By analyzing three different types of brain scans, researchers uncovered new clues about the biological processes linked to autism. The results point to the dopamine system as a potentially important part of autism biology.
Autism is associated with differences across several systems in the brain, but understanding how those differences connect has been difficult. Researchers from the University of Southern Denmark and Odense University Hospital investigated that question in 60 adults using three forms of brain imaging.
For the first time, the researchers combined three advanced brain scanning techniques to examine the dopamine system, energy use, and communication among brain regions within the same study.
The results provide a more detailed view of biological mechanisms associated with autism. Autistic participants had more dopamine D2 receptors than neurotypical participants, suggesting that the dopamine system may be an important part of autism biology.
Three scans reveal a dopamine difference
Earlier autism research has largely examined communication among different parts of the brain, while fewer studies have focused on neurotransmitters or the way the brain uses energy.
Neurotransmitters are chemical messengers that help regulate communication throughout the brain. Examining whether these signals differ is therefore important for understanding why communication between certain brain regions may vary between autistic and neurotypical people.
By studying these processes together, the researchers could identify relationships that had not previously been described.
“Our study is the first to investigate the neurotransmitter dopamine, the brain’s energy use (glucose metabolism) and communication between brain regions in the same study. This gives us a more nuanced understanding of the neurobiological mechanisms associated with autism,” says Laust Vind Knudsen, postdoc at the Research Unit for Psychiatry, Odense University Hospital and the University of Southern Denmark.
Knudsen is the study’s first author. The researchers found, among other results, that certain deep brain regions in autistic participants showed both greater energy use and more dopamine receptors than those same regions in neurotypical participants.
The research was conducted as part of Knudsen’s PhD project at the University of Southern Denmark and Odense University Hospital. Professor Tanja Maria Sheldrick Michel served as research leader and principal supervisor, while Professor Manouchehr Seyedi Vafaee was co-supervisor.
Dopamine differences tracked brain energy use
Dopamine is a neurotransmitter that some nerve cells use to communicate with one another. It contributes to functions including motivation, learning, and movement.
Among the autistic participants, a greater number of dopamine receptors was associated with higher energy use in the same areas of the brain.
The researchers also found that the relationship between the dopamine system and communication among brain regions differed between autistic and neurotypical participants.
“Our findings suggest that the dopamine system not only differs between autistic and neurotypical people. They also indicate that the dopamine system affects communication between brain regions differently in the two groups. This suggests that the dopamine system may play a more fundamental role in autism than previously thought,” says Laust Vind Knudsen.
The results raise autism ADHD questions
The researchers emphasize that the findings do not explain why autism develops and cannot be used to diagnose it. Instead, the study provides new information about biological variation and mechanisms associated with autism, including how neurotransmitters, energy use, and communication among brain regions may interact.
The findings are also relevant to questions about ADHD because many autistic people are also diagnosed with ADHD, and dopamine plays an important role in that condition.
This raises the possibility that some dopamine-related biological mechanisms could be shared between autism and ADHD, potentially helping researchers investigate why ADHD occurs so frequently among autistic people.
“Brain research can help us understand autism better, not in order to change autistic people, but to create greater understanding of neurodiversity and better conditions in society. Our findings also raise new questions about why autism and ADHD so often occur together, which we would like to investigate further,” says Laust Vind Knudsen.
Larger studies still need confirmation
The study involved 60 adults and is the first positron emission tomography (PET) study specifically designed to also investigate possible differences between autistic men and women.
The researchers caution that larger studies are still needed to determine whether the results can be confirmed and reproduced in other groups of autistic people.
Reference: “Subcortical dopamine D2 receptor availability and glucose metabolism in autism: a dual-tracer PET/MR study” by Laust Vind Knudsen, Manouchehr Seyedi Vafaee, Ziba Ahangarani Farahani, Abigail Jane Sheldrick-Michel and Tanja Maria Michel, 6 July 2026, European Journal of Nuclear Medicine and Molecular Imaging.
DOI: 10.1007/s00259-026-08053-4
Funding: The Psychiatry Research Fund, Region of Southern Denmark.
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