Photo by Edward Jenner.

Also known as “clouding of consciousness” (but who can remember that if you have it?) brain fog is a collection of symptoms that can occur during a wide variety of conditions including long covid, fibromyalgia, chronic fatigue syndrome, and lupus. It has also been reported by patients undergoing chemotherapy, and is associated with mental health issues from depression to schizophrenia.

What is brain fog, anyway?

Medical science has been trying to pin down an exact definition of brain fog for a long time, as it is a constellation of symptoms that can have a wide range of causes. First mentioned in 1850, British physician James Tunstall attributed the symptoms to extreme mental exhaustion experienced by overworked lawyers, teachers, writers, and students. Modern life seems to have made the symptoms less confined to those who overuse their gray matter, and an improved understanding of the human brain has enabled medical science to accept that the debilitating symptoms described by patients are common to diverse conditions.

Some 20-30% of former Covid-19 patients experience regular brain fog, especially among those in their 20’s, 30’s, and 40’s. Many millions more experience it through other causes. 

A symptom with many sources

Patients report rather similar symptoms: difficulty concentrating, confusion, forgetfulness, fatigue, and cognitive slowness.

Long covid has turned the spotlight on brain fog as scientists are still trying to figure how and why long covid occurs. Before the Covid-19 pandemic, brain fog was experienced not just by sufferers of chronic fatigue and fibromyalgia, but also during perimenopause and as a result of stress. Other contributing conditions include Parkinson’s disease, stroke, and multiple sclerosis. Prescribed drugs, as well as recreational drugs, can cause brain fog, as can jet lag, insomnia, low levels of serotonin (a neurotransmitter that regulates mood, memory, and gut balance) in the brain, and hormonal changes.

Whatever the trigger, patients report rather similar symptoms: difficulty concentrating, confusion, forgetfulness, fatigue, and cognitive slowness. Because certain kinds of cognitive impairment can be measured and the cause can be found, such as when an area of the brain has been injured or has a disease, patients who report brain fog are often left frustrated by a diagnostic process that falls short of connecting the dots when the cause of their symptoms cannot be detected.

The nebulousness of the symptoms’ origin has caused some physicians to believe that brain fog is purely psychological, or “all in your head.” For better or worse, the research into long covid has begun to challenge that dismissive stance.

Inflammation: a common thread

Brain researchers now understand that some of the symptoms caused by brain fog are related to the brain’s executive function center, located in the frontal lobes. Many of us know how hard it can be to think clearly when we’re exhausted, sick, or overwhelmed, i.e. stressed out. These scenarios, as well as many of the other conditions associated with brain fog, have been shown to have at least one feature in common: inflammation. At least in the case of long-covid sufferers, an overactive or inaccurately directed immune response may cause neuroinflammation when the immune system attacks healthy brain cells, sometimes even resulting in long-term decreased size of white or gray matter.

Similar patterns of inflammation have been detected in chronic fatigue syndrome and chemotherapy patients.

Another line of inquiry is into defects in the blood-brain barrier, a membrane that normally protects the brain from harmful molecules such as toxins and viruses. A leaky blood-brain barrier has been found in lupus and chronic fatigue patients.

Declining estrogen levels in menopausal women have been linked to shrinkage of some brain areas, as has hypothyroidism, leading to cognitive haziness. 

Even chronic pain can cause brain fog as it wears on the nervous system.

The recent understanding of the gut biome’s integral connection to the brain has led to speculation that an imbalance of microbes in the gut can lead to brain fog.

Even chronic pain, experienced by up to 51 million Americans, can cause brain fog as it wears on the nervous system.

With these many and varied conditions present in the health histories of those who experience debilitating brain fog, there is a growing opinion among scientists studying the matter that it will be best to treat brain fog by identifying the specific cause whenever possible and treating that root cause.

One therapeutic approach has been helpful for patients whose brain fog persists whether or not a root cause can be identified. Cognitive Behavioral Therapy involves a number of talk therapy sessions with a provider trained to help you identify habitual patterns of thought and behavior, and through that enhanced awareness you become able to modify the negative patterns, lifting the fog.

Medications such as those used for ADHD and others used for immune diseases such as lupus are also showing some benefit to those who suffer from brain fog.

What you can do right now

If your brain fog is occasional, think about lifestyle factors that may be triggering it such as poor sleep, poor diet, or stress. Perhaps a new medication has been introduced, a traumatic event has overwhelmed you, or you are working too hard. If your brain fog persists for more than a few weeks, it’s probably time to see your medical provider for a deeper dive into the possible cause. Make sure to find a provider who validates your concerns and understands that your symptoms are real.

Ann Constantino, submitted on behalf of the SoHum Health’s Outreach department.