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Brain Changes from COVID Affect Memory!

Are you experiencing more brain fog than usual? Did you catch COVID without even knowing it? Brain shrinkage and cognitive decline can result

Long COVID continues to cause a lot of misery. Previous research hinted at brain shrinkage after infection. That may occur even if people experience only mild symptoms! Now, radiologists report that MRI imaging scans reveal brain changes in the frontal lobe and brain stem (Annual Meeting of the Radiological Society of North America, Nov. 21, 2022). Other research from the UK demonstrates significant memory problems after COVID-19 infection.

Concrete Signs of Brain Changes After COVID:

People who are suffering from long COVID often complain of “brain fog.” That is a way of describing a bunch of diverse symptoms including trouble concentrating, muddled thinking, lost words, confusion, short-term memory loss and mental fatigue. Neurologists lump this all together and call it cognitive dysfunction.

Such symptoms are vague, however. What’s actually going on in the brain to cause these cognitive difficulties? Radiologists can examine small structural abnormalities by using specialized MRI (magnetic resonance imaging) techniques to detect subtle brain changes.

The researchers in this study compared the brains of 30 healthy individuals to those of 46 people who recovered from COVID. The imaging was conducted within six months of recovery. It detected significant differences in specific areas of the brain, particularly the frontal lobe and the brain stem. Circulation through small blood vessels in these areas appears to be compromised and could contribute to cognitive dysfunction.

Inflammation in Tissue Culture:

Other researchers have employed specialized laboratory techniques to grow microglia brain cells in culture. They infected these cells with SARS-CoV-2 (Molecular Psychiatry, Nov. 1, 2022). In response, the microglia became inflamed, just as they would in a brain developing Parkinson or Alzheimer disease.

Such neurodegenerative conditions take years to show themselves, with the inflammation slowly but inexorably killing neurons. The spike protein from the virus was enough to trigger inflammation, but the process was more rapid when the cells were already primed to develop Parkinson disease.

Brain Changes and Memory Problems!

Most of us will not have specialized MRI scans. No one will tell us if our brains have changed. But we will know if we are experiencing brain fog or cognitive dysfunction. Researchers are also trying to see what kinds of memory problems people with long COVID are suffering.

Researchers at Hull York Medical School in the UK administered an online survey and memory quiz called CORONA (PLoS One, Nov. 14, 2022). CORONA stands for COVID-19 Online Rapid Objective Neuro-Memory Assessment. There were roughly 5400 volunteers who participated in the CORONA study.

The authors note that about 20% of patients who contract the coronavirus experience “memory impairments in the post-illness phase.”

They were particularly interested in something called “working memory”:

“Working memory, a form of short-term memory, is the dynamic process by which information is stored and retrieved while performing a task. Working memory is critically important in daily living; it is involved in tasks such as problem solving, reasoning, reading comprehension, having a conversation, and is highly correlated with measures of cognitive function.”

Objective memory scores were significantly lower among people who had caught COVID-19.

Here is how they describe their results:

“The main finding was that objective memory scores were significantly reduced in the self-reported, positive-tested and hospitalized COVID groups compared to the non-COVID group. These results suggest that COVID-19 affects working memory function. With respect to age, we found that memory scores for the COVID group were reduced compared to the non-COVID group in every age category 25 years and over, but not for the youngest age category (18–24 years old).”

Brain Shrinkage and Long COVID:

Scientists continue to learn about the long-term consequences of COVID-19 infections. Unfortunately, even mild infections can result in brain changes.

This research relied upon data collected from the UK Biobank (Nature, March 7, 2022). There were 785 participants who underwent MRI brain imaging and cognitive testing before COVID.

Three years later, about half of the volunteers had recovered from mild coronavirus infections. Repeat MRI brain scans revealed modest brain shrinkage in certain anatomical regions.

Where Is Brain Shrinkage Detectable?

The orbitofrontal cortex is responsible for the senses of smell and taste. The parahippocampal gyrus plays an important role in memory. Both areas were smaller after COVID infection. Tests of brain function showed some cognitive decline among people who had recovered from infection.

The authors conclude:

“To our knowledge, this is the first longitudinal imaging study of SARS-CoV-2 where participants were initially scanned before any had been infected. Our longitudinal analyses revealed a significant, deleterious impact associated with SARS-CoV-2.

“Finally, significantly greater cognitive decline, which persisted even after excluding the hospitalised patients, was seen in the SARS-CoV-2 positive group between the two timepoints, and this decline was associated with greater atrophy of crus II, a cognitive lobule of the cerebellum.”

How Many People May Have Brain Shrinkage Because of COVID?

As I write this, the official case count is that more than 97,000,000 people in the US have caught COVID-19. That may be an undercount.

It is estimated that the number of people who have been infected with COVID is probably over 186 million.  That number is based on antibodies detected in blood samples at commercial labs. Many probably did not even know that they had caught COVID-19. If “only” 10% have some residual brain issues, that represents so many millions of people that my head spins.

Brain Symptoms After COVID Infections:

SARS-CoV-2, the virus causing COVID-19, seems to target the nervous system as well as the lungs.

Researchers writing in Science (Jan. 20, 2022) note that there are:

“…myriad neurological complications—including confusion, stroke, and neuromuscular disorders—manifest during acute COVID-19. Furthermore, maladies such as impaired concentration, headache, sensory disturbances, depression, and even psychosis may persist for months after infection, as part of symptoms now called Long COVID.”

There are probably many factors that lead to brain fog and memory problems. As you have read, they include inflammation of blood vessels as well as of nervous system tissue. Brain shrinkage could be contributing to symptoms such as headaches, brain fog and cognitive dysfunction.

We won’t know for many years whether infection with SARS-CoV-2 will increase the incidence of neurological conditions like memory problems, Alzheimer’s or Parkinson’s disease. Only time will tell if people recover or descend into permanent brain fog.

Share Your Thoughts:

Have you caught COVID-19? Have you experienced any neurological symptoms or cognitive dysfunction? Please share your experience in the comment section below.

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About the Author
Joe Graedon is a pharmacologist who has dedicated his career to making drug information understandable to consumers. His best-selling book, The People’s Pharmacy, was published in 1976 and led to a syndicated newspaper column, syndicated public radio show and web site. In 2006, Long Island University awarded him an honorary doctorate as “one of the country's leading drug experts for the consumer.”.
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  • Albornoz EA et al, "SARS-CoV-2 drives NLRP3 inflammasome activation in human microglia through spike protein." Molecular Psychiatry, Nov. 1, 2022. DOI: https://doi.org/10.1038/s41380-022-01831-0
  • Douaud, G., et al, "SARS-CoV-2 is associated with changes in brain structure in UK Biobank," Nature, March 7, 2022, https://doi.org/10.1038/s41586-022-04569-5
  • Baseler, H.A., et al, "The negative impact of COVID-19 on working memory revealed using a rapid online quiz," PLOS One, Nov. 14, 2022, doi: 10.1371/journal.pone.0269353
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