A Common Virus Emerging as Potential Culprit in Alzheimer’s Disease
New research adds to evidence that a common herpes virus increases the risk of the neurogenerative condition.
The silent terror of Alzheimer’s disease is slowly robbing millions of their memories and cognitive abilities.
Herpes Simplex Virus May Double Risk of Alzheimer’s
In a Swedish study published in February in the Journal of Alzheimer’s Disease, researchers examined a group of over 1,000 cognitively healthy 70-year-olds over 15 years. The participants were assessed at baseline, then again at ages 75 and 80, and their medical records were followed until age 85.
The researchers analyzed blood samples to detect signs of previous infection with herpes simplex virus (HSV) types 1 and 2, as well as the presence of the apolipoprotein E4 (APOE 4) genetic mutation, which is associated with an increased risk of Alzheimer’s disease.
The study found that individuals who had been infected with HSV-1 at some point in their lives had twice the risk of developing dementia compared to those who had never been infected.
This makes “the results even more reliable since age differences, which are otherwise linked to the development of dementia, cannot confuse the results,” Erika Vestin, a medical student at Uppsala University and study co-author, said in a press statement. “More and more evidence is emerging from studies that, like our findings, point to the herpes simplex virus as a risk factor for dementia.”
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Herpes infections are widespread in the United States, with 50 percent to 80 percent of American adults infected with oral herpes caused by HSV-1, which can cause cold sores or fever blisters to appear in or around the mouth.
Still No Definitive Evidence: Expert
While the line of inquiry into viruses and other disease-related microorganisms in the brain and gut is not new, these topics are currently “hot topics” in neuroscience, Stefania Forner, Alzheimer’s Association director of medical and scientific relations, told The Epoch Times.
One of the primary questions being investigated is whether these microorganisms play an active, causative role in the disease or if they “opportunistically enter the brain,” taking advantage of the damage caused by Alzheimer’s, she noted.
However, there is currently no definitive evidence of a causal relationship between these microorganisms and Alzheimer’s disease, Ms. Forner said. Alzheimer’s is a complex disease with many contributing factors, and multiple causes likely contribute to its underlying biology, she added.
The new study does not prove that herpes viruses caused the onset or contributed to the progression of Alzheimer’s disease, nor does it suggest that antiviral treatment can treat or prevent the condition, according to Ms. Forner.
“The numbers involved are small, and more research needs to be done in historically underrepresented populations,” she added. “Overall, more research is needed to better understand how viral infections and brain health are linked.”
Understanding Viral Links Critical for Future Treatments
“Increasingly, we know the immune system plays an important role in the underlying biology of Alzheimer’s,” Ms. Forner said. “As a result, there are an increasing number of clinical trials targeting immune-related mechanisms.”
However, understanding the potential connections between viruses, microbes, and Alzheimer’s risk could open up new avenues for treatment development.
COVID-19 Adds Urgency to Understanding Viral Effects on Brain
Herpes simplex virus isn’t the only pathogen linked to an increased risk of cognitive decline.
The COVID-19 pandemic has “multiplied the urgency” to understand how viruses may affect the brain, Ms. Forner said.
