Dopamine May Play a Bigger Role in Autism Than We Thought

Understanding autism in the brain requires looking beyond outward behavior to the chemical signals firing beneath the surface.

Researchers at the University of Southern Denmark and Odense University Hospital combined three advanced brain scanning techniques to study 60 adults. Their findings revealed that autistic individuals exhibit higher dopamine D2 receptor levels and elevated glucose energy consumption in deep brain regions, which alter how these structures communicate with the rest of the brain.

The role of dopamine in autism

Autism affects ~2% of adults, and yet there is still a lack of knowledge behind the biological mechanisms that drive the condition. Doctors still rely entirely on behavioral observations to make a diagnosis, and the few medications approved for autism only target secondary symptoms, rather than core traits like social communication differences.

Early laboratory models have suggested that dopamine, a chemical messenger for motivation and movement, might work differently in autism; however, human brain imaging studies have produced conflicting results—and almost all studies focused exclusively on male participants.

One possible explanation for these inconsistencies may be that the previous studies tended to examine brain features in isolation. Some examined neurotransmitters, others measured energy consumption, and some tracked neural connectivity—but nobody had looked at how these systems may interact within the same living brain.

“Our study is the first to investigate the neurotransmitter dopamine and communication between brain regions in the same study. This gives us a more nuanced understanding of the neurobiological mechanisms associated with autism,” said lead author Dr. Laust Vind Knudsen, a postdoctoral researcher at Odense University Hospital and the University of Southern Denmark.

Knudsen and the team measured dopamine D2 receptors, glucose metabolism, and functional brain connectivity simultaneously to understand how these biological features interact in the brains of autistic adults.

Key findings on brain energy and dopamine in autism

The team recruited 60 adult participants: 30 autistic individuals and 30 neurotypical controls, and matched participants by age, body mass index, and IQ, while keeping an equal ratio of men and women. Using simultaneous dual-tracer positron emission tomography and functional magnetic resonance imaging, they tracked dopamine D2 receptor availability, recorded cellular glucose metabolism, and mapped real-time brain connectivity.

Autistic participants showed a higher concentration of dopamine D2 receptors, particularly within the thalamus. When examining sex differences, autistic men showed elevated receptor levels across several subcortical regions—including the nucleus accumbens and putamen—while autistic women showed noticeable thalamic increases compared to neurotypical women.

Autistic adults also consumed significantly more glucose energy in the thalamus and globus pallidus, with higher metabolic rates correlating directly with greater social and communication differences.

While dopamine receptor availability and energy use rose together across all participants, dopamine altered brain communication differently in autism. Higher receptor availability in autistic participants corresponded to reduced functional connectivity between deep brain regions and the outer cortex.

“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.

Clinical implications and future research in autism

The study findings provide a clearer biological framework for understanding autism. Exploring these linked mechanisms could help researchers develop objective biological markers and target core autistic traits, rather than just managing secondary symptoms.

The findings also offer fresh insight into co-occurring conditions; since dopamine drives attention and reward pathways, shared biological mechanisms could explain why many autistic individuals also have attention deficit hyperactivity disorder (ADHD).

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Revealing distinct patterns of dopamine-driven connectivity between autistic men and women also demonstrates that future neuroimaging studies and clinical trials must account for sex differences.

However, the researchers do acknowledge several limitations on this work. The study only evaluated a small sample of 60 cognitively able adults without major co-occurring conditions, meaning the results may not apply to children, non-verbal individuals, or those with intellectual disabilities. Behavioral traits were also measured using self-reported questionnaires rather than standardized clinical observations.

Looking ahead, the team plans to test these findings in larger, more diverse cohorts.

“Our findings also raise new questions about why autism and ADHD so often occur together, which we would like to investigate further,” said Knudsen.

“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,” Knudsen added.

Reference: Knudsen LV, Vafaee MS, Farahani ZA, Sheldrick-Michel AJ, Michel TM. Subcortical dopamine D2 receptor availability and glucose metabolism in autism: a dual-tracer PET/MR study. Eur J Nucl Med Mol Imaging. 2026. doi: 10.1007/s00259-026-08053-4

Original story: University of Southern Denmark