Common stomach bug may increase risk of Alzheimer’s

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A common stomach bug may increase the risk of developing Alzheimer’s disease, a new study has suggested.

Researchers at McGill University in Montreal studied the health records of four million Britons aged 50 and above between 1988 and 2019.

They found that people with symptomatic Helicobacter pylori had an 11 per cent higher risk of developing Alzheimer’s disease - the most common type of dementia.

Helicobacter pylori is a bacterium that is found in contaminated food, water and soil, and can also be easily passed from person to person via bodily fluids.

Around 40 per cent of people in the UK have the bacterium in their stomach however, and it does not cause problems for the majority of people.

But approximately 15 per cent of people will have a symptomatic infection which can also trigger indigestion, gastritis, ulcers, and even stomach cancer.

The increased risk of developing Alzheimer’s peaked at 24 per cent, between seven and 10 years after an infection with the bacterium, before dropping off again.

The researchers suggested several ways the bacterium may travel to the brain and cause inflammation of cells and neurodegeneration.

They said the bacterium may also cause an imbalance in the gut and result in the overproduction of amyloid - the protein that clumps together and becomes plaques in the brain for Alzheimer’s patients.

The team also suggested that damage to the stomach’s membrane by the infection may affect the absorption of vitamin B12 and iron - a deficit in both is associated with dementia.

With this new research, they suggest eradicating the bug could help prevent about 200,000 cases of Alzheimer’s globally each year.

In Britain alone, there are estimated to be 944,000 people living with dementia, with the majority suffering from Alzheimer’s.

In 2022, dementia and Alzheimer’s disease were the leading cause of death in England and Wales.

“Given the global ageing population, dementia numbers are expected to triple in the next 40 years. However, there remains a lack of effective treatment options for this disease,” said Dr Paul Brassard, the study’s senior author and a professor in McGill’s department of medicine.

“We hope the findings from this investigation will provide insight on the potential role of H. pylori in dementia in order to inform the development of prevention strategies, such as individualised eradication programs, to reduce infections at the population level.”

The study was published in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association.