A new study links long COVID to a threefold increase in cognitive difficulties, highlighting the need for more research on the disease’s impacts on brain health.
Long COVID, a baffling constellation of physical symptoms that may persist long after a bout of COVID-19, can strike almost every system in the body. Perhaps unsurprisingly then, new evidence links the condition to an increased risk of problems with memory and thinking. A recent study published in the journal Biology Methods and Protocol found that people with long COVID were three times more likely to experience cognitive deficits than those who never had the virus.
While it’s not a smoking gun, the study adds to growing evidence that long COVID can affect brain health in important ways, explained Nianjun Liu, professor of public health at Indiana University Bloomington and co-author of the study. Those include mental sluggishness, difficulty concentrating and remembering, as well as an array of problems that include headaches, seizure disorders, strokes, sleep problems, and tingling and paralysis of the nerves, as well as several mental health disorders.
In this most recent study, Liu said the research “shows some interesting associations [with long COVID] that can give us clues about what may be happening cognitively.”
Liu and co-author Daniel J. Wu analyzed census data reported by more than 385,000 adults in 2022, homing in on questions pertaining to cognitive difficulties. They also considered sociodemographic variables like age, gender, race/ethnicity, education, and area of residence, all of which can influence cognitive health and long COVID.
When compared with similar data collected before the pandemic, researchers found that respondents showed nearly triple the odds of having a cognitive deficit.
The data, meanwhile, also produced other surprising results.
“We found the effects of long COVID were most significant in older people and individuals with higher education,” Liu said. And yet when evaluating the same demographic of people who were not affected by the disease, fewer cognitive deficits were reported.
He then shared his thoughts on the findings.
“People with higher education [were] more sensitive to small changes in their thinking and memory. And maybe uninfected elderly people [were] less sensitive to (those changes) or have anosognosia” (a condition in which someone doesn’t recognize their own mental health or neurological conditions). “But,” he added, those people could also be “more vulnerable to the cognitive effects of long COVID.”
The analysis was unclear, even though the demographic data showed some differences.
For example, while men and women were equally at risk for cognitive deficits after long COVID, Hispanics had a lower risk than other ethnic/racial groups. There were also regional differences. In Kentucky and West Virginia, for instance, about 20 percent of people with long COVID reported cognitive deficits. The lowest rates were in Connecticut (11.6 percent) and Hawaii (12.3 percent).
Exploring more links between COVID and cognitive health
Building on the link between long COVID and cognitive deficits, a separate study explored how COVID-19 affects brain health through changes in biochemical markers and brain structure.
In January, a group of U.K. researchers reported altered levels of Alzheimer’s biomarkers in the blood plasma of people who had experienced a COVID-19 infection. These include decreased beta-amyloid 42 (the main component of the beta-amyloid plaques that build up in the brains of people with Alzheimer’s). This, according to researchers, might suggest that more beta-amyloid is accumulating in the brain, leaving less in circulation in the rest of the body. They also found increased levels of other “red flag” proteins: p-tau and neurofilament light, both of which are associated with neuronal damage. Finally, there was an increase in a protein called glial fibrillary acidic protein — a marker of brain inflammation.
Several previous imaging studies also found post-COVID structural changes in brain regions important in memory and thinking. In fall of 2024, for example, a team at Mount Sinai in New York analyzed the brains of a group of young Italians who had mild to moderate cases of COVID-19. They saw decreased volume in the hippocampus — the seat of long-term memory — and fewer connections between the amygdala and other regions in the brains.
Dr. Heather Snyder, a Alzheimer’s Association senior vice president of medical and scientific relations, said when you look over the landscape of all this data on long COVID and Alzheimer’s, the results are certainly intriguing — but they don’t mean long COVID causes Alzheimer’s or other cognitive disorders.
“It’s really unclear why one group might be experiencing these changes, and another group might not,” she told Being Patient. “Is it driven by genetics? By some other factor? Research that uses self-report is certainly important,” but it isn’t able to identify causal relationships – but rather merely associations. “When you look at this as part of the larger area of study that’s unfolding, it does beg a lot of questions that we need to explore and understand.”
