By George Citroner
Besides aging, viral infections are also factors that contribute to Alzheimer’s disease. 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 and COVID 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 press 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 Alzheimer’s onset and pathology. With COVID-19’s global reach and extensive neurological impact, experts fear 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.
A retrospective study of over 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 over 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 press statement.
A sustained rise in Alzheimer’s diagnoses after COVID-19 could substantially strain long-term care resources, she added.
“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,” she added. “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 (ALS) 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 Alzheimer’s risk. 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 Alzheimer’s-like amyloid buildup.
While studies have shown an association between viral infections and neurological disease, including Alzheimer’s disease, “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 viruses like influenza A, murine cytomegalovirus (a common herpes virus), and COVID-19 can also 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 added.
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 viruses’ impact on neurodegeneration, ubiquitous COVID-19, is essential, Dr. Palekar said, noting that millions of people have been infected and “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 added.