New ways of studying Alzheimer’s disease could lead to a new drug to prevent it
Polio was a dreadful, disabling condition treated by placing victims, adults and children alike, in “iron lungs,” old-fashion negative-pressure respirators for paralyzed patients. U.S. hospitals at the time marketed themselves by showcasing their iron lung units.
The lives of children and adults were substantially affected: no swimming in public pools, rivers, oceans; no meetings with “strangers,” isolation and constant fear of paralysis or death. That was until Jonas Salk discovered and distributed the poliovirus — or PV — vaccine in 1955.
PV was attacking our motor neurons, the nerve cells that transmit our commands to muscle cells, leading to paralysis. There are other viruses that have a predilection for the human nervous system, such as the human herpes viruses. In fact, there are nine of them.
Diseases caused by this virus family include cold sores, genital ulcers chicken pox and shingles, mononucleosis and the one that causes the most common cancer seen in AIDS patients, Kaposi’s sarcoma herpes virus.
However, they all seem to share an attraction for our brains. We are not sure what they are doing there, though.
Alzheimer’s disease, AD, is today’s polio-equivalent challenge. It affects 1.6 people out of 100 in the United States, about 5 million. However, taking into account population growth, 3.3 people out of 100, or 13.9 million, will be affected by 2060, according to the Centers for Disease Control and Prevention. Clearly, this is our major health issue for the 21st century.
Alzheimer’s disease is the most frequent and debilitating type of dementia for patients, for their families and care givers. The strongest risk for AD is aging.
But we all age, right? Isn’t it a natural thing? Why would a scourge like AD be a part of a natural process like becoming old? For a long time, scientists have thought that the culprit protein for AD is “amyloid-beta,” which accumulates in regions of older people’s brain and forms the typical “plaque” seen in large numbers in the brain tissue of AD patients. Hundreds of billions of dollars have been invested in drugs and other therapeutic agents to fight A-beta in AD brains, and so far, with negligible or no benefit to patients.
New studies published in 2018 have refocused our attention on a possible “viral” cause for Alzheimer’s disease. One team, supported by the National Institutes of Health has presented powerful evidence that tracks of herpes viruses 6A and 7, which cause a benign illness during childhood and are detected in greater amounts than other viruses selectively in the brains of AD patients (even relative to other chronic brain disorders). Two studies done in Taiwan have shown that new infections with two other herpes viruses seem to cause AD. They also show that treating patients with available drugs against these viruses reduced markedly the excess dementia caused by them, a 90 percent reduction or more. Other researchers have published on the relationship between herpes viruses and host genetic factors that are known to promote AD.
We do not know whether herpes viruses, with or without host genetic susceptibility, can cause AD or not. But scientists have been investigating this possibility for as long as the polio vaccine has existed. And as with the polio vaccine, the best way to find out if a virus can cause an illness, is to perform a clinical trial where half the patients receive a safe and effective agent against the implicated herpes virus(es), and half receive a placebo (sugar pill), then see if the drug-treated patients have a better outcome than the placebo-treated patients in terms of thinking ability and ability to function in daily life.
Researchers believe that based on these recent studies of human herpes viruses and AD, we may be approaching a major paradigm shift in our approach to the disease, instead of continuing on our current path of spending billions on failing AD studies.
Fred G. Volinsky, M.D., is the founder and Pascal J. Goldschmidt-Clermont, M.D., is cofounder of Epiphany Biosciences Inc. Steven P. LaRosa, M.D., is an infectious disease physician at Lahey Health, Beverly.
This story was originally published October 30, 2018 at 5:28 PM.