# Helicobacter pylori infection, atrophic gastritis, and disabling dementia: the Japan Public Health Center-based Prospective Study

## TL;DR

This study finds that Helicobacter pylori infection and atrophic gastritis may increase dementia risk, especially when vitamin B12 intake is low.

## Contribution

The study identifies a synergistic effect of H. pylori infection, atrophic gastritis, and low vitamin B12 intake on dementia risk.

## Key findings

- H. pylori infection and severe atrophic gastritis are linked to higher dementia risk in low vitamin B12 consumers.
- Combined H. pylori infection and AG increase dementia risk among individuals with low vitamin B12 intake.
- No significant association was found in individuals with higher vitamin B12 intake.

## Abstract

A meta-analysis reported a positive association between Helicobacter pylori (H. pylori) infection and dementia incidence. H. pylori infection leads to atrophic gastritis (AG) and affects the absorption of nutrients needed for nerve growth, such as vitamin B12 and folate. We aimed to clarify the associations of H. pylori IgG titer, AG, and their combination with disabling dementia incidence and to examine the interaction with vitamin B12 and folate.

Anti-H. pylori immunoglobulin G (IgG) titer and pepsinogen levels were measured in 6,817 participants in 1993 (40–69 years), and the incidence of disabling dementia was followed during a median follow-up of 11.0 years. Associations of anti-H. pylori IgG titer, AG, and their combination with disabling dementia were examined using a multivariable-adjusted Cox proportional hazard model, with stratified analyses by dietary intake of vitamin B12 and folate.

1,325 (19.4%) developed disabling dementia during the follow-up period from 2006 to 2016. Among participants with low vitamin B12 intake, H. pylori infection and severe AG were positively associated with the risk of disabling dementia, with HRs of 1.26 (95% CI: 1.01–1.58) for H. pylori infection (H. pylori IgG titer ≥10 U/mL) and 1.34 (95% CI: 1.06–1.68) for severe AG. Additionally, having both H. pylori infection and AG was associated with an increased risk of dementia among individuals consuming less vitamin B12 than the median (HR 1.30, 95% CI: 1.05–1.61), compared with H. pylori-seronegative and AG-negative.

The combination of H. pylori infection, subsequent AG, and low vitamin B12 intake may be related to increased risk of dementia.

The online version contains supplementary material available at https://doi.org/10.1265/ehpm.25-00228.