A new brain imaging study led by researchers at the Canadian Centre for Addiction and Mental Health (CAMH), published in eBioMedicine, provides the strongest evidence to date that Long Covid is associated with injury to dopamine-releasing neurons in the brain.
Summary
- A new CAMH (Canada) study published in eBioMedicine found strong evidence that long Covid is associated with damage to dopamine-releasing neurons in the brain, helping explain symptoms such as fatigue, slowed movement, and memory problems.
- Using PET brain imaging, researchers found significantly reduced dopamine neuron markers in key brain regions of people with Long Covid compared with healthy individuals. Lower dopamine levels were linked to more severe symptoms.
- The findings build on previous research showing brain inflammation in Long Covid, suggesting inflammation may contribute to dopamine neuron damage.
- The study indicates that disrupted dopamine function may be a key feature of Long Covid, providing new insight into the biological basis of the condition.
- Researchers suggest that existing medications that enhance dopamine function could be repurposed as potential treatments for Long Covid symptoms.
- Based on these findings, the team plans to launch a clinical trial in collaboration with University Health Network (UHN) to test dopamine-targeting treatments for fatigue and memory problems
Extracts
In the new study, researchers used positron emission tomography (PET) brain imaging to measure a well-established marker of dopamine neuron integrity in people with long COVID and healthy individuals.
The team found significantly lower levels of the imaging marker—indicating reduced dopamine nerve terminal density—across all major regions of the striatum, the brain structure that plays a central role in motivation, movement, and thinking, in people with long COVID compared to healthy individuals.
MEA Comment
Dopamine is an important brain chemical (neurotransmitter) that helps to regulate a wide range of body functions including movement, memory and attention, sleep, and learning.
As a hormone, dopamine is released into the bloodstream where it has a role in the “fight-or-flight” response to stressful situations.
Dopamine also causes blood vessels to relax (at low doses, it acts as a vasodilator) or constrict (at high doses, it acts as a vasoconstrictor), slows gastrointestinal content movement and and reduces lymphocyte (white blood cell) activity in your immune system.
So, there are theoretical reasons why changes in dopamine production could be involved in both Long Covid and ME/CFS – where previous research has also queried a link.
While this new research, which found damage to the dopamine nerve pathways in Long Covid, provides some support for this hypothesis it's too early to draw any firm conclusions, especially in relation to the possible use of drugs that are already being used to treat conditions such as Parkinson's disease where an abnormality in dopamine production is well established.
Dr Charles Shepherd,
Trustee and Hon. Medical Adviser to the ME Association,
Member of the 2018-2021 NICE guideline on ME/CFS committee,
Member of the 2002 Chief Medical Officer's Working Group on ME/CFS
