A groundbreaking collaboration between Arizona State University and Banner Alzheimer’s Institute researchers has uncovered an unexpected connection between a common viral infection in the gut and Alzheimer’s disease, potentially affecting up to 45% of patients with the condition. The discovery opens new possibilities for treatment using existing antiviral medications.
Published in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association | Estimated reading time: 5 minutes
Most humans encounter cytomegalovirus (HCMV) early in life, but new research suggests this seemingly innocuous infection might have far-reaching consequences for brain health. In a significant discovery, researchers have found that in some individuals, this virus can establish a persistent presence in the gut before making its way to the brain through an unexpected route: the vagus nerve.
“We think we found a biologically unique subtype of Alzheimer’s that may affect 25% to 45% of people with this disease,” says Dr. Ben Readhead, research associate professor with ASU-Banner Neurodegenerative Disease Research Center and co-first author of the study. “This subtype of Alzheimer’s includes the hallmark amyloid plaques and tau tangles—microscopic brain abnormalities used for diagnosis—and features a distinct biological profile of virus, antibodies and immune cells in the brain.”
The investigation revealed that when HCMV reaches the brain, it triggers a response from microglia – the brain’s immune cells. While these cells initially serve a protective function, their sustained activation can lead to chronic inflammation and neuronal damage. The research team demonstrated that virus exposure increased the production of amyloid and phosphorylated tau proteins, contributing to neuronal degeneration.
The significance of this finding extends beyond just identifying a potential cause. The researchers are currently developing a blood test to identify individuals with chronic intestinal HCMV infection, opening the possibility of using existing antiviral medications as a treatment approach for this subset of Alzheimer’s patients.
Dr. Eric Reiman, Executive Director of Banner Alzheimer’s Institute and the study’s senior author, emphasizes the collaborative nature of this breakthrough: “We are extremely grateful to our research participants, colleagues, and supporters for the chance to advance this research in a way that none of us could have done on our own.”
Glossary
- Cytomegalovirus (HCMV): A common herpes virus typically transmitted through bodily fluids that can establish long-term presence in the body.
- Microglia: The brain’s immune cells that respond to infections and can contribute to inflammation when chronically activated.
- Vagus nerve: A critical nerve pathway connecting the gut and brain, serving as an information highway between these organs.
Test Your Knowledge
What percentage of people show evidence of HCMV antibodies by age 80?
About 80% of people show evidence of antibodies by age 80.
Through what pathway does the virus potentially travel from the gut to the brain?
The virus may travel through the vagus nerve, which connects the gut and brain.
What specific gene is activated in brain immune cells when they recognize the virus?
The microglia turn on the expression of the CD83 gene.
What cellular changes did researchers observe when exposing human brain cell models to the virus?
The virus increased production of amyloid and phosphorylated tau proteins and contributed to neuronal degeneration and death.
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