Eye-dwelling bacteria linked to Alzheimer's risk could aid early detection

A Nature Communications study found higher levels of the bacterium Chlamydia pneumoniae in retinal tissue of people with Alzheimer's disease, with greater bacterial burden associated with more severe cognitive decline. The findings, supported by lab and mouse models, suggest retinal infection and inflammation may reflect brain pathology and that APOE4 carriers had higher retinal bacterial levels, pointing to retinal imaging as a potential noninvasive biomarker and possible infection-targeted therapies.