The Atlantic has an article entitled “One of Long COVID’s Worst Symptoms Is Also Its Most Misunderstood” that covers brain fog.
Long-haulers with brain fog say that it’s like none of the things that people—including many medical professionals—jeeringly compare it to. It is more profound than the clouded thinking that accompanies hangovers, stress, or fatigue. For Davis, it has been distinct from and worse than her experience with ADHD. It is not psychosomatic, and involves real changes to the structure and chemistry of the brain. It is not a mood disorder: “If anyone is saying that this is due to depression and anxiety, they have no basis for that, and data suggest it might be the other direction,” Joanna Hellmuth, a neurologist at UC San Francisco, told me.
Robertson predicted that the pandemic would trigger a wave of cognitive impairment in March 2020. Her brain fog began two decades earlier, likely with a different viral illness, but she developed the same executive-function impairments that long-haulers experience, which then worsened when she got COVID last year. That specific constellation of problems also befalls many people living with HIV, epileptics after seizures, cancer patients experiencing so-called chemo brain, and people with several complex chronic illnesses such as fibromyalgia. It’s part of the diagnostic criteria for myalgic encephalomyelitis, also known as chronic fatigue syndrome, or ME/CFS—a condition that Davis and many other long-haulers now have. Brain fog existed well before COVID, affecting many people whose conditions were stigmatized, dismissed, or neglected. “For all of those years, people just treated it like it’s not worth researching,” Robertson told me. “So many of us were told, Oh, it’s just a bit of a depression.”
Michelle Monje, a neuro-oncologist at Stanford, told me. Instead, she thinks that in most cases the virus harms the brain without directly infecting it. She and her colleagues recently showed that when mice experience mild bouts of COVID, inflammatory chemicals can travel from the lungs to the brain, where they disrupt cells called microglia. Normally, microglia act as groundskeepers, supporting neurons by pruning unnecessary connections and cleaning unwanted debris. When inflamed, their efforts become overenthusiastic and destructive. In their presence, the hippocampus—a region crucial for memory—produces fewer fresh neurons, while many existing neurons lose their insulating coats, so electric signals now course along these cells more slowly.
Patients struggle to make peace with how much they’ve changed and the stigma associated with it, regardless of where they end up. Their desperation to return to normal can be dangerous, especially when combined with cultural norms around pressing on through challenges and post-exertional malaise—severe crashes in which all symptoms worsen after even minor physical or mental exertion. Many long-haulers try to push themselves back to work and instead “push themselves into a crash,” Robertson told me. When she tried to force her way to normalcy, she became mostly housebound for a year, needing full-time care. Even now, if she tries to concentrate in the middle of a bad day, “I end up with a physical reaction of exhaustion and pain, like I’ve run a marathon,” she said.
Post-exertional malaise is so common among long-haulers that “exercise as a treatment is inappropriate for people with long COVID,” Putrino said. Even brain-training games—which have questionable value but are often mentioned as potential treatments for brain fog—must be very carefully rationed because mental exertion is physical exertion. People with ME/CFS learned this lesson the hard way, and fought hard to get exercise therapy, once commonly prescribed for the condition, to be removed from official guidance in the U.S. and U.K. They’ve also learned the value of pacing—carefully sensing and managing their energy levels to avoid crashes.