(Medford MA, October 21, 2023) – Brain inflammation (neuroinflammation) has been proposed as a driver of Long COVID symptoms. However, no research team has yet formally documented neuroinflammation in patients with diverse Long COVID symptoms. That changed today when PolyBio co-founder Dr. Michael VanElzakker and team at the Harvard/MIT Martinos Center for Biomedical Imaging published a preprint with the results of a high-resolution Long COVID imaging study. The team identified neuroinflammation across a wide range of brain regions in Long COVID patients relative to healthy controls. They additionally found that neuroinflammation positively correlated with blood measures related to vascular dysfunction. The study is supported via PolyBio’s Long Covid Research Consortium.
More specifically, the team used a neuroimaging method called position emission tomography (PET) to measure neuroimmune activation in the brains of Long COVID study participants. This neuroimmune activation can reflect activity of glial cells or inflammatory activation of the brain’s blood vessels, both of which can be components of neuroinflammation.
As a group, the Long COVID patients had more of the PET signal demonstrating neuroinflammation when compared to healthy study participants. Interestingly, this neuroinflammation was located in some brain areas that are exposed to circulating blood factors via normal anatomical gaps in the specialized “blood-brain barrier” of the brain’s blood vessels.
This finding inspired the team to measure a selection of vascular health-related factors in the blood of the Long COVID study participants, which was collected immediately before their scans. They found that six vascular factors including fibrinogen and L-selectin were significantly correlated with neuroinflammation in the Long COVID group. “This suggests that the neuroinflammation in Long COVID patients may be connected to vascular problems,” said study principal investigator Dr. Michael VanElzakker.
Indeed, other research teams have found SARS-CoV-2 spike protein or microclots in Long COVID blood that might be reaching parts of the brain and driving inflammation. “A better understanding of these potential sources of neuroinflammation would be important for guiding related treatments and clinical trials” says Hannah Bues, the study’s clinical research coordinator.
Dr. VanElzakker and team have several other studies underway to probe connections between vascular damage, clotting, immune activation, and SARS-CoV-2 persistence in Long COVID, including extended analyses of their PET neuroimaging participants. The team is also running a similar PET imaging study in patients with ME/CFS, so that comparison of neuroinflammation and vascular factors between the patients with the two related diagnoses can be compared.