Cognitive fatigue is related to reduced cerebral perfusion and sustained attention in patients with post COVID-19 condition: An fMRI study.

Persistent fatigue is one of the most prevalent and disabling symptoms of Post-COVID-19 Condition (PCC). To investigate possible mechanisms underlying fatigue in PCC, the present study investigated the relation between different aspects of fatigue and fatigability, and cerebral blood flow (CBF) in individuals with PCC. The participants, 22 patients and 19 controls, matched by age and sex, performed a 20-min-long psychomotor vigilance task (PVT) during fMRI. The total mean reaction time (RT) was used to measure processing speed and fatigability by dividing RTs into quartiles. CBF was measured with pseudo-continuous arterial spin labeling. Self-reported state fatigue (VAS-scale) was assessed before and after the PVT. Patients reported larger increase in state fatigue (p = 0.004) and longer RTs across all quartiles (p = 0.001) compared to controls, with no difference in fatigability between groups. The voxel-wise analysis of CBF revealed significantly lower global CBF in patients compared with controls (49.2 vs. 51.7 mL/100 g/min). Regional hypoperfusion was observed in several clusters, including the right inferior occipital gyrus (27.9 vs. 46.4 mL/100 g/min), left postcentral gyrus (29.8 vs. 51.3 mL/100 g/min), and right middle cingulate cortex (30.5 vs. 48.7 mL/100 g/min).