Reorganization of brain connectivity in post-COVID condition A 18F-FDG PET study

Background. A hypometabolic brain pattern has been reported in patients with post-COVID condition. The aim of this study was to investigate reorganization in metabolic connectivity in patients with post-COVID condition (PCC). Results. One hundred eighty-eight patients who underwent brain ¹⁸ F-FDG PET for PCC were retrospectively included from two university hospital centres. These patients were age- and sex-matched to 120 healthy controls who underwent brain ¹⁸ F-FDG PET before the COVID-19 outbreak. A voxel-based group comparison between patients and controls was performed (p-voxel at 0.005 uncorrected, p-cluster at 0.05 FWE corrected). Interregional correlation analyses (IRCA) of the identified clusters as well as sparse inverse covariance estimations (SICEs) at whole-brain scaling were also conducted. Both analyses were performed at the group level for all patients and then secondarily according to the postinfection delay; 88 and 100 patients, respectively, had a delay of less than or greater than 9 months (± 9 M). Three hypometabolic clusters, namely, the right frontotemporal, right and left cerebellar, were identified from the voxel-based group comparisons of PCC patients. Within this hypometabolic PCC pattern, a modification in metabolic connectivity was observed in patients compared with controls, which was more marked in the + 9 M group than in the − 9 M group. On the other hand, the graph analysis revealed a decrease in connectivity efficiency metrics in the PCC. Conclusions. Metabolic connectivity is modified in patients with PCC within the hypometabolic post-COVID-19 network, with lasting reorganization evolving over time, suggesting functional adaptation.