A new PET brain imaging study led by the Centre for Addiction and Mental Health (CAMH) in Toronto offers the strongest evidence yet that long COVID is linked to damage in the brain's dopamine-releasing neurons.
The Research
Published in eBioMedicine in September 2026, the study compared people with long COVID to healthy participants using positron emission tomography (PET) — an imaging method that measures biological activity inside the brain. The team focused on a well-established marker tied to the health and integrity of dopamine neurons.
They found substantially lower levels of this marker in people with long COVID across all major areas of the striatum, a cluster of brain regions involved in motivation, movement, and thinking. Lower marker levels suggest a reduced density of dopamine nerve terminals.
Different patterns of loss matched different symptoms. Reduced levels in the ventral striatum were linked to greater loss of motivation. Lower levels in the dorsal putamen were associated with slower movement, while drops in the caudate putamen connected to memory difficulties.
"Our findings provide compelling evidence that long COVID involves the loss of dopamine-releasing neurons," said Dr. Jeffrey Meyer, Senior Scientist at the Brain Health Imaging Centre, Canada Research Chair, and senior author of the study. "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."
The findings build on earlier work from the same team showing unusually high brain inflammation in long COVID, especially in regions dense with dopamine neurons. "We know that inflammation can injure dopamine neurons," Meyer said. "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."
Long COVID affects roughly five per cent of the global population, including about two million people in Canada. Symptoms persist at least three months after initial infection.
Why It Matters
Dopamine is not just a "reward chemical" — it helps drive motivation, initiate movement, and support working memory. When dopamine terminals are lost, everyday tasks can feel draining, and thinking can slow down. This study offers a biological explanation for symptoms that are often hard to measure.
Critically, the results suggest long COVID is at least partly a disorder of the dopamine system, opening a new direction for treatment. Most prior research focused on brain inflammation and immune activity; very few clinical trials have targeted dopamine neurons directly.
What You Can Do
If you're recovering from long COVID and notice persistent fatigue, low motivation, or memory slips, these findings are a reason to talk with a clinician rather than push through silently. Keep a simple symptom log — note when motivation, movement speed, and memory feel worst — to bring concrete patterns to your appointment. For anyone tracking their own cognition, regular check-ins with attention and memory tasks can help you notice changes over time. This study doesn't prove any treatment works, but it points researchers toward dopamine-related options that deserve testing.
Source: ScienceDaily Mind & Brain
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