A groundbreaking study suggests that Alzheimer’s disease, one of the most challenging medical mysteries of our time, could sometimes be linked to a herpes virus.
Researchers in the United States have identified evidence of cytomegalovirus (HCMV) infections in the brains of individuals who died with Alzheimer’s. This discovery has sparked new theories about the virus’s potential role in up to 45% of cases.
HCMV, a member of the herpes family, typically exists harmlessly in a dormant state in the gut. However, scientists now believe that the virus remains active in some individuals and travels to the brain via the vagus nerve—a vital pathway connecting the gut and brain. Once in the brain, HCMV may trigger immune responses that lead to the development of amyloid plaques and tau tangles, hallmarks of Alzheimer’s that interfere with neural communication, reported The Telegraph.
“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,” explained Dr. Ben Readhead of Arizona State University. His team’s findings suggest a unique biological pathway for this disease, implicating the virus as a critical factor.
Post-mortem analysis revealed that Alzheimer’s patients had significantly more immune cells linked to inflammation compared to individuals without the disease. The virus was detected in the intestines, spinal fluid, and the vagus nerve, providing compelling evidence of its journey to the brain. These findings offer a promising new perspective on the disease’s development and progression.
HCMV is usually spread through bodily fluids and remains inactive in most individuals.
About 80% of people show antibodies indicating exposure by the age of 80, but the virus only becomes active in certain cases. Among Alzheimer’s patients studied, active HCMV was a prominent feature, strengthening the hypothesis of its role in the disease.
The researchers are now focused on developing a blood test to detect chronic intestinal HCMV infections. If successful, this could lead to targeted antiviral treatments aimed at preventing Alzheimer’s in at-risk individuals.
“We’re excited about the chance to have researchers test our findings in ways that make a difference in the study, subtyping, treatment and prevention of Alzheimer’s disease,” said Dr. Eric Reiman, senior author and executive director of the Banner Alzheimer’s Institute in Arizona.