A new study suggests a potential link between a common viral gut infection and the progression of Alzheimer's disease. Researchers believe a specific subtype of the disease, impacting 25-45% of cases, may be triggered by the cytomegalovirus (CMV). This finding could lead to new treatment avenues.
The study, published in Alzheimer's & Dementia, found that CMV, a herpes virus, may travel from the gut to the brain via the vagus nerve. Once there, it appears to trigger immune system changes associated with Alzheimer's. Specifically, the virus prompts immune cells called microglia to express a gene, CD83, previously linked to Alzheimer's. This sustained immune response can lead to chronic inflammation and neuronal damage, contributing to disease progression.
Crucially, this study builds on previous research. A 2024 Nature study found a higher prevalence of CD83 microglia and relevant antibodies in Alzheimer's patients' post-mortem brains, suggesting a potential infectious component. The latest research corroborates this, identifying CMV antibodies and the presence of the virus in the vagus nerve of Alzheimer's patients.
This new understanding provides a potential pathway for future treatment. If validated, existing antiviral drugs could be repurposed to target and potentially mitigate this form of Alzheimer's. Researchers are also developing a blood test to identify patients with active CMV infections, enabling early intervention and prevention.
"We believe we've identified a unique biological subtype of Alzheimer's," commented co-author Ben Readhead. "This involves hallmarks like amyloid plaques and tau tangles, coupled with a distinct profile of virus, antibodies, and immune cells within the brain."
Further investigation is needed to confirm the findings and explore the specific mechanisms involved. However, the study offers a promising avenue for understanding Alzheimer's and developing innovative treatments.
