If you suffer from chronic sinusitis — a condition that affects more than 10 percent of the U.S. population — a stuffy nose and postnasal drip may be the least of your worries. Research has uncovered a link between chronic sinusitis and cognitive deficits — or, as most people who have this problem call it, “brain fog.”
What Is Brain Fog?
Brain fog is not a clinical term but a colloquial one, explains Aria Jafari, a surgeon and an assistant professor in the Department of Otolaryngology–Head and Neck Surgery at the University of Washington School of Medicine.
People describe the experience as the inability to concentrate, making it difficult to take care of everyday tasks — for example, forgetting what was on your grocery list or having difficulty following directions to a place you’ve not been before, explains Jafari.
Analyzing Chronic Sinusitis and Brain Fog
Most of the research on sinusitis and cognitive deficits has been based on patients’ reports of feeling less than on top of their mental game. But Jafari wanted to be able to characterize in a more objective way what these people are experiencing.
So, he and colleagues gave 24 volunteers who suffer from chronic sinusitis a battery of cognitive tests, including the Montreal Cognitive Assessment (MoCA) and the Neuro-OOL Cognitive Function tests. They also tested the participants with software that tracked their eye movements while they performed onscreen tasks, a common way of assessing cognitive ability. Participants also filled out the delightfully named SNOT-22 (Sino-Nasal Outcome Test-22) quality of life questionnaire.
The results of these tests were compared with the results of the same tests from 23 healthy controls — people who did not have sinusitis. Indeed, patients with chronic sinusitis reported more cognitive dysfunction on the questionnaire and showed at least some impairment on the tests as compared with the healthy controls. In fact, some measure of cognitive dysfunction was found in almost half of the sinusitis patients. The team’s research was published in January 2024 in the journal International Forum of Allergy and Rhinology.
Chronic Inflammation Could Cause Brain Fog
Why chronic sinusitis causes brain fog isn’t entirely clear, and understanding the connection is the point of Jafari’s research. For example, he was the lead author of a 2021 study that used functional magnetic resonance imaging (fMRI) to identify subtle changes in brain function that might result from the inflammation of sinusitis.
The study found decreased connectivity in the frontoparietal cortex, what Jafari describes as the “central hub” or “gatekeeper” of a lot of neural signaling. “Interestingly,” he says, “that network sits really close to the interface between the brain and the sinus.”
However, he doesn’t yet know if the disruption in signaling is due to inflammatory disruption — meaning the signaling is disrupted by molecules coming from the nose to the brain — or if it’s more the kind of effect you’ll likely recognize if you’ve had the flu or COVID-19 and found that your thinking is slow and muddled.
Still, Jafari suspects that the problem is a result of a massive inflammatory reaction in the body that crosses the blood-brain barrier.
“We previously thought of the blood-brain barrier as a very tight barrier between the body and the brain. More recently, we’ve realized that it’s probably more permeable than we thought and likely influenced by some inflammatory mediators or inflammatory actors that can subtly change the way we think and behave,” says Jafari.
Whatever the cause turns out to be, this latest research does validate the reported experience of people who have chronic sinusitis and brain fog. But sinusitis sufferers still want to know: Will treating sinusitis take care of the cognitive issues? Stay tuned. That’s the next phase of the research, says Jafari.
“Knowing if this is reversible, and how quickly it's reversible and in what way would be hugely helpful as we treat these patients holistically,” he says.