Sean Cate

Sean Cate

January 16, 2025

Virus Most People Encounter May Play a Role in Developing Alzheimer’s, Study Suggests

A recent study is showing a potential link between a common infection and the development of Alzheimer’s disease. Researchers believe that this virus may be a contributor to the onset of Alzheimer’s in a significant number of patients.

Understanding The Virus

Blood sample with requisition form for cytomegalovirus (CMV) test
Source: Shutterstock

Cytomegalovirus (CMV) is one of nine herpesviruses that many individuals are exposed to during their early years. Unlike some other herpesviruses, CMV is not considered sexually transmitted. After the initial infection, the virus often remains dormant in the body for life. By age 80, approximately 90% of people will have antibodies indicating exposure to CMV.

The Gut-Brain Connection

a stomach with a few things in it
Credit: Pixabay

Researchers at Arizona State University and Banner Alzheimer’s Institute suggest that in some individuals, CMV can establish a chronic infection in the gut. From there, the virus may travel to the brain via the vagus nerve, a crucial pathway connecting the gastrointestinal system to the brain. This migration could potentially trigger changes in the immune system associated with Alzheimer’s disease.

Microglia Activation and Gene CD83

Brain’s immune cells, light blue and purple, shown interacting with amyloid plaques, red, linked to Alzheimer’s disease
Credit: Arizona State University

Once in the brain, CMV may prompt immune cells called microglia to express higher levels of the gene CD83. Microglia are responsible for cleaning up debris and plaques in the brain, but their overactivation can lead to chronic inflammation. The expression of CD83 has been linked to Alzheimer’s progression, contributing to neuronal damage.

Implications for Treatment and Prevention

a person's memory being erased
Credit: Pixabay

The discovery opens the possibility of using existing antiviral medications to treat or prevent this form of Alzheimer’s disease. “We think we found a biologically unique subtype of Alzheimer’s that may affect 25-45% of people with this disease,said Dr. Ben Readhead, co-author of the study. Developing blood tests to detect active CMV infections could identify patients at risk and allow for early intervention.

Supporting Evidence from Previous Studies

immune system cells with microglia around them
Credit: Science Photo Library

An earlier study published in Nature found that the brains of Alzheimer’s patients were more likely to contain microglia expressing CD83. Additionally, antibodies indicating an infection were present in their intestines, suggesting a link between gut infections and Alzheimer’s. These findings reinforce the potential role of CMV in the disease’s development.

Challenges and Future Research

CMV-infected human placental cell.
Credit: Wikimedia Commons

While the association between CMV and Alzheimer’s is compelling, further research is necessary to validate these findings. Understanding why only a subset of individuals with CMV develop Alzheimer’s remains a critical question. Future studies aim to explore the mechanisms behind CMV’s impact on the brain and to develop reliable diagnostic tests.

A New Perspective on Alzheimer’s Disease

an elderly man walking down tthe street missing part of his mind

This research highlights the importance of considering infections and immune responses in Alzheimer’s disease. By identifying a potential viral trigger, scientists hope to open new avenues for treatment and prevention. “This subtype of Alzheimer’s includes the hallmark amyloid plaques and tau tangles,” noted Dr. Readhead, emphasizing the significance of their findings.

The possible link between a common virus and Alzheimer’s disease offers a promising direction for future research. If validated, targeting CMV could become a pivotal strategy in combating Alzheimer’s, potentially improving the lives of millions affected by this devastating condition.

Read More: More and More Evidence Is Showing That Alzheimer’s Disease is Linked to Gut Health