Illustration: Kieran Blakey

The Nuance

The Latest Scientific Theories Around Covid-19 Brain Fog

Experts say the immune system’s reaction to SARS-CoV-2 could shift brain activity in ways that disrupt sleep-wake cycles

Elemental
Published in
6 min readOct 29, 2020

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Corey McPherson knows that he contracted SARS-CoV-2 back in March. He also knows that by late April, when he turned 36, he’d mostly recovered from his acute symptoms — his fever and pain and breathing problems.

But if you ask him now to recall that time, he says that there’s not a lot he could tell you. It’s as if a page has been ripped out of his memory’s notebook. “I don’t remember much about when I was actually sick with it,” he says. “There are one or two blips, but I have almost zero recollection of that time. I still forget a lot of things.”

McPherson lives in Detroit and works in IT. Pre-Covid, he exercised almost every day and was healthy. His mind was sharp. “I was the guy who remembered everything,” he says. “But my memory is horrible now.” He struggles sometimes to come up with simple words or to finish sentences, and he often feels disoriented. I often find myself in a dream-like state, and I have to snap back into reality,” he says. “At first I thought this was just a hiccup in my recovery, but now it’s been six months and it’s not getting better.”

“The brain fog is real,” he adds.

The term “brain fog” is ill-defined, but it’s one that more and more experts are using to describe a cluster of neurological symptoms that a lot of people who have had Covid-19 go on to experience for months following their initial infection. These symptoms include memory and concentration problems, as well as a general lack of sharpness. They also include headaches, poor sleep, anxiety, and other lingering symptoms that seem rooted in the brain.

“I don’t remember much about when I was actually sick with it. There are one or two blips, but I have almost zero recollection of that time. I still forget a lot of things.”

How common is post-Covid brain fog?

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Markham Heid
Elemental

I’m a frequent contributor at TIME, the New York Times, and other media orgs. I write mostly about health and science. I like long walks and the Grateful Dead.