Exploring the Autistic Brain: A Systematic Review of Diffusion Tensor Imaging Studies on Neural Connectivity in...

Area of Science:

• Neuroimaging
• Neurodevelopmental Disorders
• Autism Spectrum Disorder (ASD)

Background:

• Grey matter has been the primary focus in autism spectrum disorder (ASD) neuroimaging research, particularly in children.
• White matter (WM) alterations may offer a more specific biological signature for ASD neurodiversity.
• Diffusion tensor imaging (DTI) is a key tool for investigating WM in ASD.

Purpose of the Study:

• To systematically review and analyze white matter (WM) changes in adults with autism spectrum disorder (ASD) using Diffusion Tensor Imaging (DTI).
• To compare WM alterations in adult ASD with those observed in pediatric populations.
• To explore the implications of WM changes during brain maturation in ASD.

Main Methods:

• Systematic literature review on PubMed using keywords related to autism and DTI.
• Search conducted on May 21, 2025, yielding 239 results.
• Analysis focused on 26 eligible adult human studies.

Main Results:

• Regionally diverse WM alterations were identified in adult ASD compared to typically developing (TD) individuals.
• Alterations were observed in fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD), axial diffusivity, kurtosis, neurite density, and orientation dispersion index.
• WM changes were less prominent in adults than in children and adolescents, particularly in frontal, interhemispheric, association, and subcortical pathways.

Conclusions:

• White matter alterations in adult ASD are regionally diverse but generally less pronounced than in younger populations.
• This suggests potential improvement or adaptation of brain structure during maturation in individuals with ASD.
• Further research is required to elucidate the neurobiological mechanisms and clinical implications of these findings.