Hospital infections associated with higher risk of dementia

BUFFALO, NY — November 25, 2025 — A new research paper was published in Volume 17, Issue 10 of Aging-US on October 13, 2025, titled “Hospitalization with infections and risk of Dementia: a systematic review and meta-analysis.”

This large-scale meta-analysis, led by first author Wei Yu Chua from the National University of Singapore and corresponding author Eng-King Tan from the National Neuroscience Institute and Duke-NUS Medical School in Singapore, shows that adults hospitalized with infections have a significantly higher risk of developing dementia. The findings are especially important as global populations grow older and hospitalizations for infections increase, highlighting a potential new approach for dementia prevention.

“Out of 1900 studies that were screened initially, 16 studies comprising 4,266,276 patients were included for analysis.” 

The researchers analyzed data from over 4 million individuals across 16 studies, making this study the most comprehensive review to date on the association between infection-related hospital stays and long-term brain health. The results showed that being hospitalized for an infection raised the risk of all-cause dementia by 83%. Among the types of infections studied, sepsis carried the highest risk, followed by pneumonia, urinary tract infections, and skin or soft tissue infections. The risk of developing vascular dementia was notably higher than that of Alzheimer’s disease.

One possible explanation for the association between infections and dementia is that infections trigger systemic inflammation that may reach the brain. Inflammatory molecules can cross the blood-brain barrier, potentially leading to the buildup of damaging proteins and the death of brain cells. This process may be more severe in older adults, whose immune systems are often slower to respond and recover. The study also suggests that even a single infection-related hospitalization can speed up cognitive decline, especially in individuals already at higher risk.

Importantly, the risk of dementia was greatest within the first year following an infection but remained elevated for many years afterward. In fact, studies with follow-ups longer than a decade showed even stronger associations. These results suggest the need for early cognitive monitoring after hospital discharge, particularly in older adults recovering from infections.

These findings have important implications for healthcare systems, particularly those serving aging populations, and underscore the lasting impact that infections can have on the brain. This research highlights the importance of looking beyond genetics and lifestyle for prevention strategies. With over 50 million people affected by dementia worldwide and annual care costs in the U.S. exceeding $300 billion, identifying new and preventable risk factors is critical. Reducing infections, improving hospital care, and monitoring brain health after illness may offer promising ways to protect cognitive function in aging populations.

DOI: https://doi.org/10.18632/aging.206329

Corresponding author: Eng-King Tan – tan.eng.king@singhealth.com.sg

Abstract video: https://www.youtube.com/watch?v=uyv5VHHHIA4

Keywords: aging, Alzheimer disease, Dementia, hospitalization, infections, meta-analysis

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