Cognitive dysfunction, often called “brain fog,” after recovering from COVID-19 infection has consistently come in second place to fatigue as the most common symptom of Long COVID. Multiple studies have now shown that the virus can affect the brain and nervous system. How, exactly, does COVID cause brain fog? Experts from Amen Clinics explain what we know so far, and what treatments may bring relief.*

About brain fog

Brain fog is an umbrella term that encompasses slower thought processing, confusion, forgetfulness, poor concentration, and lack of focus in people with conditions like Long COVID. 

Research has shown that SARS-CoV-2 virus follows the olfactory nerve (responsible for smell) after entering the nasal cavity. A large imaging study offers several clues as to why brain fog occurs. Comparing brain images before and after COVID infection, it was found that:

• Gray matter thickness decreased in areas involved in smell.
• Tissue damage occurred in the primary olfactory cortex, a brain region related to smell.
• Total brain volume declined.
• A certain part of the brain’s cerebellum, linked to cognition, decreased.

Another study found that people with Long COVID brain fog after mild COVID-19 had greater immune activity close to one year after infection. The results suggest that continual damage and repair of the brain’s blood vessels causes a hyperactive immune response, which leads to inflammation and then to brain fog. 

Amen Clinics’ own imaging of brains before and after COVID-19 showed elevated activity in the limbic system, which is involved in emotion and memory. Such activity has been linked to depression, which can also cause brain fog.

How is brain fog treated?

A couple of therapies are being used to address Long COVID brain fog, though their level of availability isn’t clear.

• Non-invasive microcurrent brain stimulation therapy was shown in research to improve cognition by 40% to 60% in one patient. In the study, alternating microcurrent stimulation was applied to the eyes and brain.
• Brain retraining through a particular kind of learning therapy makes use of neuroplasticity, or the idea that the brain is changeable and can expand its capacity. To rebuild memory, a person repeats information without error a predetermined number of times.

Amen says it’s important to take a holistic approach to treating brain fog, involving not just these therapies but also brain imaging, neuropsychological evaluation, lab work, and lifestyle.

Lifestyle support

Long COVID symptoms are closely tied to inflammation, so maintaining a lifestyle that helps lower inflammation may reduce brain fog and promote recovery. Experts suggest that you:

• Eat more prebiotic foods like apples, beans, unripe bananas, cabbage, and asparagus. These foods support healthy gut bacteria that reduce inflammation, while promoting a healthy gut-brain connection.
• Eat probiotic-rich foods (or take supplements), like sauerkraut, kefir, Kombucha tea, and pickled vegetables to support gut health and lower inflammation.
• Eat fatty fishes (or take supplements) containing omega-3 fatty acids, such as salmon, sardines, mackerel, and herring. Fish oil contains chemicals that support neuroplasticity and reduce overall inflammation.
• Avoid foods that cause inflammation, such as refined sugars, alcohol, refined flours, and processed meats.
• Remember to floss and brush daily. Gum health is essential to avoid inflammation.
• Make time for relaxation to reduce stress that can cause inflammation.
• Engage in moderate daily exercise, which is “excellent for the brain.”

As we learn more about brain fog, Amen says any of these steps can help support brain health and cognition right now.

*Amen Clinics. (2022, June 6). Struggling with COVID Brain Fog? 7 Ways to Clear Your Head. https://www.amenclinics.com/blog/struggling-with-covid-brain-fog-7-ways-to-clear-your-head