More than 53,000 adults in Wales took part in a study that found a link between severe bloodstream infections and a higher risk of developing dementia later in life.
Researchers identified nearly 27,000 people who had a confirmed bloodstream infection and matched them with a similar number of people who had not. Both groups were followed for up to 10 years to track who developed dementia.
People who had a bloodstream infection developed dementia at a higher rate than those who did not. Ten years after the infection, there were about 160 additional dementia cases per 1,000 people in the infected group compared to the uninfected group. The same increase was not seen in people who had knee replacement surgery, which suggests the risk is not simply due to being hospitalized or having a major medical event.
The study found a small increase in lung cancer risk after bloodstream infections, but that increase was much smaller than the link to dementia. This indicates that other factors may play a role, but they likely do not explain the full connection.
Bloodstream infections are already known to cause short-term cognitive effects such as delirium. Their long-term impact on brain health has been less studied. The findings add to growing evidence that severe infections and the inflammation they cause may have lasting effects on the brain.
The study does not prove that infections cause dementia. It shows a connection, not direct cause and effect. Bloodstream infections are relatively uncommon, and most people who have one will not develop dementia.
The findings suggest that preventing infections through everyday habits may have benefits for brain health. Staying up to date on vaccines, practicing good hand hygiene, treating infections promptly, and managing chronic conditions are all steps that may help reduce risk.
Researchers say future studies should look at whether preventing or aggressively treating severe infections could become a strategy for lowering dementia risk. The link between bloodstream infections and dementia is strong, and the mechanism is plausible. This factor may be one of the more overlooked in long-term dementia risk.
Dementia affects millions of people worldwide. There are still no treatments that can stop or reverse the disease. Researchers continue to search for lifestyle and health factors that may lower risk. This study points to one factor that often goes unnoticed.
