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What is Alzheimer’s disease?
Alzheimer’s disease is the most common cause of dementia (memory loss). It is a chronic ongoing condition that slowly destroys thinking and memory skills and reduces the ability to carry out simple tasks. People who are 65 and older are prone to this condition. Patients report symptoms of loss of memory, confusion with place and time, inability to perform tasks, challenges in problem-solving, etc.
How can a virus lead to Alzheimer’s disease?
Alzheimer’s disease is caused by the abnormal build-up of proteins in and around the brain cells. Herpes simplex-1 (HSV-1), one of the variants of the virus, when gets activated leads to the accumulation of amyloid beta and tau proteins that disturb neuronal function, the new research states.
According to World Health Organization (WHO), 3.7 billion people have been infected with HSV-1, a virus that causes oral herpes (mouth infection). When this virus gets activated, it causes inflammation in the skin and nerves, causing painful blisters and sores. Varicella zoster virus (VZV), a virus that causes shingles and chickenpox, is also common in people. About 95 percent of people have been infected by this virus. VZV is a form of the herpes virus that activates and results in painful nodules and blisters on the skin.
The link between Alzheimer’s disease and HSV-1 occurs when HSV-1 reactivates to cause inflammation, sores and blisters.
Researchers observed that the VZV-infected neurons started to produce higher levels of cytokines, proteins inducing inflammatory responses. Further, the levels of amyloid beta and tau proteins also increased. Also, the neurons began to function less efficiently. They noted that VZV could lead to the activation of HSV and increased inflammation. Repeat cycles of HSV-1 activation can lead to the production of plaques, accumulation of cognitive and neuronal damage and inflammation in the brain.
Researchers said that other factors such as alcohol use, infections and head trauma might be involved in Alzheimer’s disease. They also added that COVID-19 infections might trigger viruses and neurodegeneration. A VZV vaccine which can prevent shingles and chickenpox has been shown to reduce the risk of dementia. The vaccine could be helping to stop neural damage, inflammation and the cycle of viral reactivation.
The detailed study has been published in the Journal of Alzheimer’s disease.
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