The phrase “brain fog” has exploded in our collective lexicon in recent years, along with complaints and concerns about “senior moments,” forgotten names, lost items, an inability to focus and clouded thinking.
To add to our common distress, a recent Bloomberg News explainer highlighted several studies showing that COVID-19 damaged our brains by shrinking their volume, diminishing our cognitive performance, and increasing the presence of protein deposits associated with Alzheimer’s disease.
So, how worried should we be? A minority of those infected with the virus indeed developed what has become known as long COVID.
Illustration: Mountain Peopl
Doctors say brain fog is the most common symptom of the syndrome, which can also include fatigue, insomnia, tinnitus and balance problems. Could the rest of us “COVID survivors” — now the vast majority of the population — suffer from some milder form of the disorder? It is a scary thought made worse by the studies suggesting that COVID carries a higher dementia risk.
However, so much has happened since COVID-19 swept through the population. Technology has changed the demands of our work and personal lives, stress has taken a toll on some of us and we are aging. There might be other, less alarming explanations for brain fog than some indelible damage from this particular virus.
In New York magazine, a writer recently described her battle with brain fog, which she says predated her having COVID. It caused her to forget names and Zoom meetings.
However, before the pandemic, most of us did not have to juggle Zooms — we met in person. Meetings were harder to forget when we could see our office mates getting up from their cubicles and heading to a conference room. Juggling our work lives on our phones makes lapses even more likely.
The most compelling studies pointing to some COVID-related impairment rely on brain data collected before the pandemic, which allowed scientists to make direct comparisons of the same people before and after infection. One such study showed that, on average, people who had had even mild COVID-19 showed a slight change in tests of cognitive abilities and subtle changes in their brain scans.
That sounds terrible, but the changes were small and might not affect people’s lives, said the study’s lead author, Johanna Daily of Albert Einstein College of Medicine and Montefiore Medical Center in New York.
“I think we’ll be okay,” she said, referring to most of the population.
Scientists in the UK were able to use much larger data sets collected from brains pre-pandemic through a project called the UK Biobank. By bringing some of the same participants back and retesting them post-infection, they could compare cognitive tests, brain scans and blood markers for dementia risk.
Paul Matthews, a neurologist and leader of the UK Dementia Research Institute at Imperial College London, said that people who had had COVID-19 were more likely to show very small changes in certain substances in the blood that correlate with dementia risk.
Those include the proteins beta-amyloid and tau — both of which play a role in the development of Alzheimer’s.
Matthews said the research community has renewed interest in the idea that other viruses might be an underlying cause of Alzheimer’s disease. The amyloid and tau proteins previously thought to cause the disease might play an intermediate role, collecting in the brain due to the immune system reacting to viral threats.
The blood markers that indicate the level of these proteins in the brain tend to increase with age. Matthews estimated that, on average, the changes associated with COVID-19 amounted to about four years’ worth of aging. Would that lead to an increase in the rate of dementia down the road?
“I will watch that with some interest, but on balance, I don’t think it’s highly likely,” he said.
If the average result was four years of aging, some might have suffered less than that.
The fact that changes were measurable might scare people, but the changes were minor. Getting COVID-19 might be no worse for the brain than getting the flu. We have never had so much data on the effects of any infectious agent on the brain before — making it easy to think there is something uniquely damaging about mild COVID.
Scientists also measured cognitive changes in volunteers who entered a human challenge study in which people were deliberately infected with COVID-19. The changes, on average, were measurable, but too small for the subjects themselves to notice.
Matthews said those studies were done before the Omicron variant of the virus appeared and before most of the population was vaccinated, so we do not know if later infections had the same effect.
Meanwhile, all of our brains have aged five actual years since 2020. Some women went through menopause, which can also cause temporary sleep disturbances and brain fog. Our brains are getting older, yet we constantly expect more of them.
It is normal to have the occasional senior moment, said Karen Dahlman, an assistant professor of psychiatry at Icahn School of Medicine at Mount Sinai. That can mean forgetting names, losing things, or leaving a briefcase in a taxi. She said she and her husband half-joke about lapses as the “BOE” for the beginning of the end.
It is normal to forget where you put your keys; it is not normal to pick up your keys and forget what they are used for, she said.
Brain fog has always been here; now it just has a catchy name. While past COVID-19 infections might play a role, our phones and laptops also sap our attention, which can lead to — now I remember — mental exhaustion.
F.D. Flam is a Bloomberg Opinion columnist covering science. She is host of the Follow the Science podcast. This column does not necessarily reflect the opinion of the editorial board or Bloomberg LP and its owners.
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