Cold sores … A bane to peoples’ social lives and now another reason to be dreaded. The virus that causes cold sores (also known as fever blisters) is also being linked with Alzheimer’s disease, the most common form of dementia.
The herpes simplex type 1 virus (HSV-1), which causes cold sores, may make the body more vulnerable to Alzheimer’s if a specific variant of a particular gene is also present. The gene variant is known as ApoE-4 and has been linked to Alzheimer’s for many years. Some scientists, in fact, believe that ApoE-4 is not only a contributing factor to dementia but may actually be a causative factor.
It has been the leading known risk factor for Alzheimer’s for years. However, the concept that it works in conjunction with the herpes virus has taken hold in just the past few years.
Researchers at the University of Rochester Medical Center in New York reported in the journal Neurobiology of Aging that they found ApoE-4 “puts out a welcome mat” for the herpes virus, allowing it to be stronger and more active in the brain.
HSV-1 is a chronic infection that resides within the body for a lifetime, occasionally flaring up when the body is stressed, fatigued, exposed to certain foods or sunlight.
After the original infection, the virus remains dormant in the peripheral nervous system. When the virus is activated, it damages cells and causes cold sores.
Experts report up to 85% of the population has been infected (the older you are, the more likely you have been exposed to it) although only about 15% show symptoms.
Research scientists have suggested for years that viruses could cause inflammation in the brain and inflammation in the brain has been associated with dementia.
The researchers in the University of Rochester study found that the herpes virus remains dormant along with other versions of ApoE; but people who had the ApoE-4 gene variant were the ones that were most likely to suffer active infections along with the hallmark cold sores.
As we age, the herpes virus (HSV-1) spreads to our brains where it can cause the buildup of protein deposits known as beta amyloid plaques and neurofibrillary tangles. These deposits damage the cells responsible for memory, language, and physical functions leading some people to develop Alzheimer’s disease.
Another study investigated the presence of the herpes virus in people’s brains and found that it resided in 90% of the amyloid plaques. Furthermore, research has shown a significant correlation between the amount of beta amyloid in the brain and the degree of cognitive impairment in Alzheimer’s patients.
Over the past several decades our understanding of beta amyloid’s role as a causative factor for dementia has become clearer.
Ruth Itzhaki of the University of Manchester conducted several studies demonstrating a correlation between herpes and Alzheimer’s. She found that people with Alzheimer’s who also had the ApoE-4 gene also had more herpes DNA in the brain regions that are affected by dementia.
Moreover, people with the ApoE-4 gene who had herpes (HSV-1) were more likely to get Alzheimer’s disease than those who lacked both the gene variant and the virus.
Other studies have demonstrated that people who frequently break out in cold sores are more likely to have the ApoE-4 gene variant that makes them more vulnerable to Alzheimer’s.
According to Howard Federoff, M.D., Ph.D. at Georgetown University, “The link between herpes and Alzheimer’s has been there for a while, but more people are starting to pay attention, it’s no longer just a curiosity.”
Researchers and experts conclude that it is no longer a question of whether HSV-1 is involved in dementia, but rather how significant the involvement is.
They suggested that the next step is to investigate whether anti-viral drugs used for treating acute herpes can be utilized for preventing or slowing down cognitive decline in patients with Alzheimer’s.
Researchers also recommended that people treat a cold sore as quickly as possible in order to minimize the time the herpes virus is active in their nervous system. The quicker you treat a cold sore, the faster the herpes virus returns to its dormant stage.