A significant portion of the global population, estimated at roughly five percent including approximately two million Canadians, suffers from long COVID. This condition, characterized by persistent symptoms such as cognitive dysfunction, memory loss, low mood, and extreme fatigue for at least three months post-infection, currently lacks evidence-based treatments due to incomplete understanding of its neurological mechanisms.
Recent research utilizing positron emission tomography (PET) scans has identified substantial reductions in markers associated with dopamine neuron health across key regions of the striatum in patients with long COVID. The striatum plays a critical role in regulating movement, thinking, and motivation. The study found that varying degrees of dopamine marker loss correlated with specific symptoms: reduced activity in the ventral striatum was linked to diminished motivation, while changes in the dorsal putamen and caudate putamen were associated with slower motor function and memory deficits, respectively.
Dr. Jeffrey Meyer, Senior Scientist at the Brain Health Imaging Centre and senior author of the study, stated that the findings provide compelling evidence that long COVID involves the loss of dopamine-releasing neurons. This aligns with previous work by the same team showing elevated brain inflammation in regions rich in dopamine neurons, suggesting a causal link between persistent inflammation and subsequent dopamine system damage.
These results may shift the focus of future treatments. While earlier research emphasized immune activity and inflammation, the new data indicates that repurposing medications to support dopamine function could be a viable therapeutic approach. Susan Deuville, a lived experience research advisor who contracted COVID in 2021, noted that the findings validate the experiences of sufferers and offer hope for effective interventions.
Building on this evidence, researchers plan to launch a clinical trial within the next few months in collaboration with the University Health Network (UHN). Supported by the Canadian Institutes of Health Research (CIHR), the trial aims to determine whether modifying dopamine activity can improve memory, motivation, and fatigue in long COVID patients.
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