People struggling with “long Covid,” or the persistence of symptoms after an initial Covid-19 infection, can face cognitive difficulties such as “brain fog” and memory problems. Now, a study finds the severity of these symptoms is comparable to the brain aging ten years.
By testing the mental speed and accuracy of participants who had and had not been diagnosed with Covid-19, researchers found the cognitive decline was worst for people who had experienced Covid symptoms for more than 12 weeks, according to a study published this month in eClinicalMedicine, a journal published by The Lancet.
“The fact remains that two years on from their first infection, some people don’t feel fully recovered, and their lives continue to be impacted by the long-term effects of the coronavirus,” Claire Steves, a co-author of the study who researches aging and mental health at King’s College London, says in a statement.
In 2020, a separate team of researchers examined the brains of people who had died from Covid-19 and discovered their blood vessels, which were covered with antibodies, had sustained significant damage, reports Time’s Jamie Ducharme. The scientists concluded the virus had somehow caused the body’s immune system to attack its blood vessels, leading to inflammation in the brain.
It’s not clear whether this inflammation is the cause of brain fog and cognitive difficulties in living patients with long Covid, but Lara Jehi, a researcher at the Cleveland Clinic who was not involved in the current study or the 2020 research, tells Time she’s seen it impact both people with long Covid and Alzheimer’s disease. “We found many areas of overlap between the two, and these areas of overlap centered on…inflammation in the brain and microscopic injuries to the blood vessels,” she tells the publication.
To better understand long Covid’s effect on the brain, the new study put more than 3,000 participants through 12 different types of cognitive tests designed to measure memory, processing speed, attention, motor control and other thinking skills. A little over half of the participants had previously tested positive for Covid-19, and all were recruited through the Covid Symptom Study Biobank smartphone app.
In the first round of testing in 2021, researchers found the cognitive impairment associated with long Covid was clear, comparable to the brain being under “mild or moderate symptoms of psychological distress,” or ten years of aging, write the authors in the paper. During the second round of testing, which took place in 2022, patients showed no significant improvement. At that point, some participants’ cognitive decline had lasted nearly two years after infection.
The positive takeaway? Once a person’s Covid symptoms disappeared—regardless of whether they had persisted for three months or one week—their cognitive function appeared to recover.
This, at least, is “good news,” says Nathan Cheetham, a senior postdoctoral data scientist at King’s College London and study co-author, in the statement.
“This study shows the need to monitor those people whose brain function is most affected by Covid-19, to see how their cognitive symptoms continue to develop and provide support toward recovery,” he says in the statement.
About 15 percent of U.S. adults have experienced long Covid, according to the Household Pulse Survey by the National Center for Health Statistics. In the United Kingdom, about two million adults were impacted by the persistent condition as of January 2023, reports the Guardian’s Geneva Abdul.
Steves calls for more research into how long Covid victims can be aided in their recovery process, especially those who have been living with the symptoms for years.
“We need more work to understand why this is the case and what can be done to help,” she says in the statement.