Scientists Find Brain Scan Clues Behind Long COVID Fatigue and Brain Fog
Long COVID may be associated with damage to the brain's dopamine system, potentially helping explain persistent symptoms such as fatigue, reduced motivation, slower movement and memory problems, according to a new brain imaging study.
Published in eBioMedicine, the study by researchers at the Centre for Addiction and Mental Health used positron emission tomography (PET) scans to examine dopamine-related changes in people with long COVID. The researchers compared a marker of dopamine nerve-terminal health with findings from healthy participants.
They found substantially lower levels of the marker across major regions of the striatum, a group of brain structures involved in motivation, movement and thinking. Lower levels of the marker suggest reduced density of dopamine nerve terminals.
The researchers also found that changes in different areas were associated with specific symptoms. Lower marker levels in the ventral striatum were linked to greater loss of motivation, while reductions in the dorsal putamen were associated with slower movement. Changes involving the caudate and putamen were also associated with memory difficulties.
The findings build on earlier research from the same team showing increased brain inflammation in people with long COVID, particularly in regions containing dopamine-releasing neurons. Researchers said inflammation could potentially contribute to injury of these neurons, although the new study does not establish that inflammation directly causes dopamine-system damage.
The researchers suggested that the findings could help guide future treatment research, including studies of medicines that increase or preserve dopamine activity. However, such treatments have not yet been established as effective for long COVID.
The study provides evidence of an association between long COVID and changes in dopamine-related brain structures, but further research is needed to confirm the findings and determine their clinical significance.
REFERENCE: Yuhan Karida Liu, et al.; Loss of vesicular monoamine transporter 2 in striatum of long COVID and relationship to neuropsychiatric symptoms. eBioMedicine, 2026; 130: 106339 DOI: 10.1016/j.ebiom.2026.106339
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