Understanding the Overlap Between Autism and ADHD

For decades, autism and ADHD were considered separate diagnoses, rarely given together. However, a growing body of research shows these neurodevelopmental conditions frequently overlap — with significant implications for diagnosis, support, and understanding neurodivergence.

High Rates of Co-Occurrence

Studies estimate that 40-70% of autistic people also meet the criteria for ADHD, while 20-50% of people with ADHD show autistic traits, according to a 2023 review in eNeuro. This bidirectional overlap suggests shared biological roots, though the conditions present differently in behavior and cognition.

The DSM-5 (the diagnostic manual used by clinicians) began allowing dual diagnoses of autism and ADHD in 2013.

The DSM-5 (the diagnostic manual used by clinicians) began allowing dual diagnoses of autism and ADHD in 2013. Before that, many individuals — particularly adults and girls — were misdiagnosed or missed entirely, as noted by Vanderbilt University researchers in their analysis of diagnostic trends.

Unique Brain Patterns

Neuroimaging studies reveal that co-occurring autism and ADHD involve distinct brain dynamics. A 2024 study in ScienceDirect found differences in brain networks responsible for attention and flexible thinking in people with both conditions compared to those with either autism or ADHD alone. These findings suggest that the interaction of autism and ADHD traits may lead to unique cognitive profiles.

Clinical and Lived Realities

People with both conditions often face greater support needs, including higher rates of anxiety, learning differences, and sensory processing challenges, as highlighted by a CDC-supported study. Yet diagnostic delays are common: Many adults report being treated for one condition while their other traits were overlooked.

'Integrated assessments are crucial,' says a 2023 PMC paper, noting that autism’s social communication traits and ADHD’s attention regulation differences interact in ways that require tailored approaches.

Moving Forward

While 'AuDHD' isn’t yet a formal diagnosis, its recognition is improving care. Researchers caution, however, against overgeneralizing traits or framing co-occurrence as an advantage without evidence — a trend seen in some media coverage.