Does Herpes Cause Alzheimer’s?

Two Swedish studies published in Alzheimer’s & Dementia have found evidence that the herpes simplex virus — the virus that causes common cold sores — doubles the risk of developing Alzheimer’s disease. 

 

In one study, researchers followed nearly 3,500 people over an average period of 11 years and found that the presence of certain antibodies to herpes seems to double the likelihood of the infected person developing the neurological disorder. In the second study, blood samples from 360 Alzheimer’s patients indicated a link between herpes and Alzheimer’s.

 

“Herpes virus causes a significant proportion of all cases of AD — about 40 to 50 percent — according to our data,” lead researcher Hugo Lovheim, an associate professor in the department of community medicine and rehabilitation at Umea University in Sweden, told website Psych Central.

 

Other specialists, including Greg Cole, the associate director of the Geriatric Research and Clinical Center at the University of California, Los Angeles, Alzheimer Disease Research Center, aren’t convinced about the link, as the herpes simplex virus is so common. “More than 90 percent of the population has antibodies to herpes,” Cole told the site. “They are not all destined to develop Alzheimer’s disease.” 

 

The oral herpes virus infects epithelial cells found in the mouth. Once a person is infected, the virus replicates and uses nerve pathways to travel to the brain, where it establishes a latent infection. Cold sores occur when the virus periodically travels back to the original site of infection. Reactivated and traveling in the nervous system, the virus may cause acute neurological disorders such as encephalitis and low-grade, asymptomatic infections, or it might establish lifelong latent infections, which could launch the progression of Alzheimer’s toward dementia. 

 

“The identification of a treatable cause of the most common dementia disorder is a breakthrough,” Lovheim said. “Whether treatment of herpes infection with antiviral drugs may slow the Alzheimer’s progression is not known, but is certainly worth investigating in clinical studies.”