COVID can affect cerebrospinal fluid, causing ‘brain fog’, study finds

January 21, 2022 — A small study may help explain the cause of “brain fog” the persistent mental confusion reported in some people who have had COVID.

Researchers at the University of California, San Francisco found abnormalities in the cerebrospinal fluid – the clear, colorless fluid found in the brain and spinal cord – of 10 of 13 people infected with COVID and with thinking problems. Four fluid samples from people with COVID who did not have reflective issues showed no abnormalities.

According to the study published in the Annals of Clinical and Translational Neurology. All participants underwent a series of in-person cognitive tests and were scored according to criteria for HIV-Associated Neurocognitive Disorder, or HAND.

Participants with brain fog had problems such as “remembering recent events, finding names or words, staying focused, and having problems retaining and manipulating information, as well as slow processing speed”, Joanna Hellmuth, MD, the study author and a member of the UCSF Memory and Aging Center, said at a university Press release.

Seventeen participants agreed to have their cerebrospinal fluid analyzed, 13 of them with symptoms of brain fog. Fluid was collected an average of 10 months after the onset of COVID symptoms.

Of the 13 participants with brain fog, 10 of them had abnormalities in their cerebrospinal fluid like those found in people with other infectious diseases, according to the study.

Abnormalities included elevated levels of protein who suggested inflammation and “the presence of unexpected antibodies found in a immune system“, said the press release. These could be “defector” antibodies that attack the body itself, the researchers said.

“It’s possible that the immune system, stimulated by the virus, is functioning in an involuntary pathological way,” Hellmuth said.

Cognitive problems have also been seen in people infected with other viruses, such as HIV, SARS, SEAS, Hepatitis C, and Epstein-Barr, the researchers said.

Participants with thinking problems had an average of 2.5 thought disorder risk factors, including diabetes and high blood pressure, vascular dementia and history of attention deficit hyperactivity disorder (ADHD). According to the study, participants who had no thinking problems had less than one risk factor on average.

Brain fog is often reported in COVID patients, according to the study. Recently, 67% of 156 post-COVID patients in New York City reported having problems thinking.

Limitations of the study included the small sample size, with the researchers calling for more studies on the subject.