America's "baby boomers" are retiring. As they do so, age-related health problems will present a growing burden for families, physicians, and healthcare policymakers.
Alzheimer’s disease is the most common cause of mental decline in elderly persons. After you reach the age of 60, your risk for developing Alzheimer’s doubles every five years. However, Alzheimer’s disease is not the only cause of dementia.
Vitamin B12 deficiency, a relatively common nutritional problem among older individuals, can cause mental impairment that is clinically indistinguishable from Alzheimer’s dementia.
Vitamin B12 Deficiency Is More Common Among the Elderly
Vitamin B12, or cobalamin, is unique in several respects. It is the only vitamin that contains an essential mineral – namely, cobalt. The cobalamin molecule is the largest and most complex of all vitamins. Unlike other B vitamins, significant amounts of B12 are stored in your liver for months or even years. Finally, the absorption of food-bound B12 requires intrinsic factor, a protein secreted from the acid-producing cells in your stomach lining.
As you age, your ability to secrete gastric acid and intrinsic factor declines. Gastric acid is required to free vitamin B12 from your food, and liberated vitamin B12 must then be bound to intrinsic factor so it can be absorbed from your intestine. As B12 absorption gradually falls, your body relies upon your liver stores of the vitamin to support your physiologic needs.
Over the course of many months, your vitamin B12 supplies are depleted, and you begin to exhibit the signs and symptoms of vitamin B12 deficiency.
Vitamin B12 Supports the Function of Two Vital Enzymes
According to the Linus Pauling Institute at Oregon State University, vitamin B12 is a necessary cofactor for methionine synthase, an enzyme that converts homocysteine to the amino acid methionine. Methionine is used to provide one-carbon groups for a variety of critical cellular processes, including the synthesis of DNA and RNA.
B12 is also an essential cofactor for a mutase enzyme – methylmalonyl mutase – that participates in the formation of normal myelin. Myelin is the protective coating that surrounds and insulates your nerve cells. Without robust myelin production, your nervous system cannot function normally.
In addition to supporting the synthesis of myelin, DNA, and RNA, vitamin B12 is needed for metabolizing fats and proteins and for synthesizing hemoglobin, which is the oxygen-carrying pigment in your red blood cells.
Vitamin B12 deficiency leads to a reduction in methylmalonyl mutase and methionine synthase activity, which results in impaired energy production, anemia, and neurological degeneration.
Vitamin B12 Deficiency Is Not Always Associated with Anemia
Due to some overlapping functions of the two nutrients, folate can correct the anemia – but not the nerve damage – caused by vitamin B12 deficiency. Hence, if your diet or vitamin supplement furnishes adequate amounts of folate, you will not develop the anemia that typically accompanies cobalamin deficiency. Therefore, your doctor may not recognize your nutritional deficit, and the neurological injury will progress insidiously.
Early neurological signs and symptoms of vitamin B12 deficiency include mild weakness, reduced reflexes, and a loss of positional and vibratory sensation in your extremities. Later, you may develop muscle spasticity, pathological reflexes (“Babinski’s sign”), an abnormal upturning of your toes following stimulation of the sole of your foot, is classic) and difficulty with walking and balance.
Irritability, depression, confusion, delirium, and paranoia are psychiatric signs of vitamin B12 deficiency, and these can be difficult to distinguish from age-related dementias, such as Alzheimer’s disease. If not treated promptly, the nerve damage caused by vitamin B12 deficiency can be irreversible and possibly even fatal.
Vitamin B12 Levels Should be Checked in All Elderly Persons Exhibiting Signs of Dementia
A simple blood test can rule out vitamin B12 deficiency as the cause of cognitive impairment in an elderly patient. Once diagnosed, vitamin B12 deficiency is easily correctable with either injectable forms of the vitamin or oral supplementation, depending on the severity of the deficiency.
Most elderly patients who develop vitamin B12 deficiency will require lifelong supplementation. B12 injections are not required once the deficiency is corrected, because oral and sublingual preparations of vitamin B12 are more readily absorbed than food-based vitamin B12.
Recommended dietary allowances for vitamin B12 vary from 0.4 mcg daily for infants to 2.8 mcg daily for lactating females. Dr. Elson Haas, author of Staying Healthy with Nutrition, recommends 10 to 20 mcg daily for optimal health and doses up to 100 times those amounts for treating vitamin B12 deficiencies.
Dementia among the elderly represents a growing health care burden in the United States. Vitamin B12 deficiency accounts for a minority of affected persons, but it is easily diagnosed and readily treated – and unnecessarily devastating when it is missed.
Sources:
- Linus Pauling Institute at Oregon State University: Vitamin B12
- The Merck Manual of Diagnosis and Therapy, 18th Edition: Vitamin B12 Deficiency. Mark H. Beers, M.D., Editor-in-Chief; 2006
- Staying Healthy with Nutrition: Vitamin B12 (Cobalamin). Elson M. Haas, M.D.; 2006
Stephen Allen Christensen - Dr. Steve Christensen's writing has appeared in magazines, professional journals, poetry anthologies, and children's books since 1976.
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