Cognitive symptoms experienced by people recovering from COVID-19 may be linked to abnormalities found in cerebrospinal fluid, new research has revealed.
The new findings around the role of cerebrospinal fluid, which saw similar changes in those recovering from a mild bout of COVID as people with other infectious diseases, may provide new insight into how the SARS-CoV-2 virus impacts the brain.
‘Brain fog’ has become recognised as a common after effect of COVID and symptom of Long COVID, which can cause varying degrees of cognitive issues.
In a small study with 32 adults, comprising 22 with cognitive symptoms and ten control participants without, researchers from UC San Francisco and Weill Cornell Medicine, New York, analysed the cerebrospinal fluid of 17 of the participants who consented to lumbar puncture.
All participants had had COVID but had not required hospitalisation.
They found that ten of 13 participants with cognitive symptoms had anomalies in their cerebrospinal fluid – but all four of the cerebrospinal samples from participants with no post-COVID cognitive symptoms were normal.
Participants with these symptoms presented with executive functioning issues, said senior author Dr Joanna Hellmuth, of the UCSF Memory and Aging Center.
“They 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,” she said.
Examinations of the cerebrospinal fluid revealed elevated levels of protein, suggesting inflammation, and the presence of unexpected antibodies found in an activated immune system.
Some were found in the blood and cerebrospinal fluid, implying a systemic inflammatory response, or were unique to the cerebrospinal fluid, suggesting brain inflammation.
While the targets of these antibodies are unknown, it is possible that these could be “turncoat” antibodies that attack the body itself.
“It’s possible that the immune system, stimulated by the virus, may be functioning in an unintended pathological way,” said Dr Hellmuth, who is principal investigator of the UCSF Coronavirus Neurocognitive Study and is also affiliated with the UCSF Weill Institute for Neurosciences.
“This would be the case even though the individuals did not have the virus in their bodies,” she said, noting that the lumbar punctures took place on average ten months after the participants’ first COVID symptom.
The researchers also found that the participants with cognitive symptoms had an average of 2.5 cognitive risk-factors, compared with an average of less than one risk factor for participants without the symptoms.
These risk-factors included diabetes and hypertension, which can increase the risk of stroke, mild cognitive impairment and vascular dementia; and a history of ADHD, which may make the brain more vulnerable to executive functioning issues. Other risk factors included anxiety, depression, a history of heavy alcohol or repeated stimulant use, and learning disabilities.
