Brain Scans Show Why Long COVID Causes Fatigue and Brain Fog

Scientists just found what might be the missing puzzle piece in understanding long COVID, and it could change everything for two million Canadians still struggling with symptoms years after infection.

Researchers at the Centre for Addiction and Mental Health in Toronto used brain imaging technology to discover that long COVID damages the neurons that release dopamine, a crucial brain chemical. The finding explains why people with long COVID experience persistent fatigue, brain fog, memory problems, and loss of motivation.

The study used PET scans to examine the brains of long COVID patients compared to healthy people. The results showed substantially lower levels of dopamine markers across major brain regions that control motivation, movement, and thinking.

Here's where it gets really interesting: different patterns of damage matched different symptoms. Lower dopamine levels in one brain region linked to motivation problems, while reductions in another area connected to slower movement and memory difficulties.

"Our findings provide compelling evidence that long COVID involves the loss of dopamine-releasing neurons," says Dr. Jeffrey Meyer, who led the study published in eBioMedicine. This kind of brain injury is known to cause lack of motivation and slower movement in other conditions.

The discovery builds on earlier research showing unusually high inflammation in the same brain regions. Together, the studies suggest that persistent inflammation after COVID infection injures the dopamine system, creating the symptoms that disrupt daily life.

The Bright Side

For the first time, doctors have a clear biological target for treatment. Most long COVID research has focused on inflammation alone, but very few clinical trials have tested medications that support dopamine function directly.

The research team plans to start a clinical trial within months testing whether dopamine-boosting medications can improve memory, motivation, and fatigue in long COVID patients. They're exploring repurposed drugs that help dopamine neurons work better, including dopamine precursors and metabolism inhibitors.

For Susan Deuville, who contracted COVID in 2021 and advised on the research, the findings bring something precious: validation. "For five years I have been seeking answers on what happened to me," she says. "The research brings hope. It also validates what long COVID sufferers have always known: long COVID is real and the effects are devastating."

About five percent of the global population lives with long COVID, dealing with symptoms lasting at least three months after infection. Until now, there have been no evidence-based treatments, partly because scientists didn't fully understand what was happening in the brain.

This breakthrough transforms long COVID from a mysterious condition into one with a measurable cause and a path forward for treatment.