Small study finds lower brain blood flow in people with long COVID and persistent fatigue

Karolinska Institutet says researchers compared 22 people with post-COVID condition and 19 controls using brain scans and a 20-minute attention task. The patient group had lower measured brain blood flow, slower reactions and a greater rise in reported fatigue. Their reaction times did not worsen significantly more as the task continued. The researchers caution that the small study cannot establish whether blood-flow differences cause fatigue.