Post-COVID ‘brain fog’ might be caused by changes in spinal fluid, new study suggests

(Gray News) - Long COVID-19 can cause many lingering symptoms for months, including “brain fog” – problems with thinking, memory, and concentration. A recent small study from the University of California San Francisco might provide a clue as to why this happens, and it has to do with abnormalities in patients’ cerebrospinal fluid.

The study looked at 32 adults, including 22 with brain fog and 10 control participants without brain fog. Seventeen of the patients underwent a lumbar puncture to observe their spinal fluid. All 17 participants had had COVID-19 but had not required hospitalization.

The lumbar punctures took place on average 10 months after the person’s first COVID-19 symptom.

Researchers found that 10 out of 13 patients with brain fog had anomalies in their spinal fluid – yet all four of the spinal fluid samples from people without brain fog showed up as normal.

The anomalies found in patients with brain fog included elevated levels of protein, suggesting inflammation, and the presence of unexpected antibodies usually found in an activated immune system. Some patients had these antibodies found in both their spinal fluid and in their blood, suggestion a systemic inflammatory response, but others only had the antibodies in their spinal fluid, suggesting brain inflammation.

Researchers also discovered that people with preexisting health conditions had a higher chance of having brain fog, compared to those without prior health issues. On average, those with brain fog had an average of 2.5 cognitive risk factors, such as diabetes and high blood pressure, and those without brain fog had an average of less than one risk factor.

In another study published this month, researchers found that brain fog is a common symptom of long COVID, affecting 67% of 156 patients studied at a post-COVID clinic in New York.

Brain fog and cognitive symptoms have been found with other viral infections, including SARS, MERS, hepatitis C, and Epstein-Barr virus.

The University of California San Francisco study was published Jan. 18 in Annals of Clinical and Translational Neurology.

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