Scientists at the Centre for Addiction and Mental Health used a special brain scan called PET to look at people with long COVID. They found strong proof that the virus can hurt brain cells that release dopamine.
Long COVID affects about 5% of people worldwide, roughly two million Canadians. The illness lasts at least three months after the original infection and can cause tiredness, foggy thinking, memory loss, and a low mood.
Brain Scan Shows Dopamine Changes
The PET scan measures a marker that tells how healthy dopamine cells are. Compared with healthy volunteers, people with long COVID had much lower marker levels in the striatum, a part of the brain that controls motivation, movement and thinking.
When the marker was low in the ventral striatum, people felt less motivated. Low levels in the dorsal putamen made movements slower, and reduced marker in the caudate putamen linked to memory problems.
Earlier Work Found Inflammation
Earlier studies from the same team showed that long COVID creates a lot of inflammation in the brain, especially where dopamine cells live. Inflammation can hurt these cells, and the new scan proves that the cells are indeed damaged.
What This Means for Treatment
Most research has focused on brain inflammation and the immune system. Very few trials have looked at dopamine cells directly.
Because dopamine problems seem important, doctors might try medicines that boost dopamine, such as dopamine precursors or drugs that slow dopamine breakdown.
For patients, this offers a clear biological reason for symptoms that feel invisible to others.
Plans for a New Clinical Trial
The researchers will soon start a trial that tests whether improving dopamine function can lift memory, motivation and fatigue in long COVID patients.
The study is a partnership with University Health Network and is funded by the Canadian Institutes of Health Research.