Brain F-FDG-PET abnormalities and their associations with neuropsychological assessment in initially hospitalized patients with post-COVID-19 conditions: a prospective and longitudinal study.

Rationale: This study aims to longitudinally investigate the associations between brain F-FDG-PET metabolism and neuropsychological assessment (NPA) in initially hospitalized patients with post-COVID-19 conditions (PCCs).

Methods: Patients with PCC and confirmed neurological impairment were prospectively included and underwent both brain F-FDG-PET and NPA at inclusion and one year later. BrainF-FDG-PET metabolism was correlated with NPA tests. The identified hypometabolic clusters after quantitative voxel-by-voxel group analyses were correlated with the NPA results.

Results: Twenty-three patients (51.0 ± 9.5 years; 9 women) were included. Brain F-FDG-PET metabolism was correlated with the results of the Hamilton Anxiety Rating Scale (HARS), episodic memory, executive function and autonomy tests (p-voxel < 0.005; p-cluster < 0.05 uncorrected). Two cerebellar hypometabolic clusters were found in patients with PCC at inclusion and one year later (n = 16, p-voxel < 0.005; p-cluster < 0.05 corrected). Cerebellar metabolism was associated with an abnormal HARS test at one year (p ≤ 0.04) but not at inclusion. At one year, no brain metabolic recovery and no significant improvement in NPA tests were observed.

Conclusion: Brain F-FDG-PET metabolism is associated with the results of neuropsychological tests in initially hospitalized patients with PCC, especially the metabolism of the cerebellum, which was found to be decreased in patients, and symptoms of anxiety experienced by patients. Similarly, brain F-FDG-PET hypometabolism and impairment in NPA tests did not significantly improve one year later.