Researchers from the Child Mind Institute and partner institutions found that the severity of autism-related symptoms, rather than whether a child is formally diagnosed with autism or ADHD, is linked to specific patterns of brain connectivity and gene activity. These patterns appeared in children diagnosed with either autism spectrum disorder (ASD) or attention-deficit/hyperactivity disorder (ADHD). The findings add to a growing shift in research that focuses on understanding neurodevelopmental conditions along a spectrum rather than as separate categories.

Brain Connectivity Patterns Linked to Autism Traits

The study was led by Adriana Di Martino, MD, Founding Director of the Autism Center at the Child Mind Institute and Senior Research Scientist. The team analyzed brain connectivity using resting-state functional MRI in 166 verbal children ages 6-12 diagnosed with autism or ADHD (without autism).

Children with more pronounced autism symptoms showed stronger connections between key brain networks, including the frontoparietal (FP) and default-mode (DM) systems. These networks play an important role in social thinking and executive function.

In typical development, connections between these networks tend to decrease over time, allowing the brain to specialize. However, the study found that this reduction may not occur in the same way in children with more severe autism traits, pointing to differences in how the brain matures. Notably, these patterns were seen regardless of whether a child had an autism or ADHD diagnosis.

Shared Genetic Signals Across Conditions

The researchers also found that these brain connectivity patterns align with regions of gene expression linked to 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 traits seen across both conditions.

“We see in the clinic 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 shared brain-gene expression patterns linked to autism symptoms across both ASD and ADHD, we can point towards a shared biological basis of these clinical observations. Our findings provide a more nuanced, dimensional understanding of neurodevelopmental conditions.”

Advanced Methods Reveal Brain and Gene Overlap

To uncover these connections, the team used an integrative approach that combined advanced brain imaging with in silico spatial transcriptomic analysis — a computational technique that compares brain connectivity data with maps of gene activity across the brain. This method allowed researchers to directly link patterns of neural communication with underlying genetic expression.

Such approaches could help identify biological markers, or biomarkers, that improve how these conditions are recognized and studied in the future.

Key Findings From the Study

• Autism symptom severity is linked to similar brain connectivity patterns in children with ASD and in some children with ADHD who do not have an autism diagnosis
• Differences in connectivity correspond with regions where genes involved in brain development are active
• Shared clinical traits between autism and ADHD are associated with overlapping genetic mechanisms
• Brain network maturation processes may play a key role in the development of autism-related symptoms in both groups
• The findings support using both dimensional and categorical models to understand neurodevelopmental conditions
• The research may guide future efforts to identify biomarkers and better understand vulnerability to autism traits

Implications for Diagnosis and Treatment

These findings highlight the value of focusing on specific symptoms and their biological basis rather than relying only on diagnostic categories. This approach could lead to more personalized strategies for identifying and treating neurodevelopmental conditions based on each individual’s brain profile.

The study also supports a broader shift in psychiatry toward dimensional and data-driven frameworks that cut 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 evaluations for families.

Together, these efforts may help reshape how autism and ADHD are understood, moving toward a more precise and biologically informed model of care.