Common stomach bacteria Helicobacter pylori (H. pylori) are present in around half of the global population. People infected with the bacteria are often asymptomatic. When symptoms do occur, they are nonspecific and may include nausea, vomiting, and abdominal pain.
Researchers have long suspected a link between H. pylori and Alzheimer's disease. Studies show that the bacteria can reach the brain via various routes, where it may potentially cause inflammation and destruction of neurons. Other studies have also shown that structural damage in gastric mucosa caused by chronic H. pylori infection may affect the absorption of vitamin B12 and iron, deficits of which are linked to a higher dementia risk.
In the current study, researchers used healthcare data from the UK's Clinical Practice Research Datalink (UK CPRD). They included 4,262,092 subjects with an average age of 60.4 years old upon entry who were dementia-free. After a minimum follow-up of 2 years and a mean follow-up of 11 years, 40,455 developed Alzheimer's disease.
After analyzing the data, they found that symptomatic H. pylori infection after the age of 50 was linked to an 11% increased risk of Alzheimer's disease. They noted that this increased risk peaked at 24% around ten years after the initial infection and that results were similar for all ages and among men and women.
The researchers said the findings suggest H. pylori infection may be a modifiable risk factor for Alzheimer's disease. They noted, however, that it remains unknown whether eradicating the microbe may affect the development of Azheimer's and, if so, to what extent. Large-scale randomized studies are thus required to understand the practical implications of these findings.
Sources: Neuroscience News, Alzheimer's and Dementia