Brain scans reveal a possible cause of long COVID fatigue and brain fog

Researchers have found evidence that long COVID may damage dopamine releasing neurons in the brain, potentially explaining persistent fatigue, low motivation, slowed movement, and memory difficulties. The discovery could lead to new treatments that target the brain's dopamine system. A new brain imaging study led by scientists at the Centre for Addiction and Mental Health (CAMH) has uncovered what researchers describe as the strongest evidence so far that long COVID is associated with damage to dopamine-releasing neurons in the brain. Published in eBioMedicine, the findings could help explain persistent problems such as fatigue-related loss of motivation, slower movement, and memory difficulties. They may also point toward new treatment strategies.

Long COVID is estimated to affect about five per cent of the global population, including roughly two million people in Canada. The condition can involve a broad range of symptoms that continue for at least three months after the initial COVID-19 infection. Common brain-related symptoms include fatigue, brain fog, memory problems, and low mood. Despite how widespread and disruptive long COVID can be, there are currently no evidence-based treatments, in part because scientists still do not fully understand what is happening in the brain. For the new study, researchers used positron emission tomography (PET), an imaging technique that can measure biological activity inside the brain. They examined a well-established marker associated