Brain injury a common consequence of both COVID-19 and influenza Brain Influenza Coronavirus Disease COVID19 Neurology Brain1878 Cambridge_Uni
COVID-19 has been linked to neurologic complications such as stroke, autoimmune encephalitis, and Guillain-Barré syndrome. While physical brain injury is evident in COVID-19-related neurologic syndromes such as encephalitis and stroke, various reports suggest COVID-19-associated brain injury could occur even in the absence of a concomitant neurologic diagnosis. In addition, the exaggerated inflammatory response during COVID-19 might drive progression to severe disease.
Healthy subjects were recruited before the COVID-19 pandemic as controls. Stored clinical and plasma data of influenza patients from a separate trial were used as an additional control cohort. A small positive control group was included as a reference for the magnitude of elevations of brain injury biomarkers. This group comprised patients with acute severe traumatic brain injury.
Findings The researchers obtained 250 samples from 175 COVID-19 patients and control samples from 59 healthy subjects and 45 influenza patients. Seventy COVID-19 patients had mild disease, 72 had moderate disease, and 33 patients had severe disease. The concentrations of GFAP, total tau, and NfL were above the functional lower limit of quantification for most healthy control and COVID-19 patient samples.
The increase in total tau concentration did not vary with disease severity. Convalescent levels of serum GFAP and NfL correlated with paired samples collected between 15 and 42 days, whereas total tau concentrations did not correlate. Moreover, GFAP and NfL concentrations in the plasma collected from influenza patients with severe disease were elevated to levels comparable to COVID-19 patients.
Increased serum cytokine levels were observed in sub-acute samples, and many convalescent samples had elevated cytokine concentrations above the normal range. Moderate and severe COVID-19 patients had elevated levels of proinflammatory cytokines. Next, the team investigated the associations between brain injury biomarkers and inflammatory profiles .