A new study has provided further evidence of the gut-brain connection. According to experts, chronic intestinal infections could be linked to the development of Alzheimer’s disease.
An intestinal virus can affect the brain PHOTO: Shuterstock
The research, published in “Alzheimer’s and Dementia,” found that a common virus can take up residence in the human gut and then reach the brain, according to Health.
The virus in question is called human cytomegalovirus (HCMV). The virus is more common in poor countries, where it infects about 90% of the population.
HCMV is a type of herpes virus and remains dormant in the body even after a person recovers from the initial infection. In healthy people, these infections usually cause mild symptoms, such as fever and sore throat, or no symptoms at all.
“Once you’re infected, you’re infected for life. Your immune system can control the virus, but it can never eliminate it from the body.” said Kevin Zwezdaryk, assistant professor of microbiology and immunology at Tulane University School of Medicine.
Because the body can’t completely get rid of HCMV, it’s possible for the virus to be reactivated, reinfecting the gut and potentially reaching the brain, Zwezdaryk explained.
This new study adds to a growing body of research suggesting that herpes viruses, including HCMV, may be a risk factor for developing Alzheimer’s disease in some people, possibly decades before their symptoms appear.
“We don’t have direct evidence for this yet, but we know that Alzheimer’s disease has a preclinical course of several decades,” said study author Benjamin Readhead, a professor at Arizona State University’s ASU-Banner Neurodegenerative Disease Research Center.
How a virus in the gut can affect the brain
In this new study, researchers analyzed brain tissue samples from 101 people who had died, 66 of whom had been diagnosed with Alzheimer’s disease.
Readhead and his colleagues examined brain tissue for a specific type of protein on the surface of microglial cells—these are cells in the brain that regulate development, help maintain neural networks, and repair tissue damage.
After analyzing the tissue samples, the researchers noticed that in Alzheimer’s patients, the presence of the CD83(+) protein was linked to HCMV in both the gut and the brain.
The results of their experiment showed that the virus can accelerate the production by cells of two proteins, amyloid and tau, associated with Alzheimer’s disease.
HCMV is not the only pathogen that has been linked to Alzheimer’s disease. In fact, there are a number of infections caused by viruses, bacteria, and fungi that have been linked to neurodegenerative problems.
But understanding how a single infection can play a role in a person’s brain health is an extremely difficult thing for researchers to study.
“It’s hard to do in a human being because we don’t know when they were infected. We only find it in the post-mortem analysis”, says Brian Balin, director of the Center for Chronic Disorders of Aging at the Philadelphia College of Osteopathic Medicine.
