Common medical condition seen years before dementia develops, study reveals
New research has identified an association between late-onset dementia and certain infections.
The study, published in the journal PLOS Medicine, investigated the link between the two, exploring whether the connection could stem from other health issues stemming from severe infections.
Researchers at the University of Helsinki, Finland, considered 170 common hospital-treated diseases that occurred one to 21 years before diagnosis in more than 65,000 patients with dementia aged 65 and older.
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After narrowing the list down to 29 diseases showing the strongest link to dementia, two were infections – cystitis (a bacterial/urinary tract infection) and general bacterial infection.
The other diseases were non-infectious, including mental disorders as well as digestive, endocrine, cardiovascular and neurological diseases, as well as injuries.
Nearly half (47%) of dementia cases came after one of the 29 identified diseases.
Even after adjusting for these diseases, the link between dementia and infection remained intact, the researchers found. These infections typically occurred about five to 6-½ years before dementia diagnosis.
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Those with hospital-treated cystitis and bacterial infection, for example, had about a 19% higher rate of late-onset dementia.
Overall, the findings "support the possibility that severe infections increase dementia risk," the researchers concluded.
As the development of dementia often takes "years or even decades," the findings suggest that severe infections "might accelerate underlying cognitive decline," the study authors commented in a press release.
The lack of baseline cognitive assessment and clinical examination data before dementia diagnoses posed some limitations to the study. Infection treatment data was also not available.
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Study co-author Pyry N. Sipila, MD, PhD, a public health lecturer at the University of Helsinki, pointed out that the study was observational.
"Thus, we cannot prove whether there really is cause and effect between severe infections and dementia," he told Fox News Digital. "Ideally, there would be intervention trials in the future that would test whether the prevention of infections will help reduce or delay the onset of dementia."
Sipila recommends that adults stay up to date on vaccinations.
"Although our study does not prove that vaccinations would help prevent dementia, I think it certainly doesn’t hurt to have that one extra benefit of potentially reducing the risk," he said.
Dr. Joel Salinas, a Harvard-trained behavioral neurologist and chief medical officer at Isaac Health, said the study's size suggests it could be applied to other populations.
"We often assume infections are just a marker of someone being generally at risk of illness, but here, severe infections specifically appear to play an independent role," the New York-based expert, who was not involved in the study, told Fox News Digital.
"That suggests there may be something biologically meaningful happening, like inflammation or immune responses that affect the brain."
Salinas added that it's important to keep this increased risk "in perspective," as having an infection doesn't guarantee the development of dementia, but should be considered "one piece of a much larger puzzle."
Some of the strongest risk factors for dementia, according to Salinas, include fundamentals like heart disease, hypertension, diabetes, depression and head injuries.
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"What this study adds is a reminder that severe infections, especially those requiring hospitalization, may also be part of that risk profile, particularly in older adults," he told Fox News Digital.
"We’re moving away from thinking about dementia as a single disease with a single cause, and toward understanding it as the result of multiple interacting factors over time."