COVID-19 patients are developing ‘brain fog.’ But what does that mean?

Christina Sutton was diagnosed with COVID-19 in July. Although she tested positive for the virus, she had very few symptoms. But even after those went away, Sutton still experienced concentration and memory problems.

“I would describe it as like a waking dream,” said Sutton. “You’re there, but you’re not fully connecting.”

To many who've had COVID-19, Sutton’s experience may sound familiar. COVID-19 “long haulers,” or people who experience some symptoms of the disease for months, often refer to their prolonged “brain fog” — this same sense of confusion.

As the world nears eight months of the COVID-19 pandemic, it's becoming clear that a portion of the over 44 million people worldwide who have become sick with the virus are not fully recovering. These people, some of whom have been sick since the very start of the pandemic, sometimes complain of breathlessness, weakness, rashes, and heart palpitations. One of the most common symptoms among long-haulers is persistent brain fog. As the months wear on, some have started to suspect that some of their symptoms might never subside. But for millions of other people with chronic illnesses, some of which seemed to have began with infections, constant brain fog is already their reality. Now, they're hoping that this global pandemic will draw attention to a condition that has so drastically affected their lives.

Sutton is one of these people, although she says COVID-19 has made her brain fog even worse. Now in her early thirties, she started experiencing brain fog as a child as the result of a genetic condition — a hypermobility spectrum disorder. These disorders affect connective tissues like tendons and ligaments. People with these disorders tend to be extremely flexible, dislocate limbs easily, and experience chronic joint pain, in addition to other symptoms.

One of these symptoms is brain fog, and it's one of the least understood. It shows up in other chronic illnesses, too, from fibromyalgia to arthritis.

“Brain fog” is not a medical term — it’s a colloquial name for a collection of cognitive symptoms like confusion, trouble focusing, and loss of memory or slow recall, said Dr. Costantino Iadecola, a neurologist who directs the Feil Family Brain and Mind Institute at Weill Cornell Medical School. Patients often say “they cannot concentrate, they cannot remember as well, they feel like they can’t do anything,” he said.

In August, Iadecola published an article reviewing the effects COVID-19 appears to have on the nervous system, including the brain. Some of those with the virus can experience neurological symptoms, from minor ones like loss of taste and smell to serious complications like strokes, he said.

Still, researchers don't understand how this happens, said Iadecola. It’s not clear if the virus directly affects the brain, or if these effects indirectly result from other symptoms or complications. For instance, oxygen deprivation or kidney failure during severe illness can cause a person to become delirious, confused, and sometimes violent in a condition called encephalopathy. Both of these complications can occur in severe cases of COVID-19.

“The bottom line is that there is not enough data to make a definitive statement about how this disease works,” said Iadecola.

Cases of “brain fog” after milder cases of COVID-19 are even more baffling, he said. Other serious coronaviruses, like SARS and MERS, can get into the brain and cause long-term cognitive effects. But these viruses are more severe, and it’s not clear yet whether COVID-19 will have the same degree of long-term effects.

Iadecola said it’s not unheard of for a virus or any major health event to have lingering effects like brain fog. In fact, chronic fatigue syndrome, or myalgic encephalomyelitis (ME) may be triggered by an infection. The symptoms of ME seem to be similar to those of COVID-19 long-haulers, leading some chronic illness patients and researchers to suspect it can cause a similar chronic condition. Patients with ME experience extreme tiredness, chronic pain, and brain fog. Many can't work or even leave their homes, and in many cases, the cognitive effects of the disease can be one of its most debilitating symptoms.

“Long haul COVID-19 individuals who are developing some of the same symptoms [as ME] are giving more publicity to this illness," said Maureen Hanson, the director for the Center for Enervating Neuroimmune Disease at Cornell University.

Even so, it’s unclear what really causes ME, let alone its brain fog. Hanson is the senior author of two recent studies, one published in December 2019 and the other in October, supporting a growing body of research that have found that people with ME have differences in their cytokines, the signaling molecules in the immune system that are also responsible for the extreme immune reaction in COVID-19 called a “cytokine storm.” Although ME patients don’t have the same huge increase in cytokines that this immune reaction elicits, Hanson says it is a sign that the immune system is malfunctioning in some way.

Hanson says it’s possible that these immune system effects could have something to do with ME’s cognitive symptoms. “We do have immune cells in our brain,” she said. In some cases, she said, ME patients have inflammation in their brain, and it’s possible that an abnormal immune system could contribute to that. But she said without more research, it’s hard to say.

Jaime Seltzer, director of Scientific and Medical Outreach for the organization ME Action, has dealt with brain fog since she developed ME herself in 2014, although she has never had COVID-19. She says that for her it's one of the most frustrating parts of having ME. She frequently struggles to recall words, even though she has a good vocabulary. She also says that when her brain fog was worse, her memory was so bad that she would leave post-its all over her house to remind herself to complete daily tasks.

But Seltzer says that her brain fog has improved. Through trial and error, she’s found things like dietary supplements that seem to help, along with learning to pace herself and conserve her energy. But she knows that isn’t the case for so many with ME and brain fog. While Seltzer appreciates how important research like Hanson’s on the nature of ME is, she’d love to see more research into palliative care and treatment. Hanson herself agrees.

“I certainly would like to see drug development” she said. “Right now, there is no FDA approved drug for this illness.”

There's also no specific treatment for brain fog in other chronic health conditions. Endometriosis, which causes tissue like that which lines the uterus normally to accumulate in other areas of the body, is sometimes associated with brain fog. There's research to suggest that people with endometriosis also have abnormal immune responses. There’s also research that shows more people with endometriosis have depression, which can contribute to brain fog. It's also unclear if brain fog in different conditions is actually the same, since brain fog is a generic term that can refer to a whole host of cognitive symptoms.

Nevertheless, Seltzer hopes that the renewed attention on it due to COVID-19 will lead to more research on its role in chronic health conditions. But she also emphasized that of course, the pandemic is a great tragedy, as is the fact that it could lead to chronic illness for a huge number of people.

“My first thought is not, yay research,” Seltzer said. “It's, oh no, these people who won't be able to have a job, these people who won't be able to think straight, these people whose families are not going to understand.”

Christina Sutton feels similarly. While her background is in theatrical management, she realized long before getting COVID-19 that she wouldn't be able to sustain a demanding career in theater. Eventually, she was also forced to step away from jobs in the corporate world. Now, she’s about to start graduate school for art therapy, hoping that this new career will be one she can cope with. Sutton said that ultimately what she hopes for is understanding of how serious brain fog can be. Brain fog symptoms are too often dismissed, she said, even by doctors.

“They can change the entire direction of your life,” she said.

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