Alzheimer’s Linked to COVID-19 and Other Common Viral Infections

Many factors increase brain disease risk, but infection with common viruses could be the most insidious.
Alzheimer’s Linked to COVID-19 and Other Common Viral Infections
George Citroner

COVID-19 looks to join the list of viruses now linked to neurological disorders. COVID-19 has increasingly been linked to cognitive decline, a connection that appears to be confirmed by a new review of neurological symptoms connected to the condition.

According to researchers, the viral infection significantly adds to the risk of dementia in older people. In effect, Alzheimer’s disease and COVID-19 appear to work together to damage our brains.

“I believe over the next several years, emerging evidence will further support a link between microbial infection and neurodegenerative diseases,” corresponding author of the study Thomas E. Lane, who holds a doctorate in microbiology and immunology, said in a statement.

Alzheimer’s Diagnoses May Surge Post-COVID

COVID-19 and Alzheimer’s share inflammatory features and risk factors, according to the review. Inflammation may contribute to the onset and pathology of Alzheimer’s. With COVID-19’s global reach and extensive neurological effects, experts are concerned that it may act as a risk factor for Alzheimer’s or worsen existing pathology. If COVID-19 increases Alzheimer’s risk, the combined effects of these devastating diseases could have major public health consequences worldwide.

Past research links viral infections to degenerative brain disease.

A retrospective study of more than 6.2 million people aged 65 years and older found a 69 percent increased Alzheimer’s diagnosis risk within a year of COVID-19 infection, especially in women and those older than 85.

“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, said in a statement.

A sustained rise in Alzheimer’s diagnoses after COVID-19 could substantially strain long-term care resources, she said.

“We thought we had turned some of the tide on [Alzheimer’s] by reducing general risk factors such as hypertension, heart disease, obesity, and a sedentary lifestyle,” Dr. Davis said. “Now, so many people in the U.S. have had COVID, and the long-term consequences of COVID are still emerging. It is important to continue to monitor the impact of this disease on future disability.”

Other Viruses Linked to Higher Risk of Alzheimer’s

Hospitalizations resulting from pneumonia-causing flu viruses were linked to diagnoses of several neurological disorders, including dementia, Parkinson’s disease, and amyotrophic lateral sclerosis, up to 15 years after diagnosis, a National Institutes of Health study published in April found.

The largest association was between viral encephalitis and Alzheimer’s.

Another recent study discovered that the common cold sore virus (herpes simplex virus) can increase the risk of Alzheimer’s. After infection, it often resides dormant in nerves, where stress can reactivate it.
DNA from the herpes simplex-1 virus has been found in a significant number of older individuals’ brains.

Researchers also discovered that shingles can reactivate the virus and cause an Alzheimer’s-like amyloid buildup.

While studies have shown an association between viral infections and neurological disease, including Alzheimer’s, “the exact mechanism by which this occurs is not entirely clear,” Dr. Nikhil Palekar, director of the Stony Brook Center of Excellence for Alzheimer’s Disease and director of the Stony Brook Alzheimer’s Disease Clinical Trials Program, told The Epoch Times.

Viral Infection Worsens Key Sign of Alzheimer’s

Studies show that viruses such as influenza A, murine cytomegalovirus (a common herpes virus), and COVID-19 can cause amyloid proteins to accumulate in the brain, according to Dr. Palekar.

“Amyloid accumulation and amyloid plaque formation is one of the core pathological features seen in Alzheimer’s disease,” he said.

A recent study on the SARS-CoV-2 virus, which causes COVID-19, revealed disruptions in amyloid-beta and tau proteins, increasing their toxic neuronal effects to potentially cause Alzheimer’s.

Studying the effect of viruses on neurodegeneration is essential, Dr. Palekar said, noting that millions of people have been infected and that “a large majority of them” experience long- or short-term neurological symptoms.

“Understanding the specific mechanisms by which viruses affect brain functions is critical and will drive the development of targeted therapeutics in reducing or even preventing virus-mediated neurodegeneration,” he said.

George Citroner reports on health and medicine, covering topics that include cancer, infectious diseases, and neurodegenerative conditions. He was awarded the Media Orthopaedic Reporting Excellence (MORE) award in 2020 for a story on osteoporosis risk in men.
Related Topics