A common stomach bug carried by two thirds of people may increase the risk of developing Alzheimer’s by up to 24%, according to a new study.
Helicobacter pylori infection often occurs in childhood, but most people do not realise they have it because it does not always cause sickness. The bacteria infects the lining of the stomach and upper small intestine, in some cases triggering indigestion, gastritis, ulcers or even stomach cancer.
It is usually spread through contact with bodily fluids, or contaminated food or water.
To determine whether the bacteria may also be linked to Alzheimer’s, researchers from McGill University in Montreal analysed the health data of more than 4 million people over 50 in the UK between 1988 and 2019.
They found those with a symptomatic infection – meaning it had damaged the lining of the digestive tract – had an 11% higher risk of developing Alzheimer’s, increasing to 24% a decade after initial infection.
However, scientists have been unable to determine exactly how the infection may cause the disease, but one possibility is that the bacteria travels through the damaged areas into the blood and up to the brain, where it can lead to inflammation and neurodegeneration.
Another mechanism may be caused by chronic infection disrupting the absorption of vitamin B12 and iron, both of which are associated with dementia.
Although there are thought to be many factors in the cause of Alzeheimer’s, the team said their results opens avenues for future research, particularly whether getting rid of the bacteria could effectively prevent the disease.
What is Alzheimer’s?
Alzheimer’s disease is the most common cause of dementia in the UK.
Dementia is the name for a group of symptoms associated with an ongoing decline of brain functioning. It can affect memory, thinking skills and other mental abilities.
Source: NHS
‘Given the global ageing population, dementia numbers are expected to triple in the next 40 years,’ said senior author Professor Paul Brassard. ‘However, there remains a lack of effective treatment options for this disease.
‘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 team noted that they couldn’t rule out whether asymptomatic infections – those without any symptoms – also increased the risk of Alzheimer’s.
The study is published in the journal Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association.
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