A common stomach infection is linked to lower IQ scores in kids

If you or your child has ever tested positive for H. pylori (a common stomach bacterium best known for causing ulcers), this study gives you a new reason to take it seriously beyond digestive symptoms: kids who carried the infection into their school years scored measurably lower on IQ tests than kids who didn't, even after researchers accounted for income, nutrition, and other confounders.

Key takeaways:

• Children infected with H. pylori (a stomach bacterium) at age 10-12 scored 5.9 to 7.5 points lower on full-scale IQ tests than uninfected children, a gap that held up after adjusting for socioeconomic status and nutrition.
• Kids who carried the infection continuously from infancy through school age had the lowest scores of any group.
• This is one observational cohort in Israel, not a clinical trial, so it shows an association, not a proven cause.
• H. pylori is common worldwide, especially where crowding and limited sanitation make childhood transmission likely, which is part of why researchers are watching this connection.

H. pylori infection at school age tracked with lower IQ scores in a 10-year cohort

Researchers led by Khitam Muhsen at Tel Aviv University followed 233 infants from Arab towns in Israel, testing 134 of them again at ages 10 to 12 for both H. pylori infection (found via a stool antigen test) and cognitive function, using the Wechsler Intelligence Scale for Children (WISC-IV), the standard clinical IQ test for this age group. Of the 134 kids followed to school age, 81 (60.4%) tested positive for H. pylori. Compared to the uninfected group, infected kids with milder markers of stomach inflammation scored 7.5 points lower on full-scale IQ (95% confidence interval: -12.7 to -2.2), and infected kids with more severe inflammation markers scored 5.9 points lower (95% CI: -11.7 to -0.01). Both gaps held after the researchers statistically adjusted for socioeconomic status, growth history, and markers of systemic inflammation, and the pattern repeated for verbal comprehension and working memory subscores specifically.

The finding is most relevant to families in regions where H. pylori spreads easily in early childhood

H. pylori infection is typically picked up in early childhood and, without treatment, tends to persist for life; it spreads more easily where households are crowded or clean water access is limited, which is why global infection rates in children run highest in lower-income regions. For parents managing a child's recurring stomach pain, ulcers, or a positive H. pylori test, this study adds a new consideration beyond digestive health: the kids in this cohort who stayed infected from infancy all the way through school age had the lowest cognitive scores of any group studied, suggesting duration of infection, not just a positive test at one point in time, may matter.

A decade of follow-up on the same children, not a one-time snapshot

This is a prospective cohort study, meaning the same children were tracked over roughly a decade rather than compared at a single point in time. Researchers tested for H. pylori in infancy and again at age 10-12 using stool antigen assays, and estimated gastric inflammation severity from a blood test (the ratio of two stomach-related proteins, pepsinogen I and II). They then ran statistical models adjusting for socioeconomic status, nutritional markers, and inflammation, and separately re-ran the analysis using a weighting technique designed to correct for kids who dropped out of the original cohort before follow-up. Both approaches produced a similar IQ gap, which is a meaningfully more rigorous design than a single cross-sectional comparison would offer.

What this could mean for a family managing a child's H. pylori diagnosis

This study doesn't tell parents to expect a specific IQ drop in an infected child, and it isn't a reason to panic over a routine positive test. What it does support is treating a child's H. pylori infection, and especially a persistent one that isn't cleared, as worth discussing with a pediatrician beyond just stomach symptoms, since the researchers found the strongest cognitive gap in kids infected continuously from infancy onward. Whether treating or eradicating the infection earlier in life would prevent any cognitive effect is a separate question this study wasn't designed to answer.

What's still unclear: it's one cohort, and the inflammation pattern didn't fully make sense

This is a single-cohort observational study, so it shows a statistical association, not proof that H. pylori itself causes lower cognitive scores; something else common to infected households (nutrition, other infections, or social factors the researchers didn't measure) could still be involved, even after their adjustments. The researchers also found that milder inflammation markers were tied to a numerically larger IQ gap than more severe inflammation, the opposite of what a straightforward "more inflammation, worse outcome" story would predict, and the paper doesn't fully explain why. The sample size (81 infected, 53 uninfected children at follow-up) is also modest for detecting IQ differences reliably.

What comes next

The authors call for their finding to be confirmed in other populations and larger samples before it's treated as established. They note most prior H. pylori-cognition research has focused on adults, so replicating this specific childhood pattern, and testing whether treating the infection changes the outcome, are the natural next steps, though the study gives no timeline for that follow-up work.

Common Questions

Does having H. pylori mean my child will have a lower IQ? No. This study found a group-level statistical association in one cohort, not a guaranteed individual outcome, and it doesn't prove the bacteria directly causes cognitive changes.

What is H. pylori? It's a bacterium that lives in the stomach lining, best known for causing ulcers and increasing stomach cancer risk; it's usually picked up in early childhood and can persist for life without treatment.

Should I get my child tested or treated for H. pylori because of this study? That's a conversation for your pediatrician. This study didn't test whether treating the infection reverses or prevents any cognitive effect, so it isn't grounds for a new treatment decision on its own.

Why did milder inflammation show a bigger IQ gap than severe inflammation? The researchers don't fully explain this reversal; it's one of the study's open questions and a reason the finding needs replication.

References

1. Bar Koren, Shubham Mathur, Ashraf Akawi, et al. (2026). The association of Helicobacter pylori infection and inflammation with cognitive development in preadolescents. Pediatrics & Neonatology. https://doi.org/10.1016/j.pedneo.2026.02.011
2. The association between H. pylori infection and cognitive deterioration: a systematic review and meta-analysis. NIH. https://pmc.ncbi.nlm.nih.gov/articles/PMC12439406/
3. Khitam Muhsen, Asher Ornoy, Ashraf Akawi, Gershon Alpert, Dani Cohen (2011). An association between Helicobacter pylori infection and cognitive function in children at early school age: a community-based study. BMC Pediatrics. https://doi.org/10.1186/1471-2431-11-43