It is clear that SARS–CoV-2 virus affects the nervous system in the acute stage. Now, according to experts at the most recent meeting of the American Academy of Neurology —including Dr. Anthony Fauci — we must turn our attention to the longer-term impact of the disease.

“We’re going to look back at this and say that we’ve lived through history, but we’re not through with it yet,” Fauci said. “As we get to the overwhelming majority of the population vaccinated, we’re going to see a rather strong turning towards what you would consider much more normal than what you and I are living through right now.”

But, even as this new normal emerges, many are still struggling with long-term impacts of the disease.

More than a year into the pandemic, the National Institute of Health coined the term post-acute sequelae of COVID-19 (PASC) and patients experiencing long-lasting COVID-19 are being referred to as “long-haulers.” Neurological symptoms of this include brain fog, sleep disorders, dysautonomia, and fatigue.

“Clearly the nervous system takes a hit,” said Dr. Walter Koroshetz during the panel discussion. “The big question is what are the long-term consequences?”

We know very little about the biological underpinnings of the more chronic form of COVID, he said, but we already know that “neurologists have to play a really important role in trying to get at the bottom of this problem.”

Triggers for Neurological Disease

One of the most common long-haul symptoms is fatigue. It’s similar to what patients with chronic fatigue syndrome, or myalgic encephalomyelitis, experience, according to Koroshetz and Fauci. Until now, chronic fatigue syndrome has been very challenging to diagnose and treat.

“We’ve been chasing myalgic encephalomyelitis without ever knowing what the etiologic agent was,” Fauci said. “Now, we have an absolutely well-identified etiologic agent.”

This means that further study can help neurologists not only treat post-acute COVID, but also chronic fatigue syndrome, Koroshetz said.

The experts also cited a recent study in The Lancet Psychiatry that followed patients six months after COVID-19 diagnosis. It showed an increased incidence of other neurological conditions such as stroke, dementia, and Parkinson’s disease.

In these cases, the SARS–CoV-2 virus may be acting as a trigger for the later development of neurodegenerative disease, similar to that seen with Parkinson’s disease and influenza, according to the panelists.

How Long is Long-Term?

Dr. Igor Koralnik, who also spoke at AAN, has been studying COVID-19 long-haulers at Northwestern Medicine. His patient follow-up has only gone as far as about nine months since symptom onset.

“What we want to know is how long is long-COVID?” he said. “I think it’s going to take decades before we are able to answer this question.”

One concern is that patients with long-lasting neurological sequelae like brain fog may be more at risk for developing later or accelerated onset dementia. It will take years to know for sure, Koralnik said, since diseases like Alzheimer’s may not develop until a patient is in their 70s and 80s.

While it is still too early to know the ultimate trajectory of the virus, these experts all agreed that even if the incidence of long-term neurodegenerative conditions is low, neurologists have an important task before them.

“It could be below 10 percent,” Koroshetz said. “But given the fact that there are so many millions infected, that’s going to be a lot of people.”