Viral infection and dementia risk: A systematic bidirectional Mendelian randomization analysis.

Publication date: Aug 21, 2026

Viral infections have attracted increasing interest as potentially alterable risk factors for dementia; nonetheless, the results from observational research are variable and prone to confounding bias and reverse causation. This work seeks to systematically explore the potential causal associations between several viral infections and various forms of dementia by a Mendelian randomization methodology utilizing summary statistics and extensive genomic data from the Finnish FinnGen R12 database. This study initially included 14 viral infections, including anogenital herpes, infectious mononucleosis, acute hepatitis B, herpesviral infections, acute poliomyelitis, rubella, varicella, viral warts, herpes zoster, COVID-19, measles, mumps, acute hepatitis A, and HIV infection. The outcome measurements included 15 forms of dementia, including Alzheimer’s dementia, vascular dementia and its subtypes, and frontotemporal dementia. The principal analysis utilized the inverse variance weighted (IVW) methodology. This report provides the number of SNPs in each analysis, the mean F statistic, the causal effect estimates, and their 95% confidence ranges. All the MR-Egger regression, weighted median, simple mode, and weighted mode approaches were used in the sensitivity analyses. The final analysis omitted acute hepatitis A, HIV infection, and measles because of inadequate instrumental variables (only 1-2 SNPs). The IVW primary analysis revealed 6 associations with uncorrected P

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