Brain scans reveal a possible cause of long COVID fatigue and brain fog

A new brain imaging study led by scientists at the Centre for Addiction and Mental Health has uncovered strong evidence that long COVID may be linked to damage in dopamine-releasing neurons in the brain. This research, published in eBioMedicine, could help explain persistent symptoms such as fatigue, slowed movement, and memory issues, and may pave the way for new treatments.

Long COVID affects roughly five percent of the global population, including about two million Canadians. Symptoms include fatigue, brain fog, memory problems, and low mood. The study used positron emission tomography (PET) to measure biological activity in the brain and found significantly lower levels of a dopamine neuron marker in those with long COVID across major striatum areas.

The striatum regulates motivation, movement, and thinking. Different marker reductions correlated with specific symptoms: lower ventral striatum levels linked to reduced motivation, diminished dorsal putamen to slower movement, and lower caudate putamen to memory difficulties. Dr. Jeffrey Meyer, the study's senior author, explains that this injury produces lack of motivation, motor slowing, and memory problems seen in neurological conditions.

He suggests these findings indicate long COVID involves a dopamine system disorder, pointing to potential treatments like medications augmenting dopamine-releasing neuron function. The researchers plan to start a clinical trial to test if modifying dopamine activity can improve memory, motivation, and fatigue in long COVID patients.