US researchers found that levels of Chlamydia pneumoniae in the retina and cerebral cortex of Alzheimer’s dementia (AD) patients were elevated compared with controls. Published in Nature Communications, the study was led by Cedars-Sinai Medical Center researchers and analysed retinal and brain tissues from 104 donors – those with normal cognition, AD, or mild cognitive impairment (MCI) due to AD.

Their results support earlier studies linking C. pneumoniae infection to chronic inflammation and showing a five-fold increased AD risk in the presence of this pathogen. They also found infection was associated with activation of retinal NLRP3 inflammasomes aligning with AD pathology. They cited a large Taiwanese cohort found patients with C. pneumoniae-type pneumonia who received appropriate macrolide or fluoroquinolone therapy had a lower subsequent risk of AD versus inadequately treated cases, further supporting their findings.

They suggested infection-driven neuroinflammation and potential early intervention targets motivates exploration of NLRP3-attenuating or early antibiotic-based interventions.