Researchers at the University of Toronto using PET imaging discovered that long COVID patients have significantly reduced dopamine-releasing nerve terminals in brain regions linked to motivation, memory, and movement, providing the first biological marker for the condition. The finding, led by psychiatry professor Jeffrey Meyer, shows a strong correlation between dopamine loss and specific symptoms like brain fog and fatigue, potentially opening pathways for targeted treatments.
A study of 227 individuals with Long COVID-related neurocognitive symptoms found a 59% increase in plasma pTau-181, a protein biomarker linked to Alzheimer's disease and neurodegeneration, compared to pre-COVID levels and unaffected controls. Elevated tau levels were most pronounced in patients with symptoms lasting over 1.5 years, suggesting prolonged neurological injury, though researchers caution that further studies are needed to determine if this reflects progressive brain pathology or increased dementia risk.