Understanding how Covid-19 Affects the Brain

A couple of months into the pandemic, when scientists and physicians were still approaching Covid-19 primarily as a respiratory illnessDr. Igor Koralnik, chief of neuro-infectious diseases and global neurology at Northwestern Medicine, began seeing a new category of patients seek treatment at his neurology practice in Chicago. In addition to sharing similar neurological symptoms, they had something else in common: Each had Covid-19, but never fully recovered.

One after another, via both in-person and telehealth appointments, the patients described a set of neurological symptoms that included some combination of headache, dizziness, difficulty concentrating, memory problems, and, most frequently, cognitive dysfunction many referred to as “brain fog.” In addition to their frustration and unanswered questions, the patients had another shared experience: While most went through a few days or even weeks of acute illness, their symptoms never got severe enough to warrant a visit to the hospital.

Without proof of a hospital stay, many of these self-described Covid “long-haulers” — people with what researchers are now calling long-Covid or PASC (Post-Acute Sequelae of SARS-CoV-2 infection) — found themselves dismissed by doctors who didn’t believe that their mild cases could possibly have impacted their cognitive function. Koralnik, on the other hand, took a different approach, opening his Neuro Covid-19 Clinic in May 2020. He made the decision to see anyone who said they were dealing with post-Covid neurological symptoms, regardless of whether they were hospitalized, or ever tested positive for Covid-19 or antibodies. (The extremely limited availability of Covid tests in the spring of 2020 meant that many people were unable to get one — regardless of whether they had every known symptom.)

An expert in neuro-infectious diseases, Koralnik has years of experience researching and treating viral infections that result in neurological conditions — like encephalitis caused by the herpes virus, and Guillain-Barré syndrome developing in people infected with Zika. “There are dozens of viruses that cause neurological problems,” Koralnik tells Rolling Stone, “but nothing like what we’ve seen with the SARS-CoV-2 coronavirus.”

Recognizing the importance of not only providing his patients with clinical care but also learning about the longer-term effects of the virus on the brain, Koralnik immediately began researching this lesser-known aspect of Covid-19.

In October 2020, Koralnik and his team published their first findings, on the frequency and severity of neurological symptoms in patients hospitalized with Covid-19. Their second article — published on March 23rd in the Annals of Clinical and Translational Neurology — is the first study to report neurologic findings in long-Covid patients who were not hospitalized. Most notably, this research found that despite having mild cases of Covid-19, 85 percent of these patients reported experiencing at least four neurological symptoms that impacted their quality of life, and/or their cognitive abilities.

While it’s important to keep in mind that these are the findings of a single, relatively small study, it is a significant step toward recognizing the effects the virus can have on the brain. Here are a few of the study’s insights that can help expand our understanding of the neurological impact of Covid-19.

People with mild or severe cases of Covid-19 could see lingering effects 

According to Koralnik’s October 2020 article, approximately 80 percent of people hospitalized with Covid-19 experience neurological symptoms. While that finding is certainly alarming, this group of patients benefits from clinical acceptance of post-ICU cognitive effects — and have the hospital wristband (and records) demonstrating the severity of their illness. But non-hospitalized Covid-19 patients with lasting neurological difficulties had neither the research nor wristbands to make their case to doctors.

This new study changes that, providing evidence that those with even mild cases of Covid-19 could have lingering effects. The study’s participants were the first 100 eligible non-hospitalized long-Covid patients who sought treatment at the Neuro Covid-19 Clinic from May to November 2020. Their average age was 43, 70 percent were women, and 85 percent reported a minimum of four neurological symptoms. In other words, the severity of a person’s Covid-19 acute infection doesn’t predict whether they’ll experience long-lasting neurological difficulties. “Long-Covid [also] affects people who initially only had mild respiratory presentation of Covid-19 and did not require hospitalization for pneumonia,” Koralnik tells Rolling Stone. “Neurologic symptoms may persist for months and may adversely affect the quality of life and cognitive functions.”

There is a wide variety of neurological symptoms

Koralnik’s research also provides important insights into the types of symptoms long-Covid patients experience. “I was surprised by the high frequency of neurologic symptoms and their variety,” Koralnik explains. In the study, the most frequently reported symptoms related to brain function were brain fog (81 percent), headache (68 percent), numbness/tingling (60 percent), disorder of taste (59 percent), disorder of smell (55 percent), muscle pain (55 percent), dizziness (47 percent), pain (43 percent), blurred vision (30 percent), and tinnitus (29 percent).

There’s a connection between mental health and long-Covid

Prior to the release of the new research, the neurological impact of Covid had already made the news this week, following the March 18th death of Kent Taylor — the founder and chief executive of the Texas Roadhouse restaurant chain — at the age of 65. According to a statement from Taylor’s family, he died by suicide following a struggle with post-Covid symptoms, including severe tinnitus.

While there’s still much to learn about the link between long-Covid and mental illness, a few details are emerging. For example, 42 percent of the participants in Koralnik’s study reported having depression and/or anxiety prior to contracting Covid-19. “We were surprised by the number of patients who were suffering from depression/anxiety before their Covid-19 diagnosis, and this suggests a possible neuropsychiatric vulnerability to developing long-Covid,” Koralnik explains.

This presence of pre-Covid mental-health conditions or symptoms is something Dr. Anna Nordvig, a neurologist at Columbia University Irving Medical Center (CUIMC) and New York-Presbyterian Hospital, and the co-founder of the CUIMC Post-COVID “Brain Fog” Clinic, has observed among her patients as well.

“I am surprised how often I hear ‘yes’ when I ask about pre-Covid, ADHD-like tendencies and mood symptoms, because the patients I see in the clinic were functioning well pre-Covid — even if they had some underlying susceptibility, like mild, well-controlled anxiety or ADHD,” she tells Rolling Stone. “Perhaps [Covid] tests the weakest link. As a patient once said to me, ‘It goes for where you’re weakest and what you care about most.’”

In other cases, changes in mood or the presence of mental-health conditions may occur after a Covid-19 infection. A recent article published in Nature — which Nordvig co-authored, along with colleagues from Columbia University — details some of the psychiatric effects of long-Covid, including the development of anxiety, depression, obsessive-compulsive behaviors, and post-traumatic stress disorder in some patients. In her cognitive clinic, Nordvig says she has had patients report various changes in mood, “sometimes with passive suicidal thoughts in patients who had never before had them.”

Next up: Research into possible treatments 

While there is no cure for the neurological impacts of long-Covid, Nordvig says that there are treatments that doctors are now trying, based on patient-specific symptoms. This itself marks a promising shift from the challenges many long-Covid patients faced only a few months ago, when it wasn’t uncommon for health care professionals to dismiss the concept of long-Covid altogether — let alone attempt to treat it.

The pandemic is far from over, but looking back at the accomplishments of research conducted over the past year — including the development of multiple safe and effective Covid-19 vaccines — there are reasons to be cautiously optimistic about the possibility of future advancements. One is the unprecedented cooperation among many researchers to try to find solutions to the innumerable problems the pandemic has caused, affecting nearly every aspect of our lives.


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