SEVERE infections are linked to a higher dementia risk, a 2026 Finnish study has found.
Researchers identified nearly 30 hospital-treated infections, including cystitis, tied to an increased dementia risk.
Severe Infection and Dementia Risk
It has previously been established that people who experience severe infections are at a higher risk of developing dementia.
However, it has been unclear as to whether the relevant association is due to comorbidities that predispose the patient to both infections and dementia.
Researchers found that severe infections are independently associated with a higher dementia risk.
Register-Based Finnish Study
Authors analysed more than 62,500 people aged 65 or older in Finland in 2016, who were diagnosed with late-onset dementia between 2017 and 2020.
They also included a control group of more than 312,700 participants without dementia, matched for year of birth, sex, and follow-up period.
Analyses were also adjusted for education, marital status, employment, and area of residence.
Researchers identified nearly 30 hospital-treated diseases that occurred 1–21 years before dementia diagnosis and were significantly associated with an approximately 20% higher risk of dementia.
Identified Diseases Tied to Higher Dementia Risk
Authors identified two relevant infectious diseases tied to heightened risk: cystitis and bacterial infection of an unspecified site.
Beyond infectious disease, 27 mental, behavioural, digestive, endocrine, cardiometabolic, neurological, and eye diseases, as well as injuries were similarly associated.
Almost half the people with dementia had at least one of the relevant diseases diagnosed before onset.
Notably, the associations of the two infectious diseases with increased dementia risk were not attributable to the 27 comorbid dementia-related diseases.
After adjustment for comorbidities, people with cystitis had a 22% higher chance of dementia.
People with bacterial infections at an unspecified site had a 19% increased risk.
Findings were comparable across sex and education subgroups, and the association was stronger in cases of early onset dementia, researchers reported.
Reference
Sipilä P N et al. The role of noninfectious comorbidities in the association between severe infections and risk of dementia in Finland: A nationwide registry study. PLoS Med. 2026;DOI:10.1371/journal.pmed.1004688.
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