Many factors increase brain disease risk, but infection with common viruses could be the most insidious.
A recent review of neurological symptoms connected to COVID-19 has confirmed a link between the virus and cognitive decline, adding to the growing body of evidence that common viral infections, including influenza and herpes simplex, may increase the risk of Alzheimer’s disease. This connection, which appears to be particularly significant in older individuals, suggests that viral infections could have far-reaching implications for public health and the future study of neurodegenerative diseases.
- COVID-19 has been linked to an increased risk of dementia in older people, with a retrospective study of over 6.2 million people aged 65 years and older finding a 69 percent increased Alzheimer’s diagnosis risk within a year of COVID-19 infection.
- Alzheimer’s and COVID-19 share inflammatory features and risk factors, and inflammation may contribute to Alzheimer’s onset and pathology.
- Other viruses, including those causing pneumonia and the common cold sore (herpes simplex virus), have also been linked to an increased risk of Alzheimer’s disease.
- Viral infections can cause amyloid proteins to accumulate in the brain, a core pathological feature seen in Alzheimer’s disease.
- The SARS-CoV-2 virus, which causes COVID-19, has been found to disrupt amyloid-beta and tau proteins, potentially increasing their toxic neuronal effects and leading to Alzheimer’s.
The factors that play into the development of Alzheimer’s disease have been poorly understood, but two pieces considered important are prior infections, especially viral infections, and inflammation.
— Dr. Pamela Davis, distinguished professor at Case Western Reserve University and study co-author
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