Long COVID is real and the effects are devastating.
For five years, millions of people have carried an illness that medicine could name but not fully explain — a fatigue so deep it felt like disappearing from one's own life. Now, researchers at Toronto's Centre for Addiction and Mental Health have used brain imaging to reveal something concrete and consequential: long COVID physically damages the dopamine-producing neurons that govern motivation, memory, and movement. In placing a measurable biological injury at the center of a condition long shadowed by doubt, science has not only advanced toward treatment — it has offered something rarer still, the dignity of being believed.
- Roughly five percent of the global population, including two million Canadians, remain trapped in long COVID's grip years after infection — fatigued, cognitively impaired, and without a clear biological explanation for their suffering.
- PET brain scans now reveal a direct and measurable loss of dopamine-releasing neurons across the striatum, with the pattern of damage mapping precisely onto each patient's specific symptoms — motivational loss, slowed movement, memory failure.
- The findings close a critical gap: earlier research showed brain inflammation in dopamine-rich regions, but this study provides the first direct evidence that those neurons are actually being damaged or destroyed.
- A clinical trial is being prepared to test whether existing dopamine-augmenting medications can be repurposed to restore memory, motivation, and energy — offering a treatment pathway where none previously existed.
- For patients like Susan Deuville, who spent years seeking validation while watching her former self recede, a visible injury on a brain scan carries a weight beyond medicine — it confirms that what they have endured is undeniably, measurably real.
For five years, Susan Deuville has been searching for an explanation. After contracting COVID-19 in 2021, what followed was not recovery but slow unraveling — a fatigue so complete it felt like living behind glass. She was not alone. Across the world, roughly five percent of the population found themselves similarly trapped in long COVID, a constellation of symptoms persisting long after the initial infection had supposedly cleared.
Now, researchers at the Centre for Addiction and Mental Health in Toronto have identified what may be happening inside those brains. Using positron emission tomography, they discovered that people with long COVID show significantly reduced levels of dopamine-releasing neurons across the striatum — the brain region responsible for motivation, movement, and memory. Published in eBioMedicine, it is the most direct evidence yet of actual physical damage to the brain's dopamine system.
The research team, led by Dr. Jeffrey Meyer, found that the pattern of neuronal damage mapped precisely onto each patient's symptoms. Greatest dopamine loss in the ventral striatum corresponded with the most severe motivational deficits. Damage in the dorsal putamen produced slowed movement. Injury to the caudate putamen aligned with memory problems. This was not a vague association but a direct correspondence between neuronal injury and lived experience.
The findings build on earlier work showing elevated brain inflammation in long COVID patients, particularly in dopamine-rich regions. What had been missing was proof that this inflammation was actually harming those neurons. That proof is now visible on the scan.
The implications reach beyond diagnosis. If long COVID is fundamentally a disorder of the dopamine system, existing medications designed to boost dopamine function could be repurposed as treatments. Meyer's team is already planning a clinical trial, launching in coming months with University Health Network, to test whether dopamine-enhancing drugs can improve memory, motivation, and fatigue.
For Deuville, the research carries a different kind of weight. "It was a crushing loss of the life I had and the person I was before," she said. "The research brings hope. It also validates what long COVID sufferers have always known — long COVID is real and the effects are devastating." A measurable change in brain structure cannot be argued away. It is there on the scan. And now, for the first time, there is a plausible path toward treating it.
For five years, Susan Deuville has been searching for an explanation. In 2021, she contracted COVID-19. What followed was not a recovery but a slow unraveling—a loss of the person she had been, replaced by fatigue so complete it felt like living behind glass. She was not alone. Across the world, roughly five percent of the population, including about two million Canadians, found themselves trapped in a similar condition: long COVID, a constellation of symptoms that persists for months or years after the initial infection has supposedly cleared.
Now, researchers at the Centre for Addiction and Mental Health in Toronto have identified what may be happening inside the brains of people like Deuville. Using positron emission tomography—a specialized imaging technique that can measure the health of individual neuron populations—they discovered something striking: people with long COVID show significantly reduced levels of dopamine-releasing neurons across the striatum, the brain region responsible for motivation, movement, and memory. The study, published in eBioMedicine, represents the most direct evidence yet that long COVID involves actual physical damage to the brain's dopamine system.
The research team, led by Dr. Jeffrey Meyer, a senior scientist at the Brain Health Imaging Centre and Canada Research Chair, compared brain scans from long COVID patients with those of healthy individuals. What they found was consistent and measurable: the dopamine markers were lower across all major regions of the striatum. But more than that, the pattern of damage correlated precisely with the pattern of symptoms. Patients with the greatest loss of dopamine in the ventral striatum—a region tied to motivation—reported the most severe motivational deficits. Those with damage in the dorsal putamen showed slowed movement. Damage in the caudate putamen corresponded with memory problems. The specificity was striking. This was not a vague association but a direct mapping of neuronal injury to lived experience.
The findings build on earlier work by the same team showing that long COVID patients have elevated inflammation in the brain, particularly in regions dense with dopamine neurons. What was missing until now was proof that this inflammation was actually killing or damaging those neurons. "We know that inflammation can injure dopamine neurons," Meyer explained. "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 chain of causation, long suspected, was now visible.
For the millions of people living with long COVID, the implications are profound. Long COVID has been a condition without a clear biological mechanism, which meant it was also a condition without a clear treatment. Doctors could manage symptoms but not address the underlying problem. The new findings suggest a different path forward. If long COVID is fundamentally a disorder of the dopamine system, then existing medications designed to boost dopamine function—dopamine precursors and drugs that slow dopamine breakdown—might be repurposed to help. Meyer and his team are already planning a clinical trial to test this approach, launching in the coming months in collaboration with University Health Network, with a focus on whether dopamine-enhancing medications can improve memory, motivation, and fatigue.
For Deuville, who has spent years seeking answers while watching her life contract around her illness, the research carries a different kind of weight. "It was a crushing loss of the life I had and the person I was before," she said. "The research brings hope. It also validates what long COVID sufferers have always known—long COVID is real and the effects are devastating." The validation matters. Long COVID has been a condition shadowed by skepticism, its sufferers sometimes dismissed as deconditioned or psychologically fragile. A visible, measurable change in brain structure—dopamine neurons actually damaged—cannot be argued away. It is there on the scan. It is real. And now, for the first time, there is a plausible path toward treating it.
Notable Quotes
Long COVID is, at least in part, a disorder of the brain's dopamine system. This suggests that repurposing medications that augment the function of dopamine-releasing neurons could be a promising approach.— Dr. Jeffrey Meyer, Senior Scientist at the Brain Health Imaging Centre
It was a crushing loss of the life I had and the person I was before. The research brings hope. It also validates what long COVID sufferers have always known—long COVID is real and the effects are devastating.— Susan Deuville, lived experience research advisor
The Hearth Conversation Another angle on the story
Why does dopamine matter so much here? It seems like the brain has lots of neurotransmitters.
Dopamine is the motivation molecule. It's what makes you want to do things, what gives movement its fluidity, what anchors memory into place. When it's damaged, you don't just feel tired—you lose the drive to move, to think, to care. That's why the same inflammation that damages dopamine neurons produces such a specific set of symptoms.
So the inflammation was always there. Why is this study different from the earlier work?
Because seeing inflammation and proving it's actually killing neurons are two different things. The earlier study showed the fire. This one shows the burned building. That's the difference between suspicion and evidence.
What happens if the clinical trial works? What would these dopamine medications actually do?
They wouldn't cure long COVID. But they might restore enough dopamine function that people could reclaim their lives—move faster, think clearer, want things again. For someone who's been stuck for five years, that's everything.
Is there a risk these medications could be overprescribed, or misused?
That's a fair concern. But right now, long COVID patients have nothing. A medication that actually addresses the root problem, used carefully and monitored, is better than the current alternative: suffering without explanation.
What about people who had COVID but didn't develop long COVID? Why did their dopamine neurons survive?
That's the next question. The study doesn't answer it. But it's the kind of question that matters—understanding who's vulnerable, why some people's immune systems attack their own neurons and others don't.