Altered cortical gyrification, sulcal depth, and fractal dimension in the autism spectrum disorder comorbid attention-deficit/hyperactivity disorder than the autism spectrum disorder.

This brain imaging study looked at structural differences between children with autism plus ADHD versus those with autism alone. Researchers found that children with both conditions had different brain folding patterns in areas involved in social processing, sensory integration, and attention. These brain differences may help explain why some autistic children also have ADHD symptoms and could inform more targeted support strategies.

This neuroimaging study examined brain structure differences between autistic individuals with comorbid ADHD (ASD+ADHD, n=40) and those with autism only (ASD-only, n=74). Using surface-based morphometry analysis of T1-weighted MRI scans from the ABIDE II database, researchers measured cortical complexity through gyrification index, fractal dimension, and sulcal depth. The ASD+ADHD group showed increased fractal dimension in the right fusiform gyrus, greater sulcal depth in bilateral middle temporal gyrus regions, and increased gyrification in the insula/postcentral gyrus compared to ASD-only participants. These findings suggest distinct structural brain differences in individuals with both autism and ADHD compared to autism alone, contributing to understanding of this common comorbidity pattern.

Results suggest ASD+ADHD represents a distinct neurobiological phenotype rather than simple co-occurrence. This may inform diagnostic approaches and highlight the need for tailored interventions addressing both autism and ADHD features in comorbid presentations.

Study used secondary analysis of existing data, cross-sectional design limits causal inferences, relatively small ASD+ADHD sample size (n=40), no information on medication status or symptom severity measures, and findings need replication in independent samples.

Autism spectrum disorder (ASD) frequently occurs accompanied by attention-deficit/hyperactivity disorder (ADHD), which catches increasing attention. The comorbid diagnosis of ASD with ADHD (ASD + ADHD) is permitted in the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-V). However, compared to autism spectrum disorder without other symptoms (ASD-only), the special neural underpinnings in ASD+ADHD remain unclear. Therefore, this study aimed to uncover the differences in cortical complexity between ASD + ADHD and ASD-only patients.

A total of 114 ASD participants (i.e. containing 40 ASD + ADHD and 74 ASD-only participants) with T1-weighted magnetic resonance images were collected from the Autism Brain Imaging Data Exchange II. Afterward, a surface-based morphometry method was carried out to compare the cortical complexity (i.e. gyrification index, fractal dimension, and sulcal depth) between the ASD + ADHD and ASD-only cohorts. Results showed the increased fractal dimension in the right fusiform gyrus of the ASD + ADHD cohort in comparison to the ASD-only cohort. Moreover, the ASD + ADHD cohort exhibited increased sulcal depth in the left middle temporal gyrus/inferior temporal gyrus and right middle temporal gyrus compared to the ASD-only cohort.

Last but not least, the increased gyrification index in the insula/postcentral gyrus was observed in the ASD + ADHD cohort in comparison to the ASD-only cohort. Overall, the present study contributes to the delineation of particular structural abnormalities in ASD + ADHD than ASD-only, enriching the evidence of the combined phenotype of ASD + ADHD.