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Is It Alzheimer’s Disease or Vitamin B12 Deficiency?

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Updated June 27, 2014

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

Have you or a loved one experienced these signs of Alzheimer’s recently?

While you could be experiencing these symptoms due to Alzheimer’s or another dementia, it’s also possible that your symptoms could be related to low levels of vitamin B12.

Several studies have been conducted to establish the link between vitamin B12 and Alzheimer’s. Some, such as the study highlighted here, associate low B12 levels with both the symptoms of Alzheimer’s and actual atrophy (shrinkage) of the brain. Other studies have attempted to prove that B12 supplements restored cognitive functioning to previous levels after supplementation.

What Is Vitamin B12 Deficiency?

As the name suggests, vitamin B12 deficiency is when there is not enough of the B12 vitamin in your body.

Symptoms of Vitamin B12 Deficiency

In addition to the above symptoms (memory loss, behavior changes and agitation) which are similar to the symptoms of Alzheimer’s, people with low B12 may also experience the following:

  • Weight loss
  • Fatigue
  • Weakness
  • Constipation
  • Poor balance
  • Tingling or numbness in hands or feet
  • Depression
  • Sore mouth or tongue

Causes of Vitamin B12 Deficiency

Some cases of low B12 vitamin levels are related to other disease conditions, including pernicious anemia, tapeworms, Crohn’s disease, and celiac disease. Other cases are caused by alcoholism or by a poor vegetarian diet that does not provide enough nutrients.

Another risk factor is increased age, since B12 absorption can decline as people age.

Treatment of Vitamin B12 Deficiency

Treatment of low levels of vitamin B12 is quite simple. If your B12 levels are low, you generally will be prescribed a higher dose of the vitamin, either through injections or a pill you can take by mouth. Your blood levels are then tested regularly and the vitamin dose is adjusted to the appropriate level.

Preventing Vitamin B12 Deficiency

One way to prevent low levels of vitamin B12 is to eat a diet rich in B12. This includes liver, beef, clams, several kinds of fish, fortified cereals and other sources as well.

Some people take an extra dose of vitamin B12, perhaps as part of their daily vitamin or in a supplemental vitamin as a precaution against developing the condition. Check with your physician to make sure the amount of B12 is appropriate for you. If your B12 levels are not low, your physician may recommend not taking any extra vitamin B12 as extra amounts have not been proven to be beneficial.

Diagnosing Vitamin B12 Deficiency

Diagnosing vitamin B12 deficiency is accomplished by taking a sample of your blood and testing it to determine the level of vitamin B12 in your system. Normal results are between 200-900 pg/mL (picograms per milliliter). Older adults, however, may experience some symptoms of vitamin B12 deficiency even at levels of 200-500 pg/mL and benefit from supplemental doses of B12.

Vitamin B12 Deficiency and Its Relationship to Alzheimer’s

When being evaluated for Alzheimer’s or another dementia, in addition to mental status tests and imaging tests, ask for a blood test to evaluate your vitamin B12 level. Researchers estimate that as many as 1.5% to 15% of the population is deficient in B12 levels, and this is especially true of older adults, whose bodies absorb B12 less efficiently than others.

The Good News About a Diagnosis of Vitamin B12 Deficiency

A diagnosis is B12 deficiency may be a reversible cause of confusion and behavior changes. In other words, it’s possible that increasing your B12 level can improve or restore your memory and ability to think clearly, as well as resolve the other symptoms you may be experiencing such as fatigue and weakness. While Alzheimer’s research continues, there currently are few effective long-term treatments, and Alzheimer’s is not reversible. A diagnosis of low B12 levels has the potential to be far more responsive to treatment than Alzheimer’s, and while symptoms may not completely disappear, it's possible they may improve as your B12 levels are adjusted.

Sources:

Medline Plus. Anemia- Vitamin B12 Deficiency. Accessed December 19, 2011. http://www.nlm.nih.gov/medlineplus/ency/article/000574.htm

Medline Plus. Vitamin B12 Level. Accessed December 28, 2011. http://www.nlm.nih.gov/medlineplus/ency/article/003705.htm

Office of Dietary Supplements. National Institutes of Health. Dietary Supplement Fact Sheet: Vitamin B12. Accessed December 28, 2011. http://ods.od.nih.gov/factsheets/vitaminb12/

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