Key Takeaways

Dementia affects nearly one in 10 older adults in the United States, impacting countless families.

New research suggests that common infections may increase the risk of dementia later in life, raising questions about how infections contribute to cognitive decline and what can be done to mitigate this risk.

The study, published inNature Aging, analyzed data from 982 participants in the Baltimore Longitudinal Study of Aging. Researchers tracked the participants’ brain volumes and infection histories and found that six infections were associated with greater brain volume loss compared to those without these infections.

Influenza, herpes viruses, upper and lower respiratory tract infections, skin infections, and miscellaneous viral infections are among the infections linked to increased dementia risk. Flu and herpes infections showed specific links to brain volume loss in the temporal lobe, which is crucial for memory.

Those who had a history of infections also showed changes in 260 immune-related proteins, with 35 specifically linked to changes in brain volume.

Why Might Common Infections Increase Dementia Risk?

This isn’t the first study to tie infections to dementia risk.

A 2023 study published inJAMAfound that people hospitalized with an infection were 1.7 times more likely to be diagnosed with dementia compared to those without severe infections. Similar findings were reported in a 2021 study.

Other research suggests an indirect link, showing that getting vaccinated against the flu and shingles may lower the risk of developing dementia.

“It has long been known that infections have been associated with increased risk of dementia, especially coming to light over the last few years, with the advent of COVID infections and its long-term effects on the brain,” saidJasmin Dao, MD, PhD, a neurologist at Miller Children’s & Women’s Hospital Long Beach and MemorialCare Long Beach Medical Center. “However, mechanisms for how this occurs remain unclear.”

Dao called the new study “groundbreaking” because it highlights potential molecular pathways for how this link works.

There are several reasons infection may increase dementia risk. Severe infections may lead to prolonged hospitalizations, sepsis, and delirium, which may increase the risk of cognitive decline, Dao said. They can also trigger a systemic inflammatory and immune response in the body, which has the potential to impact brain health.

“Studies have found that a variety of infections are associated with cognitive decline, but it is more common in though those requiring hospitalization for their infection,” Dao said. “A mild infection may not trigger as great of an inflammatory or immune response that would affect protein expression leading to neurodegeneration.”

Can Vaccinations Lower the Risk of Dementia?

It’s currently unclear if staying up to date on vaccines can prevent dementia. However, routine vaccinations can help avoid severe illnesses from common infections.

“The expectation that vaccinations will help avoid chronic infections is reasonable, and avoiding infections is healthy for everyone, independent of their age,” saidClifford Segil, DO, a neurologist at Providence Saint John’s Health Center in Santa Monica, CA.

Severe infections may cause “collateral damage” to brain cells, saidThomas Russo, MD,a professor and chief of infectious disease at the University at Buffalo in New York. Therefore, getting the recommended vaccines is important for preserving your overall health.

If severe infections do raise the risk of dementia, “getting vaccinated would be a value-added benefit,” Russo said.

Even Household Chores May Reduce Your Dementia Risk

What This Means For YouResearch increasingly suggests that infections may impact long-term brain health, contributing to dementia risk. Staying current on recommended vaccinations can help reduce the chance of severe infections, which may lower your risk of associated cognitive decline.

What This Means For You

Research increasingly suggests that infections may impact long-term brain health, contributing to dementia risk. Staying current on recommended vaccinations can help reduce the chance of severe infections, which may lower your risk of associated cognitive decline.

6 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Manly JJ, Jones RN, Langa KM, et al.Estimating the Prevalence of Dementia and Mild Cognitive Impairment in the US: The 2016 Health and Retirement Study Harmonized Cognitive Assessment Protocol Project.JAMA Neurology.2022. DOI: 10.1001/jamaneurol.2022.3543Duggan MR, Peng Z, Sipilä PN, et al.Proteomics identifies potential immunological drivers of postinfection brain atrophy and cognitive decline.Nat Aging. 2024;4(9):1263-1278. doi:10.1038/s43587-024-00682-4Sipilä PN, Heikkilä N, et al.Hospital-treated infectious diseases and the risk of dementia: a large, multicohort, observational study with a replication cohort. Lancet Infect Diseases. 2021. DOI: 10.1016/S1473-3099(21)00144-4Bohn B, Lutsey PL, Misialek JR, et al.Incidence of dementia following hospitalization with infection among adults in the Atherosclerosis Risk in Communities (ARIC) study cohort.JAMA Netw Open. 2023;6(1):e2250126. doi:10.1001/jamanetworkopen.2022.50126Taquet, M., Dercon, Q., Todd, J.A.et al.The recombinant shingles vaccine is associated with lower risk of dementia.Nature Medicine,DOI: 10.1038/s41591-024-03201-5Harris K, Ling Y, Bukhbinder AS, et al.The impact of routine vaccinations on Alzheimer’s disease risk in persons 65 years and older: a claims-based cohort study using propensity score matching.J Alzheimers Dis. 2023;95(2):703-718. doi:10.3233/JAD-221231

6 Sources

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Manly JJ, Jones RN, Langa KM, et al.Estimating the Prevalence of Dementia and Mild Cognitive Impairment in the US: The 2016 Health and Retirement Study Harmonized Cognitive Assessment Protocol Project.JAMA Neurology.2022. DOI: 10.1001/jamaneurol.2022.3543Duggan MR, Peng Z, Sipilä PN, et al.Proteomics identifies potential immunological drivers of postinfection brain atrophy and cognitive decline.Nat Aging. 2024;4(9):1263-1278. doi:10.1038/s43587-024-00682-4Sipilä PN, Heikkilä N, et al.Hospital-treated infectious diseases and the risk of dementia: a large, multicohort, observational study with a replication cohort. Lancet Infect Diseases. 2021. DOI: 10.1016/S1473-3099(21)00144-4Bohn B, Lutsey PL, Misialek JR, et al.Incidence of dementia following hospitalization with infection among adults in the Atherosclerosis Risk in Communities (ARIC) study cohort.JAMA Netw Open. 2023;6(1):e2250126. doi:10.1001/jamanetworkopen.2022.50126Taquet, M., Dercon, Q., Todd, J.A.et al.The recombinant shingles vaccine is associated with lower risk of dementia.Nature Medicine,DOI: 10.1038/s41591-024-03201-5Harris K, Ling Y, Bukhbinder AS, et al.The impact of routine vaccinations on Alzheimer’s disease risk in persons 65 years and older: a claims-based cohort study using propensity score matching.J Alzheimers Dis. 2023;95(2):703-718. doi:10.3233/JAD-221231

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

Manly JJ, Jones RN, Langa KM, et al.Estimating the Prevalence of Dementia and Mild Cognitive Impairment in the US: The 2016 Health and Retirement Study Harmonized Cognitive Assessment Protocol Project.JAMA Neurology.2022. DOI: 10.1001/jamaneurol.2022.3543Duggan MR, Peng Z, Sipilä PN, et al.Proteomics identifies potential immunological drivers of postinfection brain atrophy and cognitive decline.Nat Aging. 2024;4(9):1263-1278. doi:10.1038/s43587-024-00682-4Sipilä PN, Heikkilä N, et al.Hospital-treated infectious diseases and the risk of dementia: a large, multicohort, observational study with a replication cohort. Lancet Infect Diseases. 2021. DOI: 10.1016/S1473-3099(21)00144-4Bohn B, Lutsey PL, Misialek JR, et al.Incidence of dementia following hospitalization with infection among adults in the Atherosclerosis Risk in Communities (ARIC) study cohort.JAMA Netw Open. 2023;6(1):e2250126. doi:10.1001/jamanetworkopen.2022.50126Taquet, M., Dercon, Q., Todd, J.A.et al.The recombinant shingles vaccine is associated with lower risk of dementia.Nature Medicine,DOI: 10.1038/s41591-024-03201-5Harris K, Ling Y, Bukhbinder AS, et al.The impact of routine vaccinations on Alzheimer’s disease risk in persons 65 years and older: a claims-based cohort study using propensity score matching.J Alzheimers Dis. 2023;95(2):703-718. doi:10.3233/JAD-221231

Manly JJ, Jones RN, Langa KM, et al.Estimating the Prevalence of Dementia and Mild Cognitive Impairment in the US: The 2016 Health and Retirement Study Harmonized Cognitive Assessment Protocol Project.JAMA Neurology.2022. DOI: 10.1001/jamaneurol.2022.3543

Duggan MR, Peng Z, Sipilä PN, et al.Proteomics identifies potential immunological drivers of postinfection brain atrophy and cognitive decline.Nat Aging. 2024;4(9):1263-1278. doi:10.1038/s43587-024-00682-4

Sipilä PN, Heikkilä N, et al.Hospital-treated infectious diseases and the risk of dementia: a large, multicohort, observational study with a replication cohort. Lancet Infect Diseases. 2021. DOI: 10.1016/S1473-3099(21)00144-4

Bohn B, Lutsey PL, Misialek JR, et al.Incidence of dementia following hospitalization with infection among adults in the Atherosclerosis Risk in Communities (ARIC) study cohort.JAMA Netw Open. 2023;6(1):e2250126. doi:10.1001/jamanetworkopen.2022.50126

Taquet, M., Dercon, Q., Todd, J.A.et al.The recombinant shingles vaccine is associated with lower risk of dementia.Nature Medicine,DOI: 10.1038/s41591-024-03201-5

Harris K, Ling Y, Bukhbinder AS, et al.The impact of routine vaccinations on Alzheimer’s disease risk in persons 65 years and older: a claims-based cohort study using propensity score matching.J Alzheimers Dis. 2023;95(2):703-718. doi:10.3233/JAD-221231

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