Has Your Memory Weakened After COVID?

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A question many have raised during the pandemic: a person may recover from fever and cough, only to discover that something else has not fully healed: they enter a room and forget why they entered it, reread the same page, or search for a word that used to come to mind easily.

Many refer to this as 'brain fog' after COVID, and now a Canadian study offers a potential biological explanation for some of these complaints, particularly memory impairment and slow thinking. The study, published by Liu and colleagues in 2026 in the journal eBioMedicine, used positron emission tomography (PET) to examine 24 individuals suffering from long COVID and compared them to 24 healthy individuals of similar ages. They focused on a protein called VMAT2, which is abundant in the nerve endings that release dopamine within the 'striatum' area of the brain. This area is involved in movement, motivation, and some functions of learning and memory.

The researchers found that the protein signal was lower in the long COVID group in the areas they examined. Most intriguingly, the difference in signal location was accompanied by a difference in symptoms: a decrease in one area was associated with reduced motivation and apathy, while in another it was linked to slowed movement, and a decrease in a third area was associated with complaints of memory decline.

Thus, the study opens a window to understanding an experience that patients have described for years: I appear healthy, but my mind no longer works as it used to. However, the results should be read carefully.

The PET image measures the association of the imaging substance with the VMAT2 protein; it does not directly show dead neurons, nor does it prove that COVID alone caused this change or that it is permanent. Additionally, the number of participants is small, and the relationship of the indicator to memory is an exploratory result that needs confirmation in larger studies that follow patients over time and compare their images before and after the disease.

The result does not mean that every instance of forgetfulness after COVID is caused by a dopamine deficiency; sleep disorders, fatigue, depression, and other medical reasons may also affect concentration.

The value of the research is that it moves the question a step forward: what might be happening inside the brain when symptoms persist after the infection has resolved? If the role of this neural pathway is confirmed, it may help in testing targeted treatments in the future.

As of now, there is no evidence in this study that drugs that increase dopamine restore memory.

The most important message to the patient is simple: your complaints deserve to be listened to and evaluated, and science is beginning to find measurable effects for them.