New Studies Link Long COVID Fatigue to Reduced Brain Blood Flow and Dopamine Neuron Loss

Key points

• A study from Karolinska Institutet found that 22 long COVID patients with persistent fatigue exhibited lower overall cerebral blood flow compared to 19 healthy controls.
• Reduced blood flow in regions governing attention and cognitive control was associated with slower reaction times and increased fatigue ratings during sustained attention tasks.
• A separate Canadian study using PET scans detected significantly lower markers of dopamine neuron integrity in the striatum of long COVID patients.
• The Canadian research linked reduced dopamine markers in the ventral striatum to loss of motivation, the dorsal putamen to slower movement, and the caudate putamen to memory difficulties.
• Researchers note that while these findings show associations, they do not yet prove causation, and larger longitudinal studies are needed to confirm if these biological changes directly drive symptoms.

Background

Recent research has highlighted various neurological and immune-related changes in long COVID. Earlier findings indicated that inflammation can injure dopamine neurons, while other studies have explored how dormant virus reactivation and midlife immune shifts may contribute to chronic symptoms. The current studies add neurovascular and dopaminergic evidence to the complex picture of post-COVID conditions.

How outlets are covering it

The Conversation emphasizes the role of cerebral blood flow, noting that reduced perfusion in specific brain areas correlates with subjective fatigue and performance metrics, though it cautions that the small sample size limits causal conclusions. Qazinform highlights a dopamine-centric view, reporting that the loss of dopamine-releasing neurons in the striatum explains a range of symptoms including motivation and movement issues. While The Conversation focuses on vascular mechanisms and attention deficits, Qazinform focuses on neurochemical degradation and potential therapeutic targets for dopamine function. Both outlets agree that these biological changes are associated with, but not yet proven to cause, the symptoms of long COVID.

Why it matters

Identifying specific biological markers like reduced blood flow and dopamine neuron loss provides a clearer understanding of why long COVID affects daily functioning. These insights may lead to targeted treatments, such as dopamine-boosting therapies or interventions to improve cerebral circulation, for patients suffering from persistent fatigue and cognitive difficulties.

What to watch

Researchers plan to launch a clinical trial with University Health Network to test whether medications that strengthen dopamine function can improve fatigue, memory, and motivation in long COVID patients. Additionally, larger studies are needed to determine if the observed reductions in cerebral blood flow are a cause or a consequence of the condition, and whether these markers can be used for clinical diagnosis.