In an editorial in the Journal of Alzheimer’s Disease, 33 clinicians and scientists proposed that Alzheimer’s disease is caused when specific bacterial infections or the herpes simplex virus-1 (i.e., the virus that causes cold sores) trigger inflammation in the brain. If the theory is true, we could potentially treat Alzheimer’s with antibacterial or antiviral drugs.
The idea is not new—HSV-1 infections were linked with Alzheimer’s as far back as 1982. Many scientists remain skeptical, however. Many elderly people have the HSV-1 virus without the signs of Alzheimer’s disease. Bacteria and fungi have also been found in the brains of Alzheimer’s disease patients, without the presence of HSV-1. It would be surprising if bacteria, viruses, and fungi were to cause the same unique damage that underlies Alzheimer’s disease. Most likely, the stress of Alzheimer’s disease makes the brain vulnerable to many types of infection. Though, the infections might impose stress and inflammation that further weakens the brain and accelerates the progression of Alzheimer’s disease.
So what can we do? First, we need conclusive research to prove or disprove these theories. And then, we need to develop treatments to block the infections. Anti-viral drugs like valacyclovir are already on the market, and studies show they can block viruses such as HSV-1 from major reactivations. But we don’t yet know if or how the drugs might be used to block the mild reactivations that are not apparent from the outside yet (theoretically) might be leading to a long-term risk of Alzheimer’s disease.
At the Alzheimer’s Drug Discovery Foundation, we aim to leave no stone unturned in the hunt for a cure. In 2015, we wrote a scientific report on the potential of anti-viral drugs to prevent or treat Alzheimer’s disease. Our conclusion was that the idea has merit but needs substantially more research to be useful for the development of treatments. The full 2015 report, written for scientific staff, is available as a download.
Dr. Penny Dacks was previously the Director of Aging and Alzheimer’s Disease Prevention at the Alzheimer's Drug Discovery Foundation. She was trained in neuroscience at the Mount Sinai School of Medicine, the University of Arizona, and Queen's University (Canada) with individual fellowships from the National Institute of Health, the Evelyn F. McKnight Brain Research Foundation, the ARCS Foundation and the Hilda and Preston Davis Foundation. She has authored over 18 peer-reviewed scientific articles and is a member of the Society for Neuroscience, the Gerontological Society of America, the Endocrine Society and the Association for Women in Science.
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