One of the most troubling aspects of infection with the coronavirus appears to be that even among those who experience only “mild” cases (i.e., not requiring hospitalization), many appear to have lingering after-effects that impair their cognition, memory, and ability to focus their attention. In fact, among COVID patients over age 70, the infection appears to leave many with brain damage, due to an uncertain mix of systemic viral infection, inflammation, silent strokes, or lack of oxygen to the brain. We’re just in the beginning stages of understanding this neurologic impact of COVID. However, the phenomenon that many post-COVID patients, both younger and older, are experiencing is something akin to what has appeared in patients with other sorts of diseases and maladies, and is known by its non-medical term, “Brain Fog.” It’s a subjective experience of not being able to think clearly as your brain seems to slow down and have difficulty processing information. It can arise as a result of a disease but can also surface when a person is suffering from hormonal changes, stress, fatigue, anxiety, or lack of sleep- causes with which we may all be familiar.

People who are experiencing post-COVID brain fog seem to have a number of common symptoms, including a “haze-like” frame of mind with difficulty remembering, concentrating, and conversing. Some studies are suggesting that up to 20% of those diagnosed with COVID are left with this condition. With symptoms that also appear similar to those with PTSD or Chronic Fatigue Syndrome, some COVID patients even feel like they have dementia, given their memory loss, difficulty focusing, and inability to grasp even basic vocabulary words. As one such patient remarked in The New York Times, “Reading emails was like reading Greek,” due to the brain fog. What’s perhaps more worrisome is that the cognitive symptoms vary among patients and the brain problems seem to arise after the period of initial infection. So what’s going on? Experts are baffled and put forth a range of possibilities, from the fear and anxiety of becoming infected to a possible auto-immune response, or even to inflammation in the blood vessels leading to the brain. 

But these symptoms of “brain fog” are also common among other types of patients. Certainly, many patients undergoing chemotherapy experience a similar sort of confusion and difficulty concentrating, possibly attributable to such causes as the cancer itself, the therapies used to destroy cancer cells, or the complications from the cancer treatment. As well, those going through depression, which is often accompanied by sleep disruption or the introduction of new medications, can experience brain fog. Indeed, in older adults, it’s important to disentangle what may be “brain fog” as a result of brain slowing medications or other triggers versus what may in fact be the actual onset of dementia symptoms. 

Given the myriad of reasons that brain fog can set in, figuring out how to address it is a complicated affair. This is especially worrisome given that millions of people around the world who have survived COVID may be left with lingering cognitive symptoms that may seriously affect their day-to-day functioning. We do know that brain fog tends to ebb and flow and that there are compensatory strategies to buttress cognition and also address the symptoms, including better eating, sleeping, stress relief, and increased physical activity. Of course, it’s critical to work with your physician to determine whether your situation falls into the cloud of brain fog or whether something more concrete, and addressable, is going on. But the bottom line is that for many of us in this anxious and infectious time, determining the source of our mental haze and finding workable solutions appears to be an ongoing and uncertain process.