Infection with Stomach Bacteria May Increase Risk of Alzheimer’s Disease

Infection with the stomach bacterium Helicobacter pylori could increase the risk of developing Alzheimer’s disease: In people over the age of 50, the risk following a symptomatic infection can be an average of 11 percent higher, and even more about ten years after the infection, at 24 percent greater risk. 

These are the findings of a study by Charité — Universitätsmedizin Berlin and McGill University (Canada), now published in the journal Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association. The researchers analyzed three decades’ worth of patient data.

As today’s populations age, dementia is set to become more common, tripling in prevalence in the next 40 years. With no cure in sight so far, researchers are trying to pinpoint the risk factors involved in dementia, in hopes of specifically targeting those factors.

Researchers have long suspected Helicobacter pylori, a common gut microbe, of being a potential risk factor. Nearly one-third of all people in Germany are infected with this type of bacteria. An infection can be asymptomatic, but the bacteria can also cause inflammation of the stomach lining or even stomach cancer. 

When the stomach has been damaged by these microbes, it is also no longer able to absorb Vitamin B12 or iron effectively, which also increases the risk of dementia.

One outcome of this was that before now, it was also not possible to say just how strong a link there is between this type of bacterial infection and Alzheimer’s disease.

The researchers used data gleaned from electronic patient records in the UK to quantify the link between H. pylori and Alzheimer’s disease over the course of a person’s lifetime.

The calculations show an increase in the relative risk compared to people who did not experience a symptomatic H. pylori infection after the age of 50.


Antonios Douros, Zharmaine Ante, Carlo A. Fallone, Laurent Azoulay, Christel Renoux, Samy Suissa, Paul Brassard. Clinically apparent Helicobacter pylori infection and the risk of incident Alzheimer’s disease: A population‐based nested case‐control study. Alzheimer’s & Dementia, 2023; DOI: 10.1002/alz.13561

Charité – Universitätsmedizin Berlin. (2023, December 13). Infection with stomach bacteria may increase risk of Alzheimer’s disease. ScienceDaily. Retrieved December 14, 2023 from

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