New brain-imaging research suggests that changes in the dopamine system may be associated with Long COVID brain fog, fatigue, memory difficulties, and loss of motivation.

Long COVID can involve persistent brain fog and fatigue long after the initial infection. New PET imaging research is providing a closer look at one possible biological factor: changes within the brain's dopamine system.

Researchers have identified abnormalities involving dopamine-related nerve terminals in people with Long COVID, raising new questions about how dopamine signaling may relate to cognitive and physical symptoms.

What Does Dopamine Have to Do With Long COVID?

Dopamine is a neurotransmitter involved in much more than pleasure and reward. It plays important roles in motivation, movement, attention, learning, memory, and goal-directed behavior.

Because many of these functions overlap with symptoms reported in Long COVID, researchers have begun examining whether changes in dopamine signaling could help explain certain aspects of the condition.

KEY FINDING

Brain imaging identified lower levels of a marker associated with dopamine-releasing nerve terminals in people with Long COVID. The differences were also associated with symptoms involving motivation, movement, and memory.

Brain Scans Show Changes in the Dopamine System

Researchers at the Centre for Addiction and Mental Health (CAMH) used positron emission tomography (PET) to examine the brains of people with Long COVID.

The study measured a biological marker associated with dopamine-releasing nerve terminals.

Compared with healthy participants, people with Long COVID had substantially lower levels of this marker across major areas of the striatum, a group of brain regions involved in movement, motivation, learning, and cognition.

The researchers reported that these lower levels may indicate a reduced density of dopamine nerve terminals.

Importantly, the study demonstrates an association. It does not establish that altered dopamine function causes Long COVID or its symptoms.

Could Dopamine Changes Help Explain Long COVID Brain Fog?

One of the more notable findings was that differences in specific areas of the dopamine system were associated with different symptoms.

Lower dopamine-related marker levels in the ventral striatum were associated with greater loss of motivation. Changes in the dorsal putamen were associated with slower movement, while reductions involving the caudate putamen were associated with memory difficulties.

These findings provide a possible biological pathway researchers can investigate when studying symptoms commonly described as Long COVID brain fog.

WHY THIS MATTERS

Long COVID brain fog can involve difficulty concentrating, slower thinking, memory problems, and mental fatigue. This research suggests that some of these symptoms may be associated with measurable differences in brain systems involved in cognition, motivation, and movement.

Brain Inflammation May Also Play a Role

The findings build on earlier research from the same team that identified elevated brain inflammation in people with Long COVID.

That inflammation appeared particularly prominent in areas containing large numbers of dopamine-releasing neurons.

Because inflammation can affect neuronal function, researchers are investigating whether persistent neuroinflammation could contribute to the dopamine-system abnormalities identified in the newer study.

Taken together, the research raises an important question: Could inflammation and altered dopamine signaling be connected in some people with Long COVID?

At this point, that relationship remains under investigation.

Why Dopamine Matters for Motivation, Focus and Cognitive Function

Although dopamine is frequently described as the brain's "reward chemical," its biological role is considerably broader.

Healthy dopamine signaling contributes to:

• Motivation and goal-directed behavior
• Attention and cognitive function
• Learning and memory
• Movement and motor control
• Reward processing

Changes within these pathways could therefore be relevant to the combination of cognitive and physical symptoms researchers are observing in Long COVID.

This doesn't mean that every case of fatigue, poor concentration, or low motivation is caused by dopamine dysfunction. Long COVID is a complex condition that likely involves multiple biological mechanisms.

Is Dopamine a Potential Research Target for Long COVID?

The findings may influence how scientists investigate future Long COVID treatments.

Much of the research into Long COVID has focused on inflammation, immune-system abnormalities, and other potential biological mechanisms. This study suggests that researchers may also want to investigate the dopamine system.

Investigators are planning clinical research examining whether modifying dopamine function affects symptoms such as memory problems, fatigue, and loss of motivation.

However, this is an important distinction: dopamine-targeting therapies have not been established as treatments for Long COVID.

Any medications or other interventions designed to alter dopamine function would need to be evaluated in controlled clinical trials for their safety and effectiveness in people with Long COVID.

CLINICAL PERSPECTIVE

This research does not establish dopamine-enhancing medications, supplements, or other interventions as treatments for Long COVID. Instead, it identifies a biological pathway that researchers can investigate further in controlled studies.

What This Long COVID Study Means

Long COVID remains complex, and dopamine dysfunction is unlikely to explain every symptom or every case.

What makes this research noteworthy is the identification of measurable differences in a brain system involved in several functions commonly affected in Long COVID—including memory, motivation, cognition, and movement.

The study also adds to growing research examining potential biological mechanisms behind persistent neurological symptoms following COVID-19.

Further research will be necessary to determine what causes these dopamine-system changes, whether they are reversible, and whether targeting this pathway can meaningfully improve symptoms.

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Frequently Asked Questions

Can low dopamine cause Long COVID brain fog?
The current research does not establish that low dopamine causes Long COVID brain fog. Researchers found dopamine-system differences that were associated with certain symptoms, but additional studies are needed to establish causation.

Does Long COVID affect dopamine?
Recent PET imaging research has identified abnormalities in a marker associated with dopamine-releasing nerve terminals in people with Long COVID. Researchers are still determining what causes these changes and what they mean clinically.

Can increasing dopamine treat Long COVID fatigue?
There is currently insufficient evidence to conclude that increasing dopamine treats Long COVID fatigue. Researchers are investigating the dopamine system as a potential therapeutic target, but controlled clinical trials are needed.

Why is dopamine important for the brain?
Dopamine is involved in motivation, movement, attention, learning, memory, reward processing, and goal-directed behavior.

References

Brain scans reveal a possible cause of long COVID fatigue and brain fog
Science News
September 21, 2026
Centre for Addiction and Mental Health

Loss of vesicular monoamine transporter 2 in striatum long COVID and relationship to neuropsychiatric symptoms
eBioMedicine
August 2026
Yuhan Karina Liu et al.

Medical Disclaimer: This article is for informational and educational purposes only and is not medical advice. Consult a qualified healthcare professional regarding medical conditions, symptoms, diagnosis, or treatment.

† These statements have not been evaluated by the Food and Drug Administration. These statements are not intended to diagnose, treat, cure, or prevent disease.