By now I’ve taken care of hundreds of COVID patients and if I never see another person struggling in the ICU on a ventilator with that virus I’d be delighted. But as much as we want to forget all about this nasty little bug, I’m a little afraid it isn’t quite ready to forget about us. We’ve talked a lot about problem solving, thinking, and paying attention in these pages lately. It’s obvious that quick, accurate problem solving requires being sharp and mentally “out in front of the airplane.” There’s a big problem when we’re not. It happens; sometimes we’re operating in a haze of “brain fog“ that ties our perception and thinking process up in knots. What’s really a scary thought would be to put COVID and “brain fog” together in the same sentence. Details are only now emerging but I will say, without screaming that the sky is falling, COVID brain fog is a topic that sure is “trending” in the medical media and, unfortunately, seems to be another thing we’re finding out with this new virus. It’s something we are going to have to face up to since everyone at some point will be exposed to this virus and, as pilots, we have no margin for error up in the sky.
The last time we talked about brain fog I said it’s that feeling that your head is wrapped up in cotton and there’s a layer of insulation between you and the outside world so that things just aren’t penetrating into your brain right. It’s a real medical entity that psychologists call the “Syndrome of Brain Fogginess” (BFS). They define it as a “transient cognitive impairment manifesting slow thinking, difficulty focusing, confusion, lack of concentration, forgetfulness, or a haziness in thought processes, slurred speech and possible gait or coordination disturbances.” Those are almost the exact same words that researchers are using for the new COVID brain fog syndrome. Maybe it will come to be known as “COVID-BF” someday, although the official name that’s catching on now is “Neuro-COVID Syndrome.” Desai and coworkers from the Department of Neurology, All India Institute of Medical Sciences in Uttarakhand, India, wrote one of the most thorough reviews on Neuro-COVID Syndrome. They report it occurs in 8-25% of COVID patients regardless of the severity of the initial infection. Clinical signs of this COVID complication that they report include all the symptoms listed above and also a few others like headaches, anxiety, depression, generalized disorientation, confusion, seizures, and both cognitive and decision-making impairments.
Cognitive dysfunction secondary to COVID was detailed in another recent article, “Executive dysfunction following SARS-CoV-2 infection.” Peter Hall and his associates report that COVID-19 infection is associated with “executive decision making dysfunction among young and middle-aged adults.” They state that most of the decision-making areas affected were in the frontal cortex of the brain. He found that COVID patients had “significantly greater symptoms of cognitive dysfunction and thought disruption compared to statistically matched non-infected individuals.” There have been multiple similar peer-reviewed studies confirming these findings. In one similar investigation, “Neural Dysregulation Following Infection from SARS-CoV-2,” Anne Baker and her colleagues from Newcastle University Medical College in the UK confirm these other reports. They say that fatigue and thinking and cognitive disruption were common and had “a substantial impact on daily life.” They studied patients after even mild COVID infection and carried out a battery of behavioral and neurophysiological tests assessing all three parts of the nervous system, the central, peripheral, and autonomic nervous systems. Using sophisticated images and studies, they attributed this dysfunction to disruptive changes in the “decision making” part of the brain’s frontal cortex region. That’s the same executive decision making area pointed to in Hall’s study (above) and confirms their data.
Another recent study from the UK published in Nature also found anatomical changes in the brains of SARS patients with post-infection cognitive dysfunction. Gwen Douaud and coworkers have a paper titled “SARS-CoV-2 is associated with changes in brain structure” that identified “significant structural changes in brain scans of patients after SARS-CoV-2 infection compared to a matched control group.” The study was statistically well powered and that always enhances the validity of the data, with 785 participants including 401 individuals infected by SARS-CoV-2. The changes they identified were a reduction in gray matter thickness and brain tissue in the frontal cortex (again similar to the other studies) due to actual brain tissue damage, and an overall reduction in global brain size. Their study protocol eliminated the really sick patients who had spent time in the ICU. That further enhanced this study’s efficacy since it takes away one argument out there that these COVID neurological abnormalities were simply a manifestation of a generic post-serious-illness malaise, something we call “ICU psychosis.” They were also able to show with brain images that the degenerative spread of the disease gets into the front part of the brain through the nerve tracts from the nose called the olfactory pathways. The nasopharynx (nose and throat) is the primary source of intake of a respiratory infection and how we catch this bug in the first place. This finding makes good anatomical sense and would also explain the common symptom of sensory loss of taste and smell that many patients experience with COVID infection.
A recent publication by Joanna Hellmuth and coworkers at UC San Francisco report on the cause of these anatomical changes in the front part of the brain. They found that post-infection COVID brain fog is linked to biochemical changes in the central nervous system secondary to the severe inflammatory response this virus stirs up in our system. They found this out by doing "spinal tap" procedures to collect cerebrospinal fluid (CSF) from their patients. CSF is a protein-rich solution that surrounds the brain and spinal cord and was sampled to diagnose a number of central nervous system diseases. Patients with persistent cognitive impairment months after illness, even with those who had only a mild COVID-19 infection initially, have higher levels of multiple inflammatory markers in their cerebrospinal fluid (CSF). These high levels of inflammatory chemicals were found in the CSF in 77% of patients with cognitive impairment. Their finding that patients who had COVID but no cognitive impairments had normal CSF chemistry further supported the significance of the study. Discovering high levels of inflammatory markers in the spinal fluid of COVID patients is totally consistent with my and my colleagues' clinical experience with the illness. COVID patients don't succumb to a non-survivable viral infection; they die from an overwhelming inflammatory reaction caused by the virus that we call SIRS, "Systemic Inflammatory Response Syndrome." SIRS uncouples the body's regulatory chemistry and leads to shutdown of all the patient's body systems. It requires massive doses of anti-inflammatory medication (steroids) that is the mainstay of our current COVID treatment in the ICU. Putting all this together, these studies and our clinical experience treating COVID patients are consistent and point to a quantifiable and measurable inflammatory, biochemical and anatomical basis for COVID brain fog.
There’s more to the story. Cognitive dysfunction following COVID infections is part of a larger constellation of symptoms associated with this illness that can last for quite a while. These long-term complications have been lumped into a single entity now known as “long COVID.” The length of time symptoms are most likely to last ranges anywhere from 5 weeks to at least one year and maybe longer. There’s quality peer-reviewed evidence from multiple sources that long COVID can affect many organs besides the brain, including the heart, kidney, pancreas, and digestive system. Long COVID can be seen not only in patients who have been hospitalized or even sick enough to have been in an intensive care unit, but also in patients who have had less serious forms that did not require hospital admissions. The exact number of patients it affects in this way varies depending on inclusion criteria and definitions, but the consensus in the medical literature is in the range of 10-30% of post-COVID patients.
Returning to where I started with all this, it is very important for airmen to be aware of something that may feel like only minor and subtle changes in thinking and problem solving after having been sick for a while and be easy to dismiss. We’ve talked about checking up on yourself in the article on “Who Will Guard the Guardians,” and I’ll be the first to admit that it’s not easy to do, but if we don’t do it ourselves our friends in Washington surely will. The FAA is already tuned in to this issue and in several FAA Memoranda, the most recent dated October 27, 2021, AMEs are instructed to defer issuance of medical certification to airmen “experiencing ongoing residual signs and/or symptoms of confirmed COVID-19, which may include but are not limited to cardiovascular dysfunction, respiratory abnormalities, kidney injury, neurological dysfunction, psychiatric conditions (e.g., depression, anxiety, moodiness), or symptoms such as fatigue, shortness of breath, cough, arthralgia, or chest pain.” (The italics are mine to emphasize that the FAA is leaving a lot of room to interpret post-COVID symptoms up to AMEs.) The bottom line is that even “mild” COVID symptoms can sometimes lead to more serious decision-making impairment. Be on the lookout, don’t fly alone if you feel “foggy,” and don’t let yourself get into trouble. There are recent reports from Harvard Medical School that indicate this syndrome can get better with time and treatment, but be on guard and stay safe until your head clears up.