Helicobacter pylori Eradication Treatments and Risk of Alzheimer Disease: A Case-Control Study Nested in the Finnish Population

Abstract

Background: Helicobacter pylori ( H. pylori ) has been inconsistently associated with the risk of Alzheimer disease. The exposure assessment period has often overlapped with the prodromal time of Alzheimer disease. Cognitive disorders might increase vulnerability to infectious pathogens, complicating the ascertainment of the temporal relationship between H. pylori infection and Alzheimer disease.

Methods: This Finnish nested case-control study included 70,520 persons with incident Alzheimer disease diagnosed between 2005 and 2011 and 281,233 age-, sex-, and region of residence-matched controls. We obtained information on comorbidities and drug use from the national healthcare registers. We identified dispensed H. pylori eradication treatments from the Prescription Register. We considered exposure at least 5 years before Alzheimer disease diagnosis in the main analysis. We compared the risk of Alzheimer disease between H. pylori eradication treatment users and nonusers using confounder-adjusted (comorbidities and other drug use) conditional logistic regression. We assessed cumulative exposure by calculating the number of eradication treatments.

Results: The prevalence of exposure to H. pylori eradication treatment at least 5 years before the outcome was 4.1% in cases and 3.9% in controls. The odds ratio (95% confidence interval) was 1.06 (1.02, 1.11) in the crude and 1.03 (0.99, 1.07) in the confounder-adjusted model. We observed no association between cumulative exposure and risk of Alzheimer disease.

Conclusion: Our results, reflecting diagnosed and treated H. pylori infection late in life, do not support the hypothesis of H. pylori as an independent risk factor for Alzheimer disease. The previously reported association may be explained by reverse association and confounding.

Keywords: Alzheimer disease; Case–control study; Confounding factors; Epidemiologic; Risk factors.