early research suggests. Investigators found abnormalities in cerebrospinal fluid (CSF) and other risk factors, including diabetes and hypertension, present in individuals with mild COVID-19 experiencing persistent cognitive problems, often referred to as “brain fog.”
“We’re seeing changes to the [CSF] in the brain of most people who report cognitive changes,” said Joanna Hellmuth, MD, assistant professor of neurology, Memory and Aging Center, University of California, San Francisco. “We’re just in the beginning stages, but I hope this study will provide some legitimacy to this being a true neurologic condition.”
The study was published online Jan. 18, 2022, in Annals of Clinical and Translational Neurology.
No guidance
There is currently no guidance on how to identify patients with COVID-related cognitive changes, said Dr. Hellmuth. “The term ‘brain fog’ is not based in science or medicine, but that’s the most common term we use to describe this.”
The analysis included adults with confirmed SARS-CoV-2 infection not requiring hospitalization who were enrolled in the Long-term Impact of Infection with Novel Coronavirus study.
Participants underwent a structured interview that covered COVID-19 illness, past medical history, preexisting cognitive risk factors, medications, and cognitive symptoms following onset of COVID-19. They also completed an in-person battery of cognitive tests.
The analysis included 22 participants with at least one new cognitive symptom who had cognitive post-acute sequelae of SARS-CoV-2 infection (PASC). Ten cognitive controls reported no new cognitive symptoms after acute infection.
Participants were a median age of 41 years, had a median of 16 years of education, and were assessed a median of 10.1 months from their first COVID-19 symptom. There were no group differences in terms of age, gender, years of education, or distribution of race/ethnicity (all P > .05).
Among those with cognitive PASC, 43% reported cognitive symptoms starting 1 or more months after the first COVID symptom. About 29% reported cognitive changes started 2 or more months after their first COVID symptom.
“The immune system could be altered in some way after the infection, and perhaps that’s what’s contributing to these delayed onset cognitive changes,” said Dr. Hellmuth.
Compared with controls, participants with cognitive PASC had more preexisting cognitive risk factors (a median of 2.5 vs. 0; P = .03). These included hypertension and diabetes, which increase the risk of stroke, mild cognitive impairment, vascular dementia, traumatic brain injury, (TBI), learning disabilities, anxiety, depression, stimulant use, and ADHD, which may make the brain more vulnerable to executive functioning problems.
Dr. Hellmuth noted that the study wasn’t powered to determine whether any individual risk factor was associated with risk of cognitive changes.
As there are no published neuropsychological testing criteria for cognitive PASC, the researchers applied the equivalent criteria for HIV-associated neurocognitive disorder (HAND), a similar, virally associated cognitive disorder. Only 59% of those with cognitive PASC met equivalent HAND criteria for objective cognitive impairment versus 70% of cognitive controls. This, the investigators noted, highlights “the challenges and incongruities of using subjective, versus objective cognitive assessments for diagnosis.”