A study of more than 53,000 adults in Wales has found a link between severe bloodstream infections and a higher risk of developing dementia. Researchers tracked individuals for up to 10 years after they experienced a bloodstream infection, where bacteria enter the bloodstream directly. They compared them to a matched group of people who never had such an infection.
The findings show that people who had a bloodstream infection developed dementia at a higher rate over the following decade. Ten years after the infection, there were about 160 additional dementia cases per 1,000 people in the infected group compared to those without an infection. This increase was not seen among people hospitalized for knee replacement surgery, which suggests the higher risk was not simply due to being in the hospital or having a major medical event.
The study drew from a population of 2.5 million people in Wales. Researchers identified 26,792 individuals with a confirmed bloodstream infection and matched them one-to-one with people who had not had one. Both groups were followed for up to 10 years to see who developed dementia.
Bloodstream infections are known to cause short-term cognitive effects like delirium, but their long-term impact on brain health has not been studied as much. The researchers did observe a small increase in lung cancer risk after bloodstream infections, which suggests some other factors may still be at play. However, that increase was much smaller than the dementia link, indicating it likely does not fully explain the findings.
Possible reasons for the link
The study does not prove that infections cause dementia. It shows a connection, and the researchers say the signal is strong and the mechanism is plausible. Severe infections trigger inflammation, which may have lasting effects on brain health. The findings add to growing evidence that severe infections could be a risk factor for long-term cognitive decline.
Bloodstream infections are relatively uncommon, and most people who have one will not necessarily develop dementia. The study reinforces the idea that protecting overall health may also protect the brain. Preventing infections through everyday habits such as staying up to date on vaccines, practicing good hand hygiene, promptly treating infections, and managing chronic conditions may have benefits that go beyond short-term health.
Researchers say future studies should look into whether preventing or aggressively treating severe infections could become another way to reduce dementia risk. Dementia affects millions of people worldwide, and there are still no treatments that can stop or reverse the disease. This makes it important to find lifestyle and health factors that may lower risk.
This study is observational, meaning it shows a connection rather than direct cause and effect. But the findings suggest that bloodstream infections may be one of the more overlooked factors in long-term dementia risk. The research continues to build, and the results are worth knowing for anyone interested in brain health.
