November 28, 2022 – In early September, about a week after recovering from COVID-19, Barri Sanders went to the bank to pay a bill. However, she accidentally transferred a large amount of money from the wrong account.
“I’m talking about $20,000,” she says. “I had to go back [later] and fix it.”
Sanders, 83, had never had such confusion. Suddenly, the Albuquerque, NM resident realized that she looked up from a book and didn’t remember what she had just read. She got up from her chair and forgot what she was doing.
“I kind of thought it was just the aging process,” she says. Combined with sudden loss of balance, insomnia, and a nagging postnasal drip, the overall effect was “subtle but frightening,” she says.
After 5 days she went to bed and slept through the night. She woke up in the morning to find her balance restored, her sinuses clear and the mental fog gone. What she had, she realized, was not a sudden onset of dementia, but a mercifully brief form of long-term COVID.
Between 22% and 32% of people who recover from COVID-19 get “brain fog,” a nonscientific term used to describe slow or sluggish thinking. While this is troubling at any age, it can be particularly upsetting for older patients and their caregivers who fear they are not just having or witnessing an after-effect of an illness, but the beginning of a permanent loss of thinking ability. And some scientists are beginning to confirm what doctors, patients and their families can already see: Elderly patients who have had COVID-19 are at greater risk of developing dementia, or, if they already have mental confusion, the disease may worsen their condition.
British scientists studying medical records from around the world reported in the journal The Lancet Psychiatry in August that people who recovered from COVID-19 were at higher risk of thinking problems and dementia even after 2 years.
Another 2022 study published in the journal JAMA Neurology, studied elderly COVID-19 patients for a year after they were discharged from hospitals in Wuhan, China. Compared to uninfected people, those who survived a severe case of COVID-19 had a higher risk of early onset, late onset, and progressive decline in their ability to think. The study found that those who survived mild infection were at greater risk of early decline.
Eran Metzger, MD, an assistant professor of psychiatry at Beth Israel Deaconess Medical Center in Boston, says he’s noticed that COVID-19 is confusing some elderly patients and their brains aren’t regaining their former clarity.
“We see a gradual decline in their cognition during the COVID episode, and then they never go back to baseline,” says Metzger, medical director at Hebrew SeniorLife.
New research is beginning to support such findings.
People who contracted COVID-19 were twice as likely to be diagnosed with Alzheimer’s disease in the 12 months after infection compared to those who didn’t contract COVID, according to a study published in the journal Nature in September, which analyzed the US Department of Veterans Affairs health databases.
Joshua Cahan, MD, a cognitive neurologist at Northwestern University, advises caution in applying such a specific label simply from a patient’s medical record. After all, few patients would be tested to confirm they had the Alzheimer’s-related proteins.
“Probably the most relevant conclusion from this is that there is an increased risk of dementia after COVID infection,” he says, “but we don’t know whether it really is Alzheimer’s disease or not.”
There could be a number of reasons why COVID-19 is triggering a decline in thinking ability, says Michelle Monje, MD, a neuroscientist and neuro-oncologist at Stanford University.
In an article published in the magazine in October cellMonje and her co-author Akiko Iwasaki, PhD, Professor of Immunobiology at Yale University, propose six possible triggers for the brain fog caused by COVID: inflammation in the lungs and airways leading to inflammation and dysregulation of the central nervous system; autoimmune reactions that damage the central nervous system; brain infection directly caused by the coronavirus (although this appears rare); reactivation of an Epstein-Barr virus, which can lead to neuroinflammation; triggered by the corona virus; and/or complications from severe cases of COVID-19, possibly with periods of low blood oxygen and multi-organ failure.
Scientific understanding of brain fog is “part of an emerging picture that inflammation can be transmitted elsewhere in the body to become inflammation in the brain,” says Monje. “And once there’s inflammation in the brain … that can dysregulate other cell types that normally support healthy cognitive function.”
One problem with the concept of brain fog is that the condition, like the term itself, is difficult to define for doctors and patients alike and difficult, if not impossible, to capture on standard cognitive tests.
Today, patients often come to the Center of Excellence for Alzheimer’s Disease in Syracuse, NY, and complain that they “don’t feel the way they did before they contracted COVID-19,” says Sharon Brangman, MD, director of the center and the chair of the Department of Geriatrics at Upstate Medical University.
But the evidence for decreased cognition just isn’t there.
“We can’t objectively find anything wrong with them,” she says. “You’re not strong enough to do poorly on mental status tests.”
But specialized, targeted testing can find some likely signs, says Cahan, who assesses patient cognition at a long-running COVID clinic at Northwestern University.
He often finds that his long COVID patients score in the low normal range on cognitive tests.
“Patients have a complaint that something has changed and we don’t have previous testing,” he says. “So it’s possible that maybe they were in the high normal range or in the superior range, but you just don’t know.”
He says he’s seen very high-performing people like lawyers, executives, graduate students and other professionals who have tests that could be interpreted as normal, but given their level of performance “one would expect [higher scores].”
Like Sanders, many of those confused after contracting COVID are reverting to their former mental states. A study published in the journal brain communication Last January, it was found that people who had recovered from COVID-19, even if they had mild illness, were significantly more likely to have memory and other cognitive problems in the months following infection. But after 9 months, the former COVID patients had returned to their normal level of cognition, the team from Britain’s Oxford University reported.
However, it is noteworthy that the average age of the study participants was 28.6 years.
At Northwest Clinic, Cahan treats patients who have been struggling with COVID-induced cognitive problems for months or even years. A rehabilitation program involves working with patients to find ways to compensate for cognitive deficits — like making lists — as well as brain exercises, Cahan says. Over time, patients can see an improvement of 75% to 85%, he says.
Monje hopes that one day science will find ways to completely reverse the decline.
“I think what’s probably the most common contributor to brain fog is this neuroinflammation that causes other cell types to malfunction,” she says. “And at least in the lab we can salvage that in mouse models of the chemotherapy brain fog, which gives me hope that we can salvage that for humans.”