Lost in a Brain Fog

Photo illustration of woman with fog surrounding head

If you find yourself unable to focus, struggling to remember daily tasks or feeling extreme mental fatigue, you’re not alone.

While COVID-19, especially the long form of the disease, has caused a noticeable uptick in cognitive dysfunctions, “brain fog” was a problem long before the pandemic struck — and numerous other culprits can cause it. 

Emory researchers clear up some of the mysteries behind this debilitating condition and offer up some practical strategies to cope with it. 

More than 22% of people infected with COVID-19 report brain fog as a symptom. Sufferers say their brains feel “broken,” causing problems with focus, memory and energy levels, and sometimes even outright physical pain.

However, COVID-19 is just one of many illnesses and conditions — from menopause to migraines, Lyme disease to chemotherapy — that cause it. We asked Emory medical experts to help us better understand brain fog’s various causes and manifestations, as well as to share some advice for people who find themselves mired in its stuporous vapor.

Illustration of fog hovering over outstretched hand


While most people recover from mild COVID-19 symptoms over the course of one to two weeks, long COVID patients can suffer from lingering symptoms, including cognitive complaints and brain fog, for months or even years. Nearly one out of every five adults who have had COVID develop long COVID, defined as symptoms lasting three months or more, according to the Centers for Disease Control and Prevention’s National Center for Health Statistics.

Alex Truong, Emory assistant professor of pulmonology, works with patients at Emory’s Executive Park post-COVID clinic. “A lot of our patients come in with very, very similar symptoms of brain fog, fatigue and shortness of breath,” says Truong. “It’s very rare that someone comes in with a singular issue. It’s always a host of issues. Most of the time, patients are complaining that their brain fog and fatigue are the biggest limiters of their activities of daily living — their ability to get back to work, the ability to go back to school or take care of their kids.”

Some patients experience severe enough cognitive difficulties and fatigue that they have had to quit work or go on a leave of absence. But long COVID and brain fog are still sometimes met with skepticism and impatience, whether by doctors, employers, friends or family.

“I worry that a lot of the symptoms are subjective: brain fog, shortness of breath, fatigue,” says Zanthia Wiley, Emory associate professor of infectious diseases. “When there are no lab tests to confirm it, some patients are less likely to be believed. Research will provide some of these answers through better testing mechanisms and treatments, so we will have more to offer people.”

Multiple studies are being conducted on postacute sequelae, the medical term for lingering symptoms of a SARS-CoV-2 infection. The patient interviews have resulted in vivid descriptions of brain fog. Subjects say they have “muddled or fuzzy thoughts,” that their brain feels like it has “a bad wi-fi connection to a router,” that their thoughts are “in slow motion” or disappear like “smoke” or a “dream.”

Brain fog, they say, has impacted their abilities to work at their job, do household chores, recall facts, read, write, focus, multitask, drive safely or even put together a coherent sentence. And the symptoms and their severity often get worse as the day goes on.

“Brain fog is one of the primary symptoms of long COVID, often persists and can be quite debilitating for some,” says Tiffany Walker, assistant professor of medicine at Emory, who practices internal medicine at Grady Hospital in Atlanta.edicine at Emory who practices internal medicine at Grady Hospital in Atlanta.

Walker co-founded the Grady post-COVID clinic and co-established a multisite long COVID registry and biorepository. She is also current co-principal investigator of an Emory subsite for the RECOVER (Researching COVID to Enhance Recovery) initiative of the National Institutes of Health.

“Unfortunately, we have found that even some COVID-19 survivors that do not notice symptoms of brain fog actually have evidence of cognitive impairment on comprehensive neurocognitive testing,” she says. “There are high rates of depression and anxiety in long COVID, and these illnesses can lead to brain fog as well, but it is important to note that brain fog certainly occurs independent of mood disorders and should not be entirely attributed when they exist concurrently.”

Walker says there is concern that COVID-19 can result in neurodegeneration, which is currently under investigation. “There are no FDA-approved treatments for long COVID–related brain fog,” she says, “but current strategies target guidance on techniques to compensate and cognitive pacing by avoiding overburdening cognitive loads.”


One of the first mentions of brain fog was in 1850 by British physician James Tunstall. He described it as a type of mental exhaustion experienced by lawyers, writers, teachers, students and other “brainworkers” as a consequence of “overworking [the] mental facilities without sufficient bodily fatigue.”

This early precursor to what we now identify as brain fog was included in the DSM-IV (Diagnostic and Statistical Manual of Mental Disorders, 4th Edition) as a “culture-bound” syndrome associated with excessive academic strain.

Prior to the COVID-19 pandemic, brain fog was most often associated with chronic fatigue syndrome and fibromyalgia (known as “fibro fog”).

Chronic fatigue is a debilitating and complex disorder characterized by intense fatigue that is not improved by bed rest and that may be worsened by exercise or mental stress. Patients describe not only persistent and overwhelming physical fatigue but mental fatigue as well, characterized by slow thinking, difficulty focusing, confusion, forgetfulness or “haziness” in their thought process.

A brain-imaging study conducted at Emory by psychiatrist Andrew Miller in 2014 showed that patients with chronic fatigue syndrome may have reduced responses, compared with healthy controls, in a region of the brain connected with fatigue. Patients with chronic fatigue syndrome had less activation of the basal ganglia, as measured by fMRI (functional magnetic resonance imaging).

“We chose the basal ganglia because they are primary targets of inflammation in the brain,” said Miller, William Timmie Professor of Psychiatry and Behavioral Sciences at Emory and lead author of the study. “Results from a number of previous studies suggest that increased inflammation may be a contributing factor to fatigue in chronic fatigue syndrome patients and may even be the cause in some patients.”

His team’s more recent data also suggests that these inflammation-related changes in the basal ganglia may be related to a depletion in dopamine, which can be reversed by the administration of drugs that increase dopamine’s actions in the brain or the blockade of inflammation.

“These exciting findings may provide new approaches to treating fatigue and brain changes in the future,” Miller says.


From chemotherapy to menopause to insomnia, a sizable host of other illnesses, conditions and even medications can cause brain fog.

Chemotherapy can result in what has been called “mental fog” or “chemo brain,” which is usually short-term but can also last for months or years after treatment.

“Chemotherapy does not only kill cancer cells but can have systemic effects throughout the body, including healthy cells within the brain,” says neuro-oncologist Madison Shoaf of Emory’s Winship Cancer Institute. “When particular regions of the brain are affected, people can experience various cognitive challenges, such as difficulty with focus, multitasking, and short-term memory.”

These symptoms can be exacerbated by other factors like poor sleep, fatigue and mood changes that may be experienced during cancer treatments. “The duration of symptoms can vary from person to person, but for those with persistent symptoms, neurocognitive rehabilitation may be helpful,” she says.

Depression, anxiety, stress, drugs (legal or illegal) or alcohol, insomnia, aging, jet lag, Lyme disease, antihistamines, lupus, hormonal changes during pregnancy, too much screen time … all have been associated with brain fog.

One of the most common is menopause.

“Many women complain of brain fog during menopause, which is actually worse during the perimenopausal transition than after menopause has occurred,” says Mary Dolan, Emory professor of obstetrics and gynecology. “It can be difficult to tease out — is there brain fog because they are not sleeping well (due to disrupted sleep from hot flashes) or mood changes, which can be hormonal? Or are there brain-processing changes due to hormonal fluctuations or aging?”

A bit of good news has emerged, says Dolan, a certified menopause practitioner: “Some data imply that even though there is a trend for memory to be worse during the menopause transition, memory after the transition may be as good as it was before.”

Sleep disturbances in and of themselves can cause brain fog. Some of the factors that cause sleepless nights or disrupted sleep are more common in midlife, such as sleep apnea (sometimes related to obesity), restless leg syndrome, stress, anxiety, depression, becoming caregivers for aging parents and some medications.


“While brain fog has become a term commonly used since COVID-19, it refers to a constellation of cognitive and emotional symptoms such as poor concentration and memory that were common prior to COVID-19 and remain prevalent as a result of common lifestyle factors,” says Sharon Bergquist, Pam R. Rollins Professor of Medicine and director of Emory Lifestyle Medicine and Wellness. “For example, stress, lack of sleep, inadequate exercise, poor diet, prolonged sedentary time and many other factors can all contribute to lack of mental clarity. While COVID-19 can cause neuroinflammation, for many people the symptoms of brain fog may not be related to COVID-19.”

In general, Bergquist says, “It’s more helpful to address the factors that are within your control. Many of our patients experience improvement by adopting habit changes. There is a lot of scientific literature supporting the benefits of exercise, social engagement, learning new tasks. A Mediterranean dietary pattern has been shown to improve cognitive function. And there is emerging support for the benefits of intermittent fasting.”

Lifestyle improvements not only may help reduce brain fog, they also reduce the risk of Alzheimer’s and dementia. “The bottom line,” she says, “is that we can all benefit from putting effort into strategies that optimize brain health.”

Design by Laura Dengler. Photos by Getty Images.


Given that brain fog can be caused by a host of different ailments, advice varies on how to address it and no magic pill exists. But techniques have emerged that have been proven to help across the board. Emory’s Mary Dolan and Sharon Bergquist offer these lifestyle tips for reducing brain fog and improving general health.


Especially if you are suffering from a concurrent condition like COVID, cancer or a difficult pregnancy, take it easy and don’t push yourself. Get plenty of rest.


Maintain an extensive social network. Consume a healthy diet. Don’t smoke. Alcohol in any amount can make brain fog worse. Drink fluids, especially water.


A brisk 10-minute walk to break up sedentary time improves vigilance and cognitive performance.


Talk to a friend or counselor. Meditate. Exercise. Identify and reduce your stress triggers.


Atherosclerosis (hardening of the arteries) may contribute to mental decline, so aim for normal cholesterol, weight and blood pressure to help protect your brain. 


Use regular hours to sleep each night. Don’t get too warm while sleeping. Avoid caffeine. Limit screen time right before sleep. If lifestyle changes don’t help, see a sleep specialist.


Resisting the constant urge to check emails and texts improves concentration and ability to work through complex tasks. 


When dividing time between work obligations and caring for family, remember that taking care of your own needs is equally important.

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