A new study published in Volume 17, Issue 10 of Aging-US on 13 October 2025 offers compelling evidence that hospitalisation for infections may play a significant role in increasing long-term dementia risk. The paper, titled “Hospitalization with infections and risk of Dementia: a systematic review and meta-analysis,” brings together the most extensive collection of research yet assembled on this topic. Led by first author Wei Yu Chua of the National University of Singapore and corresponding author Eng-King Tan of the National Neuroscience Institute and Duke-NUS Medical School, the study delivers one of the clearest examinations to date of how serious infections intersect with cognitive decline in later life.
The researchers began by screening approximately 1,900 studies, eventually narrowing their analysis to 16 high-quality studies involving a total of 4,266,276 individuals. This immense dataset allowed for a far more precise understanding of the association between infection-related hospital stays and subsequent brain health. Their findings indicate that adults hospitalised for infections face an 83% higher risk of developing all-cause dementia than those who were never admitted for similar reasons. Among the infections examined, sepsis was linked to the greatest increase in risk, followed by pneumonia, urinary tract infections, and skin or soft-tissue infections. In terms of dementia subtypes, vascular dementia showed a notably stronger association with infection history than Alzheimer’s disease.
One of the study’s central insights concerns the role of systemic inflammation. Infections trigger widespread immune activity, and inflammatory molecules can sometimes penetrate the blood–brain barrier. Once in the brain, they may contribute to the accumulation of harmful proteins or accelerate neuronal damage, especially in older adults whose immune responses tend to recover more slowly. The analysis suggests that even a single hospitalisation for infection may set in motion processes that hasten cognitive decline, particularly in people already at heightened risk due to age or underlying health conditions.
The timing of dementia onset following infection appears to be particularly significant. The researchers found that the risk is highest during the first year after hospital discharge, indicating a period of increased vulnerability. However, the elevated risk persists well beyond this initial phase. Studies that followed participants for more than ten years showed even stronger links, suggesting that the effects of severe infection may cast a long shadow over later cognitive health. These results underline the value of early cognitive monitoring and long-term follow-up for older adults recovering from primary infections.
The implications of this research extend well beyond clinical settings. As global populations continue to age, infections are becoming an increasingly common reason for hospital admission. With over 50 million people living with dementia worldwide and annual care costs in the United States alone exceeding USD 300 billion, understanding preventable or modifiable risk factors is crucial. By highlighting the potential cognitive consequences of infection-related hospitalisation, this study points to new avenues for early intervention, improved hospital care, and enhanced post-discharge monitoring to safeguard long-term brain health.
More information: Wei Yu Chua et al, Hospitalization with infections and risk of Dementia: a systematic review and meta-analysis, Aging-US. DOI: 10.18632/aging.206329
Journal information: Aging-US Provided by Impact Journals LLC
