Increased Alzheimer’s Disease after Symptomatic Helicobacter Infection

Large study by Charité in Berlin and McGill University in Montreal quantifies correlation

As the population ages, an increase in dementia is expected. Current forecasts predict that the incidence of dementia is likely to triple over the next four decades. Given that a cure for dementia is not yet in sight, research efforts are also focused on identifying risk factors in the hope of effectively combating them.

One of these potential risk factors is the stomach germ Helicobacter pylori (Hp), which has been the subject of scientific research for some time. According to a report published by Charité – Universitätsmedizin Berlin on December 13, 2023, around a third of the population is infected with this bacterium.

Although an infection with Helicobacter pylori (Hp) often remains asymptomatic, it can have serious consequences, including gastritis and, in severe cases, gastric cancer. In addition, numerous laboratory studies indicate a link between Hp infection and effects on the central nervous system. Professor Antonios Douros, a pharmacoepidemiologist at Charité, explains that the bacterium can reach the brain in various ways, potentially causing inflammation, damage and neuronal degeneration. Another important aspect is that stomach tissue damaged by the germ can impair the absorption of vitamin B12 and iron. This nutrient deficiency could also increase the risk of dementia.

Four million people studied over a long observation period

The link between Helicobacter pylori infection and Alzheimer’s disease has already been investigated in numerous studies. However, many of these studies had methodological shortcomings, such as an insufficient number of subjects, which made it difficult to reliably assess the strength of this association. Due to these limitations, the exact nature of the relationship between Hp infection and the development of Alzheimer’s dementia has remained unclear.

The study by Antonios Douros and Professor Paul Brassard from McGill University in Montreal, Canada, in collaboration with other colleagues, has now overcome important methodological weaknesses of previous studies. Their research, which was published in the online edition of “Alzheimer’s & Dementia” on December 13, 2023, includes a large sample of over four million people and also takes into account the time lag between an Hp infection and a possible increase in the risk of Alzheimer’s disease. By analyzing electronic patient records from the UK, the team was able to quantify the link between an infection with the stomach germ Helicobacter pylori and the development of Alzheimer’s dementia over the course of a lifetime.

Alzheimer’s risk increases by 11 percent after infection, and by as much as 24 percent after ten years

Is infection with Helicobacter pylori (Hp) a modifiable risk factor for Alzheimer’s dementia? In this comprehensive study of 4,262,092 people who did not have dementia at the start of the study, 40,455 of them developed Alzheimer’s disease after an average of eleven years. The researchers analyzed data collected from 1988 to 2017 to determine the relative risk of Alzheimer’s disease in people over the age of 50 with symptomatic Hp infection compared to people without symptomatic Hp infection after the age of 50. The results show that the risk of Alzheimer’s disease in people over 50 increases by an average of 11 percent after a symptomatic Hp infection and can even be increased by 24 percent around ten years after the infection. However, according to the researchers, this does not mean that every person will inevitably develop Alzheimer’s after a symptomatic Hp infection. The calculations are an increase in the relative risk compared to people who have not had a symptomatic Hp infection after the age of 50.

“For us, this result confirms the assumption that Helicobacter pylori infection could be an influenceable risk factor for Alzheimer’s dementia,” says first author Antonios Douros. The question of whether and to what extent a systematic and far-reaching fight against the stomach germ Helicobacter pylori through eradication programs could actually have an influence on the development of Alzheimer’s disease has yet to be answered. Answering this question requires large-scale randomized studies in order to reliably evaluate the effectiveness of such measures.