Long COVID Fatigue May Be Linked to Reduced Blood Flow in the Brain

A small study conducted at Karolinska Institutet in Stockholm suggests that reduced blood flow in the brain may contribute to cognitive fatigue and difficulty concentrating experienced by some people who have recovered from COVID-19. The researchers examined 22 patients with mild cases of COVID-19 who had been infected between 2020 and 2021, and compared them to 19 healthy volunteers.

After completing a vigilance task in an MRI scanner, the patients reported significantly more fatigue than the volunteers, even after accounting for the demands of the task. Brain scans revealed that the patients had 4.8% lower blood flow in the brain's gray matter, with the most significant differences in areas related to vision, movement coordination, and attention and emotion.

The slower reaction times of the patients correlated with lower blood flow, indicating a possible link between reduced blood flow and cognitive difficulties. However, the study's small sample size and lack of control over factors such as anxiety and depression limit its ability to establish a definitive cause-and-effect relationship between blood flow changes and long COVID fatigue. More research is needed to confirm these findings and determine their clinical implications.