New PET findings could change how long COVID is treated
New PET imaging findings could help explain why some patients continue to experience lingering side effects from long COVID.
The analysis, which is published in eBioMedicine, indicates that individuals who have been diagnosed with the disease display significantly decreased dopamine neuron integrity on brain scans. Experts believe this could have something to do with why many continue to struggle with fatigue and lack of focus and motivation.
“Our findings provide compelling evidence that long COVID involves the loss of dopamine-releasing neurons,” said study author Jeffrey Meyer, MD, PhD, senior scientist at the Brain Health Imaging Center in Toronto. “This kind of injury is well known to produce symptoms like lack of motivation and motor slowing, and may contribute to memory difficulties in other neurological conditions. Our results suggest a similar process is occurring in long COVID.”
Researchers used PET imaging to compare the presence of dopamine-releasing neurons among healthy individuals and those who have been diagnosed with long COVID. Using (+)[11C]DTBZ, the team targeted vesicular monoamine transporter 2 (VMAT2) binding, which plays a critical role in transporting dopamine to vesicles.
The COVID group showed significantly lower levels of the imaging marker across all major regions of the striatum. This, researchers explained, indicates reduced dopamine nerve terminal density. Such findings were most evident in the ventral striatum, dorsal putamen and caudate putamen, which each play a role in motivation, fatigue and memory. The study's findings could be attributed to the inflammatory effects of COVID.
“We know that inflammation can injure dopamine neurons,” Meyer noted. “While our earlier research showed high-levels of inflammation in those regions, this study provides direct evidence that the dopamine neuron marker is reduced in the same regions—and that this loss correlates with patients’ symptoms.”
The team suggested that their findings alter how COVID-induced brain damage is perceived among providers. Their hope is that it will lead to more effective treatments for individuals who continue to struggle with long-term symptoms.
“These results indicate that long COVID is, at least in part, a disorder of the brain’s dopamine system,” Meyer said. “This suggests that repurposing medications that augment the function of dopamine-releasing neurons, including dopamine precursors and inhibitors of dopamine metabolism, could be a promising approach.”
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In addition to her background in journalism, Hannah also has patient-facing experience in clinical settings, having spent more than 12 years working as a registered rad tech. She began covering the medical imaging industry for Innovate Healthcare in 2021.