Bacteria Linked to Sinusitis May Affect Alzheimer’s Disease
Recent research published in *Nature Communications* suggests that bacteria commonly associated with sinus infections and pneumonia might have a negative impact on Alzheimer’s disease. Researchers at Cedars-Sinai Health Sciences University in California found evidence of Chlamydia pneumoniae in the eyes of deceased patients who had Alzheimer’s.
“The retina is directly connected to the brain, essentially an extension of it,” noted the lead researcher, Maya Koronyo-Hamaoui, Ph.D., who works in neurosurgery, neurology, and biomedical sciences. This study indicates that the bacteria can invade retinal tissue, triggering inflammation that persists for years and can be tied to nerve cell death, potentially exacerbating cognitive decline and Alzheimer’s symptoms.
The findings suggest that infections should be treated early with antibiotics. Koronyo-Hamaoui stated that doctors should consider testing for Chlamydia pneumoniae when patients present symptoms of pneumonia or respiratory infections and prescribe appropriate antibiotics.
Study Overview
Investigators analyzed retinal tissues from over 100 deceased individuals, categorizing them into groups: Alzheimer’s patients, those with some cognitive impairment, and individuals with normal cognition. They employed advanced imaging and genetic testing and found that Alzheimer’s patients exhibited higher bacterial levels in both brain and retinal tissues.
Genetic Risk Factors
Koronyo-Hamaoui noted an increased presence of Chlamydia pneumoniae in individuals with the APOE4 genetic variant, a known Alzheimer’s risk factor. This bacterium seems to correlate with more significant cognitive decline. In lab mice with Alzheimer’s, exposure to C. pneumoniae was linked to heightened inflammation and neuronal cell death, further supporting its potential role in the disease development.
The infection was also linked to increased production of amyloid beta, a protein that accumulates in the brains of Alzheimer’s patients. The study hints at using the retina for diagnosing and monitoring the disease, though researchers agree that further investigation is necessary.
Expert Opinions
Dr. Aaron Glatt, chief of infectious diseases at Mount Sinai South Nassau, found the results intriguing but urged caution. He emphasized that the findings reveal an association rather than a cause-and-effect relationship. “This doesn’t mean that past infections lead to Alzheimer’s,” he pointed out. “Chlamydia pneumoniae is common, and while there’s a link identified, it doesn’t mean everyone exposed will develop the disease.”
Dr. Sharon Fekrat, a retinal specialist at Duke University, echoed this sentiment. She noted that while the results are promising for understanding how inflammation affects disease progression, they don’t suggest that infections are the direct cause of Alzheimer’s.
Future Applications
While some teams are working on developing retinal imaging for diagnostics, Fekrat cautioned that these methods are not yet standard practice. Experts advise focusing on established brain-healthy habits—managing cardiovascular risks, remaining socially and mentally active, and consulting healthcare providers when cognitive symptoms arise.
