Is it always aging factor that causes Alzheimer?

One study from 2019 found a strong link between Alzheimer's and a type of bacteria that causes gum disease. Scientists discovered this bacteria, called Porphyromonas gingivalis, in the brains of people who had Alzheimer's.

Nidarshana Sarma

Sep 09, 2025 14:51 IST

Alzheimer's disease might not just be a result of aging, but could be triggered by an infection. Photograph: (Jonathon Borba)

A growing number of scientific studies support a concerning idea: Alzheimer's disease might not just be a result of aging, but could be triggered by an infection.

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Researchers are still trying to understand how this infection works, but many studies suggest Alzheimer's is more complex than previously thought.

In experiments with mice, researchers found that infecting their mouths with this bacteria led to the bacteria spreading to their brains. This caused an increase in amyloid beta, a protein associated with Alzheimer's.

The researchers also found toxic enzymes, called gingipains, produced by the bacteria in the brains of Alzheimer's patients. These enzymes were linked to two markers of the disease: tau protein and ubiquitin.

What's significant is that these toxic enzymes were also found in the brains of people who didn't have Alzheimer's. This suggests that the bacteria might be involved in the early stages of the disease, before symptoms appear.

The research team tested a compound that reduced the bacteria's presence in the brains of mice, as well as reducing amyloid-beta production and inflammation.

While more research is needed, the scientific community is hopeful. "It's been over 15 years since new dementia treatments were developed, so it's crucial to explore all possible approaches," said David Reynolds from Alzheimer's Research.

The study's findings were published in Science Advances, and researchers are optimistic about the potential for new treatments.