Brain News – A study explores cognitive problems developing in Long COVID. It clubs such developments as “brain fog” and attributes them to a disrupted immune system in the post-recovery period.
A study links the development of persistent cognitive symptoms to an overstimulated immune system in Long COVID, which is also called post-acute sequelae SARS-CoV-2 infection (PASC).
The researchers at University of California, San Francisco, enrolled all participants in the Long-term Impact of Infection with Novel Coronavirus (LIINC) study. 32 adults were studied in an out-patient setting. The small group comprised 22 PASC patients with cognitive symptoms and 10 control participants without symptoms. All the participants had a history of mild COVID, without hospitalization or significant medical complications. The researchers performed structured neurocognitive interviews and neuropsychological testing on all the participants. Optional lumbar puncture (LP) for cerebrospinal fluid (CSF) collection was performed solely for 17 consenting individuals. Lastly, all participants underwent an in-person cognitive testing battery, applying equivalent criteria used for HIV-associated neurocognitive disorder (HAND).
The findings, published in Annals of Clinical and Translational Neurology, reveal that 10 of 13 non-hospitalized PASC participants had anomalies in their cerebrospinal fluid. But the cerebrospinal samples of the four control participants were normal. Further examination of the cerebrospinal fluid and blood revealed elevated levels of protein and a huge presence of antibodies—suggesting a systemic inflammatory response in the body in PASC. This condition, the study contends, induces “brain fog” in the afflicted and gets manifested as cognitive problems. This corroborates the Long COVID participants’ testimonies of weaknesses in attention and memory. Moreover, participants with delayed onset of cognitive PASC were found to be younger than those with acute onset of cognitive PASC, with no differences in the presence of specific cognitive risk factors.
The researchers attributed brain fog to brain inflammation caused by a disrupted immune system. Upon the onset of Long Covid, the immune system started to act pathologically and produced “turncoat” antibodies that started attacking the body itself. They also found that PASC patients with the cognitive symptoms were more susceptible to an average of 2.5 cognitive risk-factors, including diabetes, heart diseases, HIV, mental disorders, etc.
Research shows cognitive symptoms have been identified in viral-infections caused by HIV, SARS and MERS, hepatitis C, and Epstein-Barr virus. However, this study is a novelty, for it examines the little-known pathogenesis of ‘baseline’ cognitive PASC and its ‘subtle’ ability to lead to severe diseases in the long-term.
The senior author of the study, Joanna Hellmuth, said, “If people tell us they have new thinking and memory issues, I think we should believe them rather than require that they meet certain severity criteria.”
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Apple, A. C., Oddi, A., Peluso, M. J., Asken, B. M., Henrich, T. J., Kelly, J. D., Pleasure, S. J., Deeks, S. G., Allen, I. E., Martin, J. N., Ndhlovu, L. C., Miller, B. L., Stephens, M. L., & Hellmuth, J. (2022). Risk factors and abnormal cerebrospinal fluid associate with cognitive symptoms after mild COVID-19. Annals of clinical and translational neurology, 10.1002/acn3.51498. Advance online publication. https://doi.org/10.1002/acn3.51498