Brain Fog and Loss of Motivation: Scientists Identify a Possible Cause of Long COVID Symptoms

Scientists have identified a possible link between long COVID and damage to the brain's dopamine-producing neurons. A new study by researchers at the Centre for Addiction and Mental Health (CAMH) in Canada found that people with post-COVID syndrome have a reduced density of dopamine nerve terminals in key brain regions.

The findings, published in the journal eBioMedicine, may help explain several of the most common symptoms of long COVID, including chronic fatigue, reduced motivation, slowed movement, memory problems, and the so-called "brain fog."

To examine the brain, researchers used positron emission tomography (PET) to compare people with long COVID to healthy participants. They found a significant reduction in a marker of dopamine system function throughout the major regions of the striatum, a part of the brain involved in regulating motivation, movement, and cognitive processes.

The study also found that changes in specific parts of the striatum were linked to particular symptoms. Reduced dopamine activity in the ventral striatum was associated with loss of motivation, changes in the putamen were linked to slowed movement, and abnormalities in the caudate nucleus were associated with memory impairment.

"Our findings provide strong evidence that long COVID is associated with damage to dopamine-producing neurons," said the study's lead author, Dr. Jeffrey Meyer.

He noted that similar disruptions of the dopamine system have previously been observed in other neurological disorders and may contribute to the development of long COVID symptoms.

The new findings build on the team's earlier research, which showed increased brain inflammation in patients with long COVID, particularly in regions rich in dopaminergic neurons. The current study provides direct evidence that the activity of these neurons is reduced.

According to the researchers, the findings could open new avenues for treatment. The team plans to launch a clinical trial of medications that target the dopamine system to evaluate whether they can improve fatigue, cognitive impairment, memory problems, and reduced motivation in people with long COVID.

The researchers estimate that long COVID affects approximately 5% of the global population and can persist for at least three months after the initial infection. At present, there are no proven treatments that directly address the underlying causes of the condition.

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