By Ziyad Al-Aly
From the very early days of the pandemic, brain fog emerged as a significant health condition that many experience after COVID-19.
Brain fog is a colloquial term that describes a state of mental sluggishness or lack of clarity and haziness that makes it difficult to concentrate, remember things and think clearly.
Fast-forward four years and there is now abundant evidence that being infected with SARS-CoV-2 – the virus that causes COVID-19 – can affect brain health in many ways.
In addition to brain fog, COVID-19 can lead to an array of problems, including headaches, seizure disorders, strokes, sleep problems, and tingling and paralysis of the nerves, as well as several mental health disorders.
A large and growing body of evidence amassed throughout the pandemic details the many ways that COVID-19 leaves an indelible mark on the brain. But the specific pathways by which the virus does so are still being elucidated, and curative treatments are nonexistent.
Now, two new studies published in the New England Journal of Medicine shed further light on the profound toll of COVID-19 on cognitive health.
I am a physician scientist, and I have been devoted to studying long COVID since early patient reports about this condition – even before the term “long COVID” was coined. I have testified before the U.S. Senate as an expert witness on long COVID and have published extensively on this topic.
How COVID-19 leaves its mark on the brain
Here are some of the most important studies to date documenting how COVID-19 affects brain health:
- Large epidemiological analyses showed that people who had COVID-19 were at an increased risk of cognitive deficits, such as memory problems.
- Imaging studies done in people before and after their COVID-19 infections show shrinkage of brain volume and altered brain structure after infection.
- A study of people with mild to moderate COVID-19 showed significant prolonged inflammation of the brain and changes that are commensurate with seven years of brain aging.
- Severe COVID-19 that requires hospitalization or intensive care may result in cognitive deficits and other brain damage that are equivalent to 20 years of aging.
- Laboratory experiments in human and mouse brain organoids designed to emulate changes in the human brain showed that SARS-CoV-2 infection triggers the fusion of brain cells. This effectively short-circuits brain electrical activity and compromises function.
- Autopsy studies of people who had severe COVID-19 but died months later from other causes showed that the virus was still present in brain tissue. This provides evidence that contrary to its name, SARS-CoV-2 is not only a respiratory virus, but it can also enter the brain in some individuals. But whether the persistence of the virus in brain tissue is driving some of the brain problems seen in people who have had COVID-19 is not yet clear.
- Studies show that even when the virus is mild and exclusively confined to the lungs, it can still provoke inflammation in the brain and impair brain cells’ ability to regenerate.
- COVID-19 can also disrupt the blood brain barrier, the shield that protects the nervous system – which is the control and command center of our bodies – making it “leaky.” Studies using imaging to assess the brains of people hospitalized with COVID-19 showed disrupted or leaky blood brain barriers in those who experienced brain fog.
- A large preliminary analysis pooling together data from 11 studies encompassing almost 1 million people with COVID-19 and more than 6 million uninfected individuals showed that COVID-19 increased the risk of development of new-onset dementia in people older than 60 years of age.
Drops in IQ
Most recently, a new study published in the New England Journal of Medicine assessed cognitive abilities such as memory, planning and spatial reasoning in nearly 113,000 people who had previously had COVID-19. The researchers found that those who had been infected had significant deficits in memory and executive task performance.
This decline was evident among those infected in the early phase of the pandemic and those infected when the delta and omicron variants were dominant. These findings show that the risk of cognitive decline did not abate as the pandemic virus evolved from the ancestral strain to omicron.
In the same study, those who had mild and resolved COVID-19 showed cognitive decline equivalent to a three-point loss of IQ. In comparison, those with unresolved persistent symptoms, such as people with persistent shortness of breath or fatigue, had a six-point loss in IQ. Those who had been admitted to the intensive care unit for COVID-19 had a nine-point loss in IQ. Reinfection with the virus contributed an additional two-point loss in IQ, as compared with no reinfection.
Generally the average IQ is about 100. An IQ above 130 indicates a highly gifted individual, while an IQ below 70 generally indicates a level of intellectual disability that may require significant societal support.
To put the finding of the New England Journal of Medicine study into perspective, I estimate that a three-point downward shift in IQ would increase the number of U.S. adults with an IQ less than 70 from 4.7 million to 7.5 million – an increase of 2.8 million adults with a level of cognitive impairment that requires significant societal support.
Another study in the same issue of the New England Journal of Medicine involved more than 100,000 Norwegians between March 2020 and April 2023. It documented worse memory function at several time points up to 36 months following a positive SARS-CoV-2 test.
Parsing the implications
Taken together, these studies show that COVID-19 poses a serious risk to brain health, even in mild cases, and the effects are now being revealed at the population level.
A recent analysis of the U.S. Current Population Survey showed that after the start of the COVID-19 pandemic, an additional 1 million working-age Americans reported having “serious difficulty” remembering, concentrating or making decisions than at any time in the preceding 15 years. Most disconcertingly, this was mostly driven by younger adults between the ages of 18 to 44.
Data from the European Union shows a similar trend – in 2022, 15% of people in the EU reported memory and concentration issues.
Looking ahead, it will be critical to identify who is most at risk. A better understanding is also needed of how these trends might affect the educational attainment of children and young adults and the economic productivity of working-age adults. And the extent to which these shifts will influence the epidemiology of dementia and Alzheimer’s disease is also not clear.
The growing body of research now confirms that COVID-19 should be considered a virus with a significant impact on the brain. The implications are far-reaching, from individuals experiencing cognitive struggles to the potential impact on populations and the economy.
Lifting the fog on the true causes behind these cognitive impairments, including brain fog, will require years if not decades of concerted efforts by researchers across the globe. And unfortunately, nearly everyone is a test case in this unprecedented global undertaking.
Ziyad Al-Aly is Chief of Research and Development, VA St. Louis Health Care System and a Clinical Epidemiologist at Washington University in St. Louis.
TR says
Thank goodness. It explains why I feel that there is an abundance of people that seem to have lost their brain function of common sense. I have said for the past three years that to me it seems people have gotten stupid, which can not be fixed. So at least now I have something to blame it on.
DaleL says
Donald Trump in October 2020 had a severe case of COVID-19. He was hospitalized at Walter Reed for several days. President Joe Biden tested positive for COVID-19 in July 2022. He was reported to have mild symptoms. Mr. Biden has had at least one re-infection.
So to add (or rather subtract) this, Mr. Biden may have lost 3 + 2 = 5 IQ points. Mr. Trump may have lost upwards of 9 IQ points. (That could help explain why Mr. Trump once again, yesterday, mixed up Obama with Biden.) In addition, both Mr. Trump (77) and Mr. Biden (81) are old. Are these two REALLY the best candidates for the office of President?
A final thought, perhaps COVID is not the only virus that can result in damage to a person’s brain. Perhaps a severe infection with measles, mumps, etc. may have a similar outcome?
Ed P says
Hmmm….experts can not definitively pin point the origin. They can not definitively explain why some people never got Covid or if it is absolutely possible to get it multiple times if natural immunity existed(not vaccine generated).
The minimal information 2 years later surprises me. Yet we now have a study that “scientifically” claims that IQ s are negatively impacted?
Could not find anything that excluded increased drug/alcohol use during the 2 years people sheltered in fear. Did disinfectants that were sprayed everywhere, even on Amazon deliveries affect brain cells?. What about hand sanitizers? What about breathing more carbon dioxide because of masks, doubling and even tripling? What about breathing indoor air (poor quality) or lack of exercise?
Is Covid at fault or the response to Covid? Come on man! I’ll take a quart of the snake oil, please.
The dude says
Looks like you’re already well stocked in the snake oil department…
oldtimer says
How many times has Biden tested positive?
Michael J Cocchiola says
Hmmm… guess that explains the MSGS cult. But I think the brain loss is closer to “all”!
Sherry says
I’ll take the scientific analysis of an expert over the word of an indoctrinated “legend in his own mind”, anytime.
Ed P says
Sherry,
I’m surprised that you are qualified to call one Doctor a charlatan and another an expert based on two Flagler live articles.
Must be a California thang…
Pierre Tristam says
It’s not based on two articles, but on an American death toll approaching 1.2 million. Charlatan is an understatement. The man is closer to a Mengele.
Ed P says
A similar comparison made by Lara Logan comparing Anthony Fauci to Joseph Mengele was a career ending comment. Rather offensive, wouldn’t you agree?
Me thinkith you might be overstating Ladapo damage to Floridas population.
Here is his pedigree.
After immigrating to the United States from Nigeria, he earned a M.D. and a Ph.D in Health policy from Harvard University. He served as a professor of medicine at NYU before being tenured at the university of California, Los Angeles.
Your anecdotal evaluation of his performance as our surgeon general is ridiculous.
Pierre Tristam says
Logan was wrong: Fauci wasn’t a bogus doctor. Nothing anecdotal about Ladapo’s murderously ill-informed transformation of the quackery of “Frontier Doctors” into state health policy. The man has a few hundred, probably a few thousand, deaths on his hands. Mengele experimented with human life. Ladapo is doing nothing less. In that context, pedigrees are a pile of turd used to hide the morbid man behind them. (Mengele had a doctorate too.)
Sherry says
Thank you Pierre and Flaglerlive for inserting reasonable logic here. Unfortunately facts and credible analysis are lost on most of those indoctrinated to the alternate reality of the extreme right.
Samuel L. Bronkowitz says
It’s hard to be accurate about the number of deaths when people stop bothering to record covid infections and organizations like the CDC place the fiscal desires of the CEO of Delta ahead of public safety.
Laurel says
I don’t know, this sounds a bit off. I don’t see how anyone can determine what is affecting people, specifically, any more. Americans have a horrid diet, not even counting plastics and pesticides.
We went to a very popular coffee chain for a quick snack grab. It’s, I think, the third time I’ve been there since it opened up. People line up their cars around the block to get their super sugary coffees. I got a ham and Swiss croissant, and a passion tea. How they dare call what I got a “croissant” is beyond me. Totally nasty, tasteless goo! My passion tea was neither passion fruit nor tea. It was some chemical junk that came back up after two sips. To the garbage can it went! I see cars lined up around a building that is famous for its hamburgers, which also is nasty. Americans are addicted to salt, fat and sugar, and it’s all very planned by the corporations that run these chains.
Cross another place off my list.
I watch Bobby on FlavCity on YouTube. Today, we watched about how our oats and wheat are sprayed with Round Up to dry and kill the plants for easier harvesting. He recommends organic grains only.
How on Earth are we focusing in on COVID’s effect on the brain when we are filling our bodies, and brains, with excessive amounts of pure trash and poison? COVID has been deadly to millions, but focusing on it rather than what is killing many more seems a failure. Well, at least we know a lot about rats and mice.
DaleL says
Except for a small drop due to COVID, Americans live longer than ever. Pesticides have actually improved life and longevity. Plastics allow our food to be packaged more safely. Much of our food isn’t very nutritious, but compared with a century ago, very few people die of food borne illnesses.
COVID is just one of many viruses which can infect humans. By studying COVID’s effect on the brain, it is possible to gain some insight on the effects of other viruses. There was a time in America when southerners were labeled as slow, lazy and stupid. Many people, from Texas to Virginia, neglected their fields and children grew pale and listless. The cause was hookworm. Up to 40% of the population of the Southern US had hookworm.
There was a time in the US when gasoline contained lead. Where and when I grew up, houses were heated with coal. The air wasn’t always even safe to breath.
Laurel says
DaleL: And you find this junk fed to us virtuous? Coke Cola had real cocaine in it at one time. Should we have kept it? Micro plastics in you body is fine? Americans are in terrible shape, and I seriously question whether they will continue live longer lives.
Covid killed many people who were not in good shape to begin with.
Growing up in south Florida, we kept hearing a jingle “We all grew up on McArthur’s!” Yeah, we did, and it was milk from grass fed cows. We also ate Winn Dixie meat from cattle the company raised in pastures of grass. Now, if we want the same kind of products, we have to pay $7.00 bucks for a half gallon of grass fed cow milk, and a ton of cash for grass fed beef. Look at the difference of quality between the eggs that come in styrofoam cartons and eggs from chickens humanely raise free range. All this, just to get back to where we were.
Nancy N says
So by your logic, medicine should only be researching what is the top cause of death at any one time? So, no cancer research? No research into diseases like MS or arthritis?
Laurel says
Nancy: I have no idea how you got there. Jumping to conclusions? I’ll take science over religion and politicians any day.
I’m saying with all the pollution, plastics (we all have micro plastics in our systems now) and pesticides (organic is clearly better) where is the baseline for human health research? Why are Americans stuffing their bodies with the absolute trash the corporations are purposely getting people addicted to?
Salt, sugar and fat is doing what for you? How about making you less healthy so you require more drugs to stay alive?
jake says
This explains how Biden became President.
Laurel says
Jake: No, not really.
The dude says
But does having had COVID destroy cognitive ability anywhere near the same levels as watching Fox News, OAN, or Newsmax?
The answer is a resounding “NO”… clearly…
Sherry says
@dude. . . best snarky comment yet! Right On!
MeToo says
@Sherry….agreed!
Ray W. says
No one has mentioned the Flynn Effect.
While there are many critics, mainly due to the Flynn Effect’s potential impact on the imposition of the death penalty, and its concurring impact on those who wish to gain political power by advocating for the execution of the intellectually disabled among us (it is more difficult to upheld a verdict of death in a case involving the intellectually disabled), in 1984, Dr. J. R. Flynn published his analysis of multiple studies of I.Q. testing over multiple decades. He estimated that the norm was for the average American to drop 3.1 I.Q. points per decade.
In 2014, the National Library of Medicine published its analysis of 285 studies on the subject, dating from 1951. It estimates a drop of 2.3 I.Q. points per decade. Most of the studies are recent, as the issue has gained adherents over time.
The premise arose after the testing norms kept rising over time. In other words, our children, when taking the same tests we took, simply tested higher than we did, on average. The norm of 100 in 2004, if the NLM’s findings are accurate, would be 95.4 in 2024, after our children’s test results were averaged to 100. I.Q. tests are simply adjusted over time to maintain an average score of 100.
Yes, if either of our presidential candidates were to take today’s I.Q. tests, each would likely score far below (estimated at some 16.1, points below) the scores achieved by their great grandchildren.
Sherry says
Earth’s Population Statistics in Perspective – Interesting Trivia
The population of Earth is around 7.8 Billion.
For most people, it is a significant figure. However, if you condensed 7.8 billion into 100 persons, and then into various percentage statistics, the resulting analysis is relatively much easier to comprehend.
Out of 100:
11 are in Europe
5 are in North America
9 are in South America
15 are in Africa
60 are in Asia
49 live in the countryside
51 live in a city,
75 have mobile phones
25 do not.
30 have internet access
70 do not have the availability to go online
83 can read
17 are illiterate.
33 are Christians
22 are Muslims
14 are Hindus
7 are Buddhists
12 are other religions
12 have no religious beliefs.
26 live less than 14 years
66 died between 15 – 64 years of age
8 are over 65 years old.
If you have your own home, Eat full meals & drink clean water, Have a mobile phone, Can surf the internet, and have gone to college, You are in the minuscule privileged lot.
(in the less than 7% category)
Amongst 100 persons in the world, only eight live or exceed the age of 65!
If you are over 65 years old, be content & grateful Cherish life. Grasp the moment.
If you did not leave this world before the age of 64, like the 92 persons who have gone before you,
you are already the blessed amongst humankind.
Take good care of your health. Cherish every remaining moment.
If you think you are suffering memory loss, read on.
Anosognosia, very interesting:
In the following analysis, the French Professor Bruno Dubois, Director of the Institute of Memory and Alzheimer’s Disease (IMMA) at La Pitié-Salpêtrière – Paris Hospital addresses the subject in a rather reassuring way:
“If anyone is aware of their memory problems, they do not have Alzheimer’s.”
1. forget the names of families.
2. do not remember where I put some things .
It often happens in people 60 years and older that they complain that they lack memory. “The information is always in the brain, it is the “processor” that is lacking.”
This is “Anosognosia” or temporary forgetfulness.
Half of people 60 and older have some symptoms that are due to age rather than disease. The most common cases are:
– forgetting the name of a person,
– going to a room in the house and not remembering why we were going there,
– a blank memory for a movie title or actor, an actress,
– a waste of time searching where we left our glasses or keys.
After 60 years most people have such a difficulty, which indicates that it is not a disease but rather a characteristic due to the passage of years .
Many people are concerned about these oversights hence the importance of the following statements:
1.”Those who are conscious of being forgetful have no serious problem of memory.”
2. “Those who suffer from a memory illness or Alzheimer’s are not aware of what is happening.”
Professor Bruno Dubois, Director of IMMA, reassures the majority of people concerned about their oversights:
“The more we complain about memory loss, the less likely we are to suffer from memory sickness.”
Now for a little neurological test:
Only use your eyes!
1- Find the C in the table below!
OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO
OOOOOOOOOOOOOOOOOOOCOOOOOOOOOOO
OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO
OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO
OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO
OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO
2- If you found the C, then find the 6 in the table below.
99999999999999999999999999999999999999999999999
99999999999999999999999999999999999999999999999
99999999999999999999999999999999999999999999999
69999999999999999999999999999999999999999999999
99999999999999999999999999999999999999999999999
99999999999999999999999999999999999999999999999
3- Now find the N in the table below. Attention, it’s a little more
difficult!
MMMMMMMMMMMMMMMMMMMMMMMMMMMMNMM
MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM
MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM
MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM
MMMMMMMMMMMMMMMMMMMMMMMMMMMMMMM
If you pass these three tests without problem:
– you can cancel your annual visit to the neurologist.
– your brain is in perfect shape!
– you are far from having any relationship with Alzheimer’s.
We are truly blessed, So, share this with your over-55 friends, it can reassure them.
In any case, if you are over 65 and complaining about a few aches and pains, think again
…….. 92% of people didn’t even get that opportunity!!
So be pleased with your situation and be happy.
Laurel says
1.) 2, past center. One second.
2.) 4, 1. One second.
3.) 1, end. Two seconds.
Thanks! Feeling pretty good now! :D
Ray W. says
Thank you, Sherry.
MeToo says
Yes. Thank you Sherry.