Exploring the Underlying Mechanisms of Chronic Cerebral Blood Flow Deficits in Covid-19

Motivation: The underlying mechanisms of reduced cerebral blood flow (CBF) in COVID-19 remain unclear. Goal(s): To explore if altered microvascular architecture or acute inflammation and coagulation underly chronically reduced CBF. Approach: Global and capillary CBF and vessel architecture imaging (VAI) measures (vessel density and size) were compared between COVID-19 and non-COVID intensive care unit (ICU) survivors, and healthy controls. Within COVID-19 survivors, CBF measures were correlated with acute inflammation and coagulation. Results: Lower global and capillary CBF was observed in ICU survivors compared to healthy controls, in absence of altered VAI. In COVID-19, lower capillary CBF correlated with acute coagulation. Impact: Our findings suggest that chronically reduced CBF was not accompanied by altered microvascular architecture. Chronically reduced capillary perfusion was, however, preceded by hypercoagulation during the ICU period. The observed CBF deficits do not seem COVID-19-specific.