Researchers from the University of Southern Denmark and Odense University Hospital have taken a fresh look at what autism looks like inside the brain, and their findings suggest that a brain chemical called dopamine may play a bigger role than previously thought.
The study, published in the journal European Journal of Nuclear Medicine and Molecular Imaging, combined three advanced brain-scanning techniques together for the first time to examine 60 adults. This gave the team a much fuller picture of what’s happening across different parts of the brain in autistic and neurotypical people.
Three Scans, One Bigger Picture
Until now, most research into the autistic brain has focused on how different regions communicate with each other. Fewer studies have looked at brain chemistry (the neurotransmitters that carry messages between nerve cells) or at how the brain uses energy.
The Danish team combined all three approaches. They used two PET scans and a functional MRI scan to examine the dopamine system, energy use, and communication between brain regions at the same time.
“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,” said Laust Vind Knudsen, postdoc at the Research Unit for Psychiatry, Odense University Hospital and the University of Southern Denmark, and first author of the study.
What They Found
The scans revealed that autistic participants had more of a type of dopamine receiver called the D2 receptor than the neurotypical participants did. In certain deep regions of the brain, this went hand in hand with higher energy use.
Dopamine is a well-known brain chemical involved in motivation, learning, movement, and reward. For it to do its job, it has to attach to receivers on nerve cells called receptors. The D2 receptor is one of the most important, and it has already been linked to ADHD and other conditions.
The researchers also found that dopamine seemed to influence communication between brain regions differently in autistic people compared with neurotypical people.
“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,” said Knudsen.
What This Does (and Doesn’t) Mean
The researchers are clear about the limits of the study. It doesn’t explain why autism develops, and it cannot be used to diagnose anyone. What it does offer is a better understanding of the biological variation that exists in autism and how different brain systems interact.
The findings also raise interesting questions about the overlap between autism and ADHD. Around 40% of autistic people also have an ADHD diagnosis, and dopamine plays a central role in ADHD. If autism and ADHD share some of the same dopamine-related biology, that could help explain why the two so often go together.
Interestingly, the only medications approved in the US that are used to help autistic children with aggression and irritability also work by affecting the D2 receptor. That’s part of the reason the team wanted to look at this particular receptor in the first place.
Understanding, Not Changing
Knudsen is careful to frame the research within a wider conversation about neurodiversity.
“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,” he said.
The study is the first PET-based investigation specifically designed to look at possible differences between autistic men and women, and the team stresses that larger studies are needed to confirm and extend the findings.
Still, by looking at brain chemistry, energy use and communication in one go, the research offers a more joined-up view of the autistic brain than has been possible before, and points to dopamine as an area worth much closer study.
Knudsen, L.V., Seyedi Vafaee, M., Ahangarani Farahani, Z., Sheldrick-Michel, A.J., & Michel, T.M. Subcortical dopamine D2 receptor availability and glucose metabolism in autism: a dual-tracer PET/MR study. European Journal of Nuclear Medicine and Molecular Imaging (2026). DOI: 10.1007/s00259-026-08053-4