Brain fog. It has become an inexplicable side effect of this pandemic, but researchers now report they have discovered a possible reason why it happens.
In a small study, investigators found abnormalities in the cerebrospinal fluid of some patients who developed thinking problems during the pandemic.
The symptoms “manifest as problems remembering recent events, coming up with names or words, staying focused, and issues with holding onto and manipulating information, as well as slowed processing speed,” explained study senior author, Dr. Joanna Hellmuth, from the Memory and Aging Center at the University of California, San Francisco.
A recent study found that brain fog is a common aftereffect of infection, striking about 67% of 156 patients at a clinic in New York.
In this latest study, the researchers analyzed the cerebrospinal fluid of 13 people who had thinking and memory problems after contracting the disease, and 4 recovered patients with no cognitive symptoms.
The average age of those with cognitive symptoms was 48, compared with 39 for those with no cognitive symptoms. The cerebrospinal fluid samples were collected an average of 10 months after the patients’ first symptoms. None of the patients were hospitalized for the disease.
Cerebrospinal fluid anomalies were found in 10 of the 13 patients with cognitive symptoms, but not in any of the 4 with no cognitive symptoms, according to the study published in the journal Annals of Clinical and Translational Neurology.
The cerebrospinal fluid of patients with cognitive symptoms had elevated protein levels, suggesting inflammation and unexpected antibodies found in an activated immune system.
Some of those antibodies were found in both cerebrospinal fluid and blood, indicating a systemic inflammatory response, or were found only in cerebrospinal fluid, suggesting brain inflammation.
While the targets of these antibodies are unknown, they could be “turncoat” antibodies that attack the body itself, according to the researchers.
“It’s possible that the immune system, stimulated by the [infection], may be functioning in an unintended pathological way,” said Hellmuth, principal investigator of the UCSF Coronavirus Neurocognitive Study and affiliated with the UCSF Weill Institute for Neurosciences.
The study also found that participants with thinking problems had an average of 2.5 risk factors for impaired thinking, compared with an average of less than 1 risk factor for participants without the symptoms.
Those risk factors included: diabetes and high blood pressure, which can increase the risk of stroke, mild cognitive impairment, and vascular dementia; a history of attention deficit hyperactivity disorder (ADHD), which may make the brain more vulnerable to executive functioning issues; anxiety; [a mood disorder]; a history of heavy alcohol or repeated stimulant use; and learning disabilities.
More information
For more on pandemic brain fog, go to Harvard Medical School.
SOURCE: University of California, San Francisco, news release, Jan. 18, 2022
