitamin B12 and the elderly
Vitamin B12 deficiency, which affects 10-15% of adults over the age of 60, is frequently associated with neurological manifestations. Compared to younger individuals, this vitamin deficiency is more common in older adults because of the higher prevalence of food-bound vitamin B12 malabsorption (atrophic gastritis) and the higher incidence of the autoimmune condition, pernicious anemia. Hematological changes, including elevated blood levels of homocysteine and methylmalonic acid, are diagnostic of vitamin B12 deficiency.
However, approximately 25% of cases include neurological symptoms as the only clinical indicator of vitamin B12 deficiency. Such neurologic symptoms of vitamin B12 deficiency include numbness and tingling of the extremities, especially the legs; difficulty walking; concentration problems; memory loss; disorientation; and dementia that may or may not be accompanied by mood changes. In some cases, the dementia and other neurologic symptoms caused by vitamin B12 deficiency can be reversed by vitamin treatment, but reversibility seems to be dependent upon the duration of the associated neurologic complications.
While the biochemical mechanisms underlying the neurological effects of vitamin B12 deficiency are not understood, the vitamin deficiency is known to damage the myelin sheath covering cranial, spinal, and peripheral nerves.