A quarterly publication of the Autism Research Institute

The Autism Research Review International is quarterly publication of the Autism Research Institute

Spring, 2024 | Number 2, Volume 38

Diffusion MRI study reveals differences between brains of individuals with ASD and controls

Researchers in the United States report that by using a technique called diffusion MRI—which measures the movement of water molecules in tissues, helping researchers to see their microarchitecture— they are able to identify structural differences between the brains of individuals with autism spectrum disorders (ASD) and neurotypical controls.

Utilizing this technique, Benjamin Newman and colleagues analyzed scans of 148 adolescents and adults diagnosed with ASD and 124 neurotypical controls. All of the participants were enrolled in the Autism Centers for Excellence Network. “What we’re seeing,” Newman says, “is that there’s a difference in the diameter of the microstructural components in the brains of autistic people that can cause them to conduct electricity slower. It’s the structure that constrains how the function of the brain works.” The researchers also found evidence that the microstructural differences they detected are directly related to participants’ scores on the Social Communication Questionnaire, a clinical tool for diagnosing autism.

Newman and colleagues say their findings suggest that alterations in the structure of axons in the brain and a resulting slowdown in conduction velocity “are widespread throughout the brain and may contribute to the clinical picture of ASD.” In addition, they say their results may help to shed light on recent findings suggesting that ASD involves deficits in long-range connections in the brain and an overreliance on shorter-range or local connections. “If the underconnectivity theory of ASD is accurate,” they say, “it is likely that observed functional connectivity changes have a basis in the cellular microstructure of the neurons.”


“Conduction velocity, G-ratio, and extracellular water as microstructural characteristics of autism spectrum disorder,” Benjamin T. Newman, Zachary Jacokes, Siva Venkadesh, Sara J. Webb, Natalia M. Kleinhans, James C. McPartland, T. Jason Druzgal, Kevin A. Pelphrey, and John Darrell Van Horn, PLOS One, April 17, 2024 (free online). Address: John Darrell Van Horn, jdv7g@ virginia.edu.


“Study identifies new metric for diagnosing autism,” Russ Bahorsky, news release, University of Virginia, April 17, 2024.