COVID-19 and the Brain (Part 1 of 2) The Symptoms – From Typical to Severe
While scientists around the world are working day and night to develop treatments and vaccines for COVID-19, we are still discovering new ways that the coronavirus (officially known as SARS-CoV-2) affects different parts of the body, and the brain and overall nervous system are certainly included. Here, we summarize what's been reported regarding COVID-19's impact on the brain and what it means for you. Of course, there is more we will learn in the future, but this is what we know now.
In this 2-part series, you will learn:
Part 1 TODAY
- The typical effects of COVID-19 on the brain
- Why the loss of smell?
- And the severe symptoms
Part 2 COMING NEXT
- How neurological symptoms of COVID-19 compare with the common cold and flu
- How the immune system and inflammation are involved
- How your diet could help: nutrients to fortify your immune system and preserve brain health
So, What Are the Typical Effects of Coronavirus on the Brain?
Medical reports from different parts of the world are painting a picture of brain and neurological symptoms, the most typical of which are headache, dizziness, numbness, agitation, and loss of smell and/or taste. Three recent studies highlight these symptoms: in California, France, and China.
- California: One study of 59 people from the Department of Surgery and Division of Otolaryngology-Head and Neck Surgery at the University of California San Diego School of Medicine found 68% of COVID-19 patients experienced loss of smell, while 71% reported a loss of taste. Patients in this study reported that these symptoms subsided within 2-4 weeks. (1) Some high-profile people experiencing this loss of smell include NBA Utah Jazz center Rudy Gobert and Rita Wilson, the wife of Tom Hanks.
- France: A recent study at the Strasbourg University Hospital in France investigated the neurological symptoms of 58 hospitalized COVID-19 patients. About 70% of patients experienced agitation and 45% had confusion. (2)
- China: An early study of 214 COVID-19 patients from the Department of Neurology at Union Hospital in Wuhan, China found that 33.6% of patients experienced some neurological symptoms. The most common among these symptoms were headache and dizziness, as well as an altered or lost sense of smell and taste. (3)
For additional information on symptoms, the Centers for Disease Control (CDC) is a good place to go, which recently added neurological symptoms to the list of COVID-19 symptoms on its website.
Why the Loss of Smell and Taste?
Since the loss of smell is proving to be a very common symptom of COVID-19, it has caught the attention of some popular press outlets, like The New York Times and The Washington Post. A team at Harvard Medical School recently investigated this. (4)
First, some background: the olfactory epithelium is a part of the nose that contains cells for detecting and processing odors. Among these cells are what scientists call receptor cells, support cells, and stem cells that could be targeted and killed by coronavirus. The Harvard study found that the virus may be most likely to attack support cells, which are the cells that remove harmful toxins. You can think of support cells as an air filter in your car. They are key components that protect the “engine" from harmful substances to keep the whole system running well.
A study with a similar coronavirus, SARS, indicates that the virus may infiltrate the olfactory bulb, the part of the brain that receives information about odors detected by receptors in the nose, also inhibiting the processing of smell. (Unfortunately, the loss of smell is often accompanied by a loss of taste, as smell is crucial for processing taste. If you cover your nose while eating, you’ll find you cannot taste your food very well.) After reaching the olfactory bulb, the SARS virus can then infect other parts of the brain, where it can cause a variety of neurological effects. (5) It is not yet clear by which of these mechanisms COVID-19 causes a loss of smell and taste, but scientists are following some quality leads.
Severe Brain Responses Related to COVID-19
Serious neurological symptoms of COVID-19 include encephalopathy (see box), altered consciousness, seizures, stroke, confusion, and hallucinations. They are more common in those who are more vulnerable to the coronavirus, including those over the age of 65 and those with pre-existing health conditions, such as diabetes, respiratory conditions, and cardiovascular disease.
Medical reports and case studies from the field illustrate manifestations of severe brain responses to COVID-19, including:
- A senior male: In a unique case in Florida, a 74-year-old man who tested positive for COVID-19 experienced encephalopathy. This patient had numerious pre-existing conditions including Parkinson's Disease, COPD, and cardioembolic stroke. Upon hospitalization, the patient had a headache and altered mental status. During his time in the hospital, his neurological symptoms worsened, and he became nonverbal and unable to follow commands. (7)
- A mid-life female: A 58-year-old female with no reported pre-existing conditions also experienced encephalopathy as a result of COVID-19. This patient presented with altered mental status and significant memory loss. The woman was diagnosed with acute necrotizing encephalopathy (ANE), which is a rare complication of viral infections that is associated with a strong immune response in the brain and results in lesions in several brain areas, representing dead and dying neurons. Brain scans indicated significant damage to the thalamus and medial temporal lobes of the brain. (8)
- Patients in France: Several patients from the study mentioned earlier in France also presented with more severe neurological symptoms. (2) Following MRI scans, 19% had encephalopathic features, including hypoperfusion in the brain (which results from reduced blood flow). A couple of patients presented with cerebral ischemic stroke as a result of COVID-19. (2)
- Also, some patients of COVID-19 have reported seizures and impaired consciousness, an altered state of wakefulness and or awareness, due to the damage to the brain (for example, similar to a concussion, you may be confused and not know where you are or what happened). (9)
So, to conclude this part of the series, whether the symptoms be not-so-good, bad or ugly, here’s what the research suggests so far: COVID-19 can indeed impact the brain in numerous ways. We're still learning by what mechanisms this occurs. Fortunately, early studies suggest that for most patients, the symptoms we discussed above are temporary and subside as the body recovers from infection, usually within several weeks. (1)
In Part 2, we'll describe to you how COVID-19 compares with the common cold and flu, how the immune system is involved, and how you can take action through diet.
In good health,
The NeuroReserve Research Team
Article keywords: coronavirus, COVID-19, brain, symptoms, immune system, inflammation, what food is good for the brain, brain health diet
- Yan CH, Faraji F, Prajapati Bs DP, Boone CE, Deconde AS. Association of Chemosensory Dysfunction and Covid-19 in Patients Presenting with Influenza-like Symptoms. Int Forum Allerg Rhinol (accepted manuscript). (2020). doi:10.1111/alr.22579
- Helms J, Kremer S, Merdji H, et al. Neurologic Features in Severe SARS-CoV-2 Infection. N Engl J Med (accepted manuscript). (2020). doi:10.1056/NEJMc2008597
- Mao L, Jin H, Wang M, et al. Neurologic Manifestations of Hospitalized Patients With Coronavirus Disease 2019 in Wuhan, China. JAMA Neurol (accepted manuscript). (2020). doi:10.1001/jamaneurol.2020.1127.
- Brann D, Tsukahara T, Weinreb C, Logan DW, Datta SR. Non-neural expression of SARS-CoV-2 entry genes in the olfactory epithelium suggests mechanisms underlying anosmia in COVID-19 patients. bioRvix (preprint report). (2020). doi:10.1101/2020.03.25.009084
- Netland J, Meyerholz DK, Moore S, Cassell M, Perlman S. Severe Acute Respiratory Syndrome Coronavirus Infection Causes Neuronal Death in the Absence of Encephalitis in Mice Transgenic for Human ACE2. Journal of Virology. 82, 7264-7275 (2008). doi:10.1128/jvi.00737-08
- Office of Communications and Public Liaison, National Institute of Neurological Disorders and Stroke, National Institutes of Health. Encephalopathy Information Page: National Institute of Neurological Disorders and Stroke (NINDS). Published 2010. http://www.ninds.nih.gov/disorders/encephalopathy/encephalopathy.htm
- Filatov A, Sharma P, Hindi F, Espinosa PS. Neurological Complications of Coronavirus Disease (COVID-19): Encephalopathy. Cureus. 12 (2020). doi:10.7759/cureus.7352
- Poyiadji N, Shahin G, Noujaim D, Stone M, Patel S, Griffith B. COVID-19-associated Acute Hemorrhagic Necrotizing Encephalopathy: CT and MRI Features. Radiology (accepted manuscript). (2020). doi:10.1148/radiol.2020201187
- Wu Y, Xu X, Chen Z, et al. Nervous system involvement after infection with COVID-19 and other coronaviruses. Brain Behav Immun (accepted manuscript). (2020). doi:10.1016/j.bbi.2020.03.031