Research published in molecular psychiatry Our findings suggest that autism and ADHD may be related at a biological level that goes beyond traditional diagnostic labels. Although it is well known that these two conditions often occur together, their common underlying mechanisms remain unclear.
Researchers at the Child Mind Institute and partner institutions have found that the severity of autism-related symptoms, rather than whether a child is formally diagnosed with autism or ADHD, is associated with specific patterns of brain connectivity and gene activity. These patterns emerged in children diagnosed with autism spectrum disorder (ASD) or attention-deficit/hyperactivity disorder (ADHD). This discovery further accelerates a shift in research focused on understanding neurodevelopmental conditions along a spectrum rather than as discrete categories.
Brain connectivity patterns associated with autistic traits
The study was led by Adriana Di Martino, MD, founding director and senior researcher at the Child Mind Institute Autism Center. The researchers used resting-state functional MRI to analyze brain connectivity in 166 verbal children aged 6 to 12 who had been diagnosed with autism or ADHD (but not autism).
Children with more pronounced autism symptoms showed stronger connections between major brain networks, including the frontoparietal (FP) and default mode (DM) systems. These networks play important roles in social thinking and executive function.
During normal development, connections between these networks tend to decrease over time, allowing the brain to specialize. However, the study points out that this reduction may not occur in the same way in children with more severe autism traits, as their brains mature differently. Remarkably, these patterns were seen regardless of whether the child was diagnosed with autism or ADHD.
Genetic signals shared across conditions
The researchers also found that these brain connectivity patterns matched regions of gene expression associated with neural development. Many of these genes have previously been associated with both autism and ADHD. This overlap suggests that similar biological processes may contribute to the traits seen across both conditions.
“In our clinic, we have observed that some children with ADHD share symptoms qualitatively similar to those observed in autism, even if they do not fully meet the diagnostic criteria for ASD,” says Dr. Adriana Di Martino. “By focusing on common brain gene expression patterns associated with autism symptoms across both ASD and ADHD, we are able to point to a common biological basis for these clinical observations. Our findings provide a more nuanced and dimensional understanding of the neurodevelopmental state.”
Advanced techniques reveal overlap between brain and genes
To uncover these connections, the team used advanced brain imaging and in silico Spatial transcriptome analysis — a computational technique that compares brain connectivity data with maps of gene activity throughout the brain. This method allowed researchers to directly link patterns of neurotransmission to underlying gene expression.
Such an approach could help identify biological markers or biomarkers that will improve how these conditions are recognized and studied in the future.
Key findings from the research
- Autism symptom severity is associated with similar brain connectivity patterns in children with ASD and some children with ADHD who are not diagnosed with autism
- Differences in connectivity correspond to regions where genes involved in brain development are active
- Common clinical features of autism and ADHD are associated with overlapping genetic mechanisms
- Brain network maturation processes may play an important role in the development of autism-related symptoms in both groups
- This finding supports the use of both dimensional and categorical models to understand neurodevelopmental states
- This study may inform future efforts to identify biomarkers and better understand vulnerability to autistic traits.
Implications for diagnosis and treatment
These findings highlight the value of focusing on specific symptoms and their biological basis, rather than relying solely on diagnostic categories. This approach could lead to more individualized strategies to identify and treat neurodevelopmental conditions based on each individual’s brain profile.
This study also supports a broader shift in psychiatry to a dimensional, data-driven framework that cuts across traditional diagnoses. Initiatives such as the Child Mind Institute’s Healthy Brain Network reflect this direction by providing large-scale brain imaging and behavioral data along with free diagnostic assessments for families.
Together, these efforts could reshape the way we understand autism and ADHD and help move toward a more accurate and biologically informed model of care.
