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Vitamin B12 and Dementia: What’s the Connection?

Written by Melissa Lee
 about the author
14 minute readLast updated June 1, 2022

A deficiency of B12 and dementia share some symptoms. However, symptoms of B12 deficiency may be reversible, while dementia symptoms typically worsen with time. Limited studies have shown possible connections between B12 deficiency and dementia, with some evidence even pointing to B12 supplementation as a way to offset cognitive decline. However, the research is conflicting. More studies are needed to understand the relationship between cognitive decline and B12 deficiency. Read on to learn more about how B12 deficiency can mimic dementia.

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What is vitamin B12?

As an essential vitamin in the body, B12 helps to maintain the health of nerve cells, including brain cells and DNA, according to the National Institutes of Health (NIH).
This water-soluble vitamin can be found in many animal products and fortified foods, including:
  • Beef liver
  • Clams
  • Eggs
  • Fish
  • Meat
  • Milk
  • Nutritional yeasts
  • Poultry
  • Breakfast cereals
It may also be taken as a supplement in the form of methyl-cobalamin or cyano-cobalamin.

How do the symptoms of B12 deficiency mimic dementia?

A person with B12 deficiency may exhibit the following physical and mental symptoms, as outlined by Johns Hopkins Medicine:
  • Confusion
  • Constipation
  • Depression
  • Fatigue
  • Memory loss
  • Poor balance
  • Soreness of the mouth or tongue
  • Tingling or numbness of the hands and feet
  • Weakness
  • Weight loss
You may hear people mention “B12 dementia,” but, in reality, it’s possible that the symptoms of B12 deficiency are just mimicking the symptoms of dementia. Some symptoms of B12 deficiency clearly overlap with dementia symptoms, including confusion, memory loss, and problems with balance and movement.

Are older adults more likely to have B12 deficiency?

Most Americans consume enough B12 in their diets to avoid a deficiency. However, older adults may be more likely to have a B12 deficiency, as noted by the NIH. B12 deficiency is especially prevalent among older adults with atrophic gastritis, an autoimmune disease relating to chronic inflammation in the stomach.
“Many older adults don’t have enough hydrochloric acid in their stomach to absorb the vitamin B12 that’s naturally present in food,” the NIH explains.
This deficiency may be more common among older adults who eat vegetarian or vegan diets because the main food sources of B12 are animal products.

Are B12 and dementia connected?

B12 deficiency and dementia may be connected, but the available clinical research is limited. The B12 deficiency and dementia connection has even been described as “controversial,” as noted in a 2021 study by Stanford University.
A large number of studies in peer-reviewed medical journals associate low B12 with poor cognitive function. And their findings raise interesting questions on what the brain needs to function properly. However, many studies also indicate that “low blood levels of vitamin B12 don’t affect cognitive decline in older people, regardless of whether they have dementia or Alzheimer’s disease,” as outlined by the NIH.
The decline in cognitive function associated with B12 deficiency does not appear to be the same as the type found in Alzheimer’s or other commonly understood forms of dementia, which could be why the research is conflicted.

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What do you need to know about B12 and dementia?

With many conflicting or inconclusive studies on the connection between B12 and dementia, it is clear that further research needs to be conducted.
It’s important to have a medical professional address a suspected B12 deficiency as soon as possible. Whether or not there’s a proven connection between B12 and dementia, this deficiency may cause damage to the nervous system, leading to an array of health problems. B12 also has an important role in energy production, as cells in the body require B12 to function properly. That said, B12 deficiencies may have a cascade of negative effects throughout the body.
It’s important to note that symptoms of this deficiency can take years to appear. This is because your body stores B12 as you consume it, amounting to about “1,000 to 2,000 times as much vitamin B12 as you’d typically eat in a day,” as noted by the NIH.

What steps can you take if you suspect B12 deficiency or dementia?

Regardless of the connection between B12 and dementia, you should always contact your medical team if you suspect that you or your loved one has a vitamin B12 deficiency or dementia-like symptoms.
Your medical care team will likely review you or your loved one’s medical history and current symptoms. Additionally, they may want to look at a comprehensive medication list as certain medicines, such as proton pump inhibitors and metformin, may interfere with the absorption of B12.
Following these initial evaluations, a medical professional may order blood work or other testing to determine what is causing symptoms and how to help you or your loved one.
Arendt, J. F., Horvath-Puho, E., Sorensen, H. T., Nexo, E., Pedersen, L., Ording, A. G., & Henderson, V. W. (2021). Plasma vitamin B12 levels, high-dose vitamin B12 treatment, and risk of dementiaThe Journal of Alzheimer’s Disease.
Bailey, R. L., Jun, S., Murphy, L., Green, R., Gahche, J. J., Dwyer, J. T., Potischman, N., McCabe, G. P., & Miller, J. W. (2020, December 10). High folic acid or folate combined with low vitamin B-12 status: potential but inconsistent association with cognitive function in a nationally representative cross-sectional sample of US older adultsThe American Journal of Clinical Nutrition.
Dangour, A. D., Allen, E., Clarke, R., Elbourne, D., Fletcher, A. E., Letley, L., Richards, M., Whyte, K., Uauy, R., & Mills, K. (2015, September). Effects of vitamin B-12 supplementation on neurologic and cognitive function in older people: a randomized controlled trialThe American Journal of Clinical Nutrition.

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Horvat, P., Gardiner, J., Kubinova, R., Pajak, A., Tamosiunas, A., Schöttker, B., Pikhart, H., Peasey, A., Jansen, E., & Bobak, M. (2016, April). Serum folate, vitamin B-12 and cognitive function in middle and older age: The HAPIEE studyExperimental Gerontology.
Johns Hopkins Medicine. (2020, October 10). Vitamin B-12.
Kabisch, M., Ruckes, C., Seibert-Grafe, M., & Blettner, M. (2011, September). Randomized controlled trials: Part 17 of a series on evaluation of scientific publicationsDeutsches Arzteblatt International.
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National Institute on Aging. What is dementia?
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Meet the Author
Melissa Lee

Melissa Lee is a copywriter at OurParents, where she primarily creates content for veterans and caregivers. She pairs over a decade of writing experience with expertise gained from her time as a military programs volunteer and military spouse. She studied journalism at the University of Kansas.

Edited byMarlena Gates

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