A study of 166 children suggests that the intensity of autism-related traits may better explain shared brain-network patterns across autism and ADHD than either diagnosis alone.
New research suggests that autism and ADHD may overlap more than their diagnostic labels imply, with the strongest clue lying not in the diagnosis itself but in the intensity of autism-related traits. In a study of 166 verbal children aged six to 12, researchers found that those with more pronounced autism-like characteristics showed stronger links between key brain networks, including the frontoparietal and default mode systems, whether they had autism or ADHD. These networks are involved in social thinking, attention and executive control, pointing to a shared biological thread across some children with either condition.
The findings add to a growing body of work showing that autism and ADHD can share features while remaining distinct diagnoses. A separate mega-analysis published in Nature examined children and adolescents and found that the two conditions were associated with different connectivity patterns overall: autism traits were linked with reduced connectivity in some networks, while ADHD traits were tied to increased connectivity in others. Taken together, the studies suggest that broad diagnostic categories may hide important differences in how individual traits appear in the brain.
The new study also looked at how these connections change as children develop. Normally, links between the frontoparietal and default mode networks become less pronounced with age as the brain grows more specialised. But the researchers found that this pattern of change appeared altered in children with more severe autism-related traits. That may help explain why some children with ADHD show autistic characteristics without meeting criteria for an autism diagnosis.
Beyond brain imaging, the researchers used spatial transcriptomic analysis, a method that compares imaging findings with patterns of gene activity across brain tissue. The regions showing altered connectivity also overlapped with areas where genes involved in brain development are active. Earlier research on autism and ADHD has similarly pointed to distinct neuroanatomical and genetic signatures, suggesting that shared symptoms may emerge through partly overlapping biological pathways rather than a single common cause.
For parents and caregivers, the practical message is that behaviour and development do not always fit neatly into one label. A child with ADHD may also have social or executive-function challenges often associated with autism, and those traits can vary in strength from child to child. The study does not suggest that brain scans can diagnose autism or ADHD, nor does it imply the two conditions are the same. Instead, it strengthens the case for understanding children dimensionally , by looking at the specific traits they show and how intensely they experience them.
Disclaimer: This content is for informational purposes only and is not intended to be a substitute for professional medical judgment, advice, diagnosis, or treatment.
