Once It Infects The Brain It Can Affect Anything
Another study supports the idea that COVID-19s attack on the brain is what makes the disease very severe.
A team of researchers, including senior study author Mukesh Kumar, a virologist specializing in emerging infectious diseases and assistant professor at Georgia State University, in Atlanta, infected the nasal passages of mice with the new coronavirus. This caused severe illness in the rodents, even after the infection had cleared from their lungs.
The scientists then analyzed levels of the virus in several organs, comparing the intervention group of mice with a control group, which had received a dose of saline solution instead of the virus.
The results published in the journal revealed that viral levels in the lungs peaked around day 3 after the infection, but levels in the brain persisted on days 5 and 6, coinciding with the symptoms being most severe and debilitating. The scientists also found that the brain contained 1,000 times higher levels of the virus than other parts of the body.
This may explain, the senior researcher says, why some people seem to recover after a few days and have improved lung function, only to then relapse and have more severe symptoms, some of which can prove lethal.
The brain is one of the regions where viruses like to hide, he continues, because unlike the lungs, the brain is not as equipped, from an immunological perspective, to clear viruses.
The Mental Health Effects Of Having Covid
While most people are dealing with more mental health issues than usual during the pandemic, the anxiety and stress that come with a Covid diagnosis is significant, even for those who recover.
Researchers wrote that the prevalence of mental health conditions among Covid survivors “reflects, at least partly, the psychological and other implications of a Covid-19 diagnosis rather than being a direct manifestation of the illness.”
Previous research from the same group at Oxford found that people who were diagnosed with Covid were more likely to be diagnosed with a mental health issue than people coping with other health issues during the pandemic. For example, those recovering from Covid-19 were twice as likely to be diagnosed with a mental health disorder as compared with someone who had the flu.
Almost 20% of Covid patients who recovered were diagnosed with a mental illnesses within three months.
Harrison, the lead author for both studies, said that the findings lay bare the need for mental health services for the large number of people who may be experiencing symptoms.
The Impact Of Underlying Inflammatory Conditions On Brain Symptoms
Some of the neurological symptoms associated with COVID-19 are commonly experienced by people with inflammatory arthritis and other inflammatory or autoimmune conditions.
For instance, fatigue is a disabling symptom in chronic inflammatory conditions, including rheumatoid arthritis , Sjögrens syndrome, lupus, and multiple sclerosis. So are problems with memory, concentration, and slowed thinking also termed cognitive dysfunction or brain fog.
On their own, these inflammatory conditions can also increase the risk for developing neurological symptoms. The risk of stroke is higher in most rheumatic diseases compared to that of the general population, particularly over the age of 50. RA and lupus increase the risk of stroke by up to 100 percent relative to the general population.
The takeaway: Its important to be mindful of your symptoms and report any new or worsening symptoms to your health care provider. They can advise you on what to do next based on your medical history.
For instance, given the reports of loss of smell and taste presenting as early symptoms of COVID-19, dedicated testing for the loss of smell and taste which can occur with diseases like Parkinsons and MS, as well as obesity, diabetes, and high blood pressure, all of which are comorbidities of chronic inflammatory conditions may offer the potential for early detection of COVID-19 infection, says Dr. Kuruvilla.
No Virus In Brain Cells
The study examined the brains of 41 patients with COVID-19 who succumbed to the disease during their hospitalization. The patients ranged in age from 38 to 97; about half had been intubated and all had lung damage caused by the virus. Many of the patients were of Hispanic ethnicity. There was a wide range of hospital length with some patients dying soon after arrival to the emergency room while others remained in the hospital for months. All of the patients had extensive clinical and laboratory investigations, and some had brain MRI and CT scans.
To detect any virus in the neurons and glia cells of the brain, the researchers used multiple methods including RNA in situ hybridization, which can detect viral RNA within intact cells; antibodies that can detect viral proteins within cells; and RT-PCR, a sensitive technique for detecting viral RNA.
Despite their intensive search, the researchers found no evidence of the virus in the patients brain cells. Though they did detect very low levels of viral RNA by RT-PCR, this was likely due to virus in blood vessels or leptomeninges covering the brain.
If theres any virus present in the brain tissue, it has to be in very small amounts and does not correlate with the distribution or abundance of neuropathological findings, Canoll says.
Infecting Neurons With Devastating Consequences
Other researchers have focused on how the new coronavirus infects neurons and damages brain tissue.
For example, a team led by Akiko Iwasaki, the Waldemar Von Zedtwitz Professor of Immunobiology and Molecular, Cellular, and Developmental Biology at the Yale School of Medicine, in New Haven, CT, used lab-grown, miniature 3D organ reproductions to analyze how SARS-CoV-2 invades the brain.
The study, which appears in the Journal of Experimental Medicine, showed that the new coronavirus was able to infect neurons in these lab-grown organoids and replicate itself by boosting the metabolism of infected cells. Simultaneously, healthy, uninfected neurons in the vicinity died as their oxygen supply was cut off.
The researchers also determined that blocking the ACE2 receptors prevented the virus from infecting the human brain organoids.
The scientists also analyzed the effects of SARS-CoV-2 on the brains of mice genetically modified to produce human ACE2 receptors. Here, the virus altered the brains vasculature, or blood vessels. This could, in turn, cut off the brains oxygen supply.
Furthermore, the mice with an infection that had spread to the brain had much more severe illness than those with an infection limited to the lungs.
Breaking Into The Brain
SARS-CoV-2 can have severe effects: a preprint posted last month compared images of peoples brains from before and after they had COVID-19, and found loss of grey matter in several areas of the cerebral cortex.
Early in the pandemic, researchers speculated that the virus might cause damage by somehow entering the brain and infecting neurons, the cells responsible for transmitting and processing information. But studies have since indicated that the virus has difficulty getting past the brains defence system the bloodbrain barrier and that it doesnt necessarily attack neurons in any significant way.
COVIDs toll on smell and taste: what scientists do and dont know
One way in which SARS-CoV-2 might be accessing the brain, experts say, is by passing through the olfactory mucosa, the lining of the nasal cavity, which borders the brain. The virus is often found in the nasal cavity one reason that health-care workers test for COVID-19 by swabbing the nose.
Even so, theres not a tonne of virus in the brain, says Spudich, who co-authored a review of autopsies and other evidence that was published online in April.
But that doesnt mean it is not infecting any brain cells at all.
Astrocytes are star-shaped cells in the central nervous system that perform many functions, including providing nutrients to neurons.Credit: David Robertson, ICR/SPL
What Helps With Treating Brain Fog Caused By Covid
As of now, the best treatment for brain fog caused by COVID-19 is to adopt healthy habits. The following tips may help boost your mental function if youre dealing with ongoing brain fog.
Researchers are continuing to look at the potential benefit of steroids for reducing inflammation of the brain that may contribute to cognitive changes.
The Science Behind How The Coronavirus Affects The Brain
New research could help explain why thousands of Covid-19 survivors are facing debilitating neurological symptoms months after initially getting sick. WSJ breaks down the science behind how the coronavirus affects the brain, and what this could mean for long-haul patients. Illustration: Nick Collingwood/WSJ
News moves fast, and there’s not always time to untangle the complex forces driving the day’s biggest stories. WSJ Explains breaks down big market moves, business and economic trends, and scientific developments to help you stay ahead of the curve.
Who Is At Risk Of Developing Brain Fog
Sarah A. Kremen, MD
Scientists don’t yet know who is likely to suffer from post-COVID-19 brain fog. However, there may be a link between the condition and anosmia during active infection.
“A virus can enter the nasal passages where it can then access nerves that lead into the brain. When these neurons are affected, the resulting conditionfrom coronavirus or any other virusis anosmia,” says Dr. Sarah A. Kremen, director of the Neurobehavior Program at the Jona Goldrich Center for Alzheimer’s and Memory Disorders. “Once the virus that causes COVID-19 reaches the olfactory bulb, it can travel long the olfactory pathways to other places in the brain.
While early studies don’t show any correlation between severity of disease and long-hauler symptoms such as brain fog, it makes sense that a brain starving for oxygen is likely to become compromised. Everything from poor heart and lung function to the social isolation caused by COVID-19 can affect cognitive processes. Treatments for COVID-19, including sedation, intubation and various medications, may also come with cognitive side effects.
“But plenty of patients get COVID-19, recover well and then a month or two later develop cognitive symptoms, such as slow thinking, difficulty concentrating and fatigue,” says Dr. Kremen. So, even patients who had mild disease and recovered seamlessly may still develop post-COVID-19 brain fog.
Subtle Cognitive Effects Of Covid
It is clear that COVID can cause brain damage by direct infection , by strokes, and by lack of oxygen. It is also clear that when patients experience severe illness requiring an ICU stay, brain damage is highly likely to occur, and its effects are typically obvious. But what if the COVID illness is not so severe? Can brain damage still occur?
A Chinese group of doctors and researchers examined several aspects of cognitive function in 29 individuals who were thought to have fully recovered from COVID infection. They found persistent impairment in sustained attention the ability to attend to important information for as long as it is relevant.
How Does Coronavirus Affect The Brain
Patients with COVID-19 are experiencing an array of effects on the brain, ranging in severity from confusion to loss of smell and taste to life-threatening strokes. Younger patients in their 30s and 40s are suffering possibly life-changing neurological issues due to strokes. Although researchers dont have answers yet as to why the brain may be harmed, they have several theories.
Critical care physician and neurointensivistRobert Stevens, M.D., who is the associate director of the Johns Hopkins Precision Medicine Center of Excellence for Neurocritical Care, has been tracking cases at Johns Hopkins in which patients with COVID-19 also have neurological problems. And, thanks to a new research consortium of more than 20 institutions, including the University of Pittsburgh Medical Center, New York University, Johns Hopkins and health systems in Europe, researchers, including Stevens, are using imaging and tests of blood and spinal fluid to understand how the coronavirus operates so they can prevent and treat effects on the brain.
Stevens explains some of the prevailing scientific theories.
For Survivors Of Severe Covid
What follows is a snapshot of the fast-evolving understanding of how the virus attacks cells around the body, especially in the roughly 5% of patients who become critically ill. Despite the more than 1000 papers now spilling into journals and onto preprint servers every week, a clear picture is elusive, as the virus acts like no pathogen humanity has ever seen. Without larger, prospective controlled studies that are only now being launched, scientists must pull information from small studies and case reports, often published at warp speed and not yet peer reviewed. We need to keep a very open mind as this phenomenon goes forward, says Nancy Reau, a liver transplant physician who has been treating COVID-19 patients at Rush University Medical Center. We are still learning.
How Covid And Other Viruses Affect Your Brain
In addition to the hallmark symptoms of Covid infection, such as fever, cough and shortness of breath, 25% of people experience symptoms related to their brain and nervous system, including dizziness, headache, debilitating fatigue and “brain fog” or cognitive impairment, which is trouble remembering, learning and concentrating. While symptoms tend to go away once someone recovers, some Covid survivors experience lasting long-term effects.
At this stage, researchers aren’t sure what the exact physiological mechanism is that’s driving the neurological and cognitive symptoms. One possible explanation? A study in the New England Journal of Medicine examined brain tissue from people who died from Covid and noticed a combination of inflammation and leaking blood vessels in the brain.
“Covid-19’s many neurological symptoms are likely explained by the body’s widespread inflammatory response to infection and associated blood vessel injury not by infection of the brain tissue itself,” Dr. Francis Collins, director of the National Institutes of Health, wrote in a blog post on Jan. 14.
Covid also seems to have a stronger effect on people’s neurological and mental health than other respiratory conditions: In the new study, there was overall a 44% greater risk of neurological and mental health diagnoses after Covid-19 than after flu, and a 16% greater risk after COVID-19 than with respiratory tract infections.
Therapy Used Around The World
There are no current treatments for brain fog attributed to COVID-19. But a new clinical trial at UAB is testing a proven rehabilitation method with a record of success in restoring lost function. Known as Constraint-Induced Therapy , it was developed by Edward Taub, Ph.D., University Professor in the Department of Psychology and director of the CI Therapy Research Group, in collaboration with colleagues at UAB. CI is used around the world to help patients regain limb function and language abilities after stroke.
Studies in France and the United States reveal that a third of patients hospitalized with COVID-19 have experienced memory loss and other cognitive difficulties in the months after their recovery. This brain fog can be debilitating. It feels as though I am under anesthesia, one patient said.
CI Therapy also is used to treat patients with traumatic brain injury, multiple sclerosis and cerebral palsy, and with anoxial and other brain damage in pediatric patients.
Individuals who think they can benefit are welcome to contact the project directly at 205-934-9768 or learn more about the study at .
Some 97% of the thousands of stroke patients who have taken part in CI Therapy have seen meaningful improvement, and the average patient uses his or her affected limb five times more post-therapy than pre-therapy.
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The Next Health Crisis
Schultz is hopeful that many people experiencing persistent cognitive issues from COVID-19 will eventually improve. Many stroke and traumatic brain injury patients experience spontaneous recovery, in which the brain heals itself within three to six months.
But others worry that cognitive issues caused by COVID-19 may lead to dementia. At the Alzheimers Association International Conference in July, scientists presented research showing that hospitalized COVID-19 patients had similar blood biomarkers, neurodegeneration, and inflammation to those with Alzheimers disease. The research has not yet been peer-reviewed.
Heather Snyder, vice president of medical and scientific relations at the Alzheimer’s Association, cautions that the findings dont necessarily mean someone who gets COVID-19 is more likely to develop Alzheimers or another type of dementia. Were still trying to understand those associations, she says.
For now, there are no specific treatments for COVID-related brain fog, memory loss, and other cognitive effects. Instead, doctors are using cognitive therapy, occupational therapy, or speech-language pathology to treat symptoms. Many studies, like the NIH one, are trying to understand the underlying mechanisms of cognitive dysfunction in long COVID patients in hopes of identifying potential treatments.
We and others are collecting anecdotal data from patients on what has helped them, but we are far from definitive therapeutics, Frontera says.
How Quickly Do The Impaired Senses Return
For most people, smell, taste and chemesthesis recover within weeks. In a study published last July, 72% of people with COVID-19 who had olfactory dysfunction reported that they recovered their sense of smell after a month, as did 84% of people with taste dysfunction. Claire Hopkins, an ear, nose and throat consultant at Guys and St Thomas Hospital in London, and her colleagues similarly observed a speedy return of the senses: they followed 202 patients for a month, and found that 49% reported complete recovery over that time, and a further 41% reported an improvement.
Can dogs smell COVID? Heres what the science says
But, for others, the symptoms are more serious. Some people whose senses do not return right away improve slowly over a long period and this can have consequences, says Hopkins. As a person regains their sense of smell, odours often register as unpleasant and different from how they remembered them, a phenomenon called parosmia. Everything smells rancid to these people, says Hopkins, and the effect can last for months. This might be because the olfactory sensory neurons are rewiring as they recover, she says.
Other patients remain fully anosmic for months, and it isnt clear why. Hopkins suggests that, in these cases, the coronavirus infection might have killed the olfactory sensory neurons.
Protect Yourself From Getting Covid
Avoiding contact with COVID-19 is key to safeguarding your health. Its important to do all the things youve likely already been doing to reduce the chance of getting or spreading the virus:
- Get a COVID-19 vaccine when it is available to you
- Wear a mask that covers your nose and mouth. This will protect yourself as well as others.
- Practice social distancing. For now, experts say you should assume that everyone you encounter in your daily life could be infected with the coronavirus as many as half of the people who test positive for the virus have no symptoms and, according to new , more than half of transmission comes from asymptomatic people. This makes it very important to stay at home if possible avoid gatherings and non-essential trips and to keep at least six feet apart from people who arent in your household in both indoor and outdoor spaces.
- Wash your hands frequently with soap and water for at least 20 seconds or use hand sanitizer with at least 60 percent alcohol.
What This Means For You
Patients diagnosed with and recovering from COVID-19 should remain aware of possible neurological impacts of the virus. Talk to your doctor about possible steroid treatment and monitor your symptoms if you experience neurological effects.
It’s also important to also consider the mental health tolls you might encounter as you adjust to your body’s changes. Establish a support network and reach out for help as you navigate your health journey.
The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.
Why Do People With Covid
Although the mechanisms are not fully understood, there is an emerging consensus that smell loss occurs when the coronavirus infects cells that support neurons in the nose.
When researchers first identified smell loss as a symptom of COVID-19, they were worried that the virus was infecting the odour-sensing neurons in the nose that send signals to the olfactory bulb in the brain and that the virus could therefore access the brain. However, post-mortem studies of people who had had COVID-19 have shown that the virus rarely reaches the brain.
A team led by Sandeep Robert Datta, a neurobiologist at Harvard Medical School in Boston, Massachusetts, has instead found that cells that support sensory neurons in the nose known as sustentacular cells are probably what the virus is infecting.
How COVID-19 can damage the brain
Datta and his colleagues zeroed in on sustentacular cells because SARS-CoV-2 attacks by targeting a receptor called ACE2 on the surfaces of cells, and sustentacular cells have many such receptors. Olfactory sensory neurons do not. This suggests that the coronavirus infects the support cells, leaving the neurons vulnerable and deprived of nutrients.
Persistent Neurological Problems In Survivors
Goldman says that more research is needed to understand the reasons why some post-COVID-19 patients continue to experience symptoms.
The researchers are now examining autopsies on patients who died several months after recovering from COVID-19 to learn more.
They are also examining the brains from patients who were critically ill with acute respiratory distress syndrome before the COVID-19 pandemic to see how much of COVID-19 brain pathology is a result of the severe lung disease.
Effect On The Brain Explains Loss Of Smell
Dr. de Erausquin recently published a along with colleagues, including senior author Dr. Sudha Seshadri, a professor of neurology at the same institution and director of the universitys Glenn Biggs Institute for Alzheimers and Neurodegenerative Diseases.
The basic idea of our study is that some of the respiratory viruses have affinity for nervous system cells, Prof. Seshadri explains. She adds, Olfactory cells are very susceptible to viral invasion and are particularly targeted by SARS-CoV-2, and thats why one of the prominent symptoms of COVID-19 is loss of smell.
Olfactory cells are concentrated in the nose. Through them, the virus reaches the olfactory bulb in the brain, which is located near the hippocampus, a brain area involved in short-term memory.
The trail of the virus, when it invades the brain, leads almost straight to the hippocampus, explains Dr. de Erausquin. That is believed to be one of the sources of the cognitive impairment observed in COVID-19 patients. We suspect it may also be part of the reason why there will be an accelerated cognitive decline over time in susceptible individuals.
In their paper, the scientists refer to existing evidence that makes them particularly wary of SARS-CoV-2s impact on the brain. For example, researchers have found that:
The aim is to understand how having COVID-19 increases the risk, severity, and progression of neurodegenerative conditions, such as Alzheimers, or psychiatric conditions, such as depression.