Herpes Viruses and Alzheimer’s Disease

After reading an article published by the New Scientist {https://www.newscientist.com/article/2172294-herpes-viruses-in-the-brain-linked-to-alzheimers-disease/} entitled: “Herpes viruses in the brain linked to Alzheimer’s disease” I decided to write a post to explore the ideas presented in this study.

The article explores the notion of a relationship between the HHV-6 virus and Alzheimer’s disease. The signficance of this is huge- if there is a relationship that can be determined between the presence of the virus in Alzheimer’s patients, the disease could possibly be treated with Anti-Viral drugs. Keeping in mind that Alzheimer’s disease is the single largest cause of dementias which affects around 50 million people world wide.

An article on the same topic written by Ed Cara {https://gizmodo.com/herpesviruses-linked-to-alzheimers-disease-in-new-brain-1827020949} explored the role of viruses in relation to the emergence of Alzheimer’s disease. Viruses have long been thought to play a role in the pathway of events in the neurodegeneration involved in Alzheimer’s. The study originally had no interest in testing the theory of the viral role in Alzheimer’s disease however after studying brain samples of deceased Alzheimer’s patients and then comparing with specimens who had died free of disease, the team found several species of herpes viruses that were more common in the brains of people with Alzheimer’s. Greater amounts of herpes virus found in the brain were also associated with someone having worse levels of dementia before death, providing futher support for a connection between the herpes virus (specifically HHV-6A and HHV-7) and Alzheimer’s.

The research team modelled how HHV-6A and HHV-7 could interact with the brain. The findings concluded that HHV-6A and HHV-7 genes were regularly turning on and off human genes in these brains and vice-versa. HHV-6A and HHV-7 are genes that have previously been implicated in raising a patient’s risk of Alzheimer’s. These interactions were further observed in areas, such as the hippocampus, that are especially affected by Alzheimer’s. The fact that the herpes genes could turn on and off genes in the brain indicates that there could be environmental factors that trigger someone’s genetic susceptibility to the disease.

Crucially, herpes viruses are found in 90 percent of American’s but the entirety of the that cohort will not develop Azlheimer’s. It is currently theorised that these viruses lie dormant in the body and migrate to the brain or nervous system at some point. However, it is believed that environemental factors could trigger the viruses to activate the genes thereby allowing the brain to interact with these genes, ultimately accelerating the progression of Alzheimer’s.

Furthermore, research has suggested that HSV-1 increases a persons risk of Alzheimer’s only if they are already a carrier of the APOE E-4 gene, an already known risk factor. Other research is also suggestive of the idea that both viruses interact with the human genes that produce beta-amyloid, which compose the plaques that cause the neurodegeneration of an Alzheimer’s brain.

The research currently being conducted into the microbial role in Alzheimer’s offers a new dimension to be explored in preventing and treating the disease, something that could possibly reduce the fatality of one of the biggest killers in our society today.

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