Scientists reveal autism has underlying difference in how the brain transmits information

Autism spectrum disorder can present itself with a diverse range of symptoms and a very large scale on degrees of severity. Approaches so far in diagnoses have relied upon analysing the disorder through behaviours, not only through checklists but MRI (magnetic resonance imaging) that maps inputs and responses in the brain.

A mystery has remained on the brain's deeper inner workings behind autism that result in those behavioural observations. A study by researchers at University of Virginia (UVA) have uncovered some intriguing workings of the brain in autism that could help to more accurately recognise autism.

The researchers at UVA’s College and Graduate School of Arts & Sciences have used Diffusion MRI (using molecular diffusion in brain tissue) to expose inner brain mechanisms of autistic and non-autistic people. The method works by measuring how water transmits through the brain and interacts with membranes.

This allowed the team to construct mathematical models of how brain microstructures function, to show underlying structural differences in autistic people compared to those without autism.

“It hasn’t been well understood what those differences might be,” said Benjamin Newman, postdoctoral researcher with UVA’s Department of Psychology. “This new approach looks at the neuronal differences contributing to the etiology of autism spectrum disorder.”

The researchers' work utilises modern day computational techniques based on their foundational understanding of electrochemical conductivity in neurons previously proposed by Andrew Huxley and Alan Hodgkin.

Published by PLOS One, the results correlate well with existing diagnostic methods for autism, such as the Social Communication of the Questionnaire. “What we're seeing 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,” Dr. Newman said. “It's the structure that constrains how the function of the brain works.”

A way to overcome "subjective" observations

This means, that to scientists, autism may not only be seen as an array of behaviours that seem “different”, which can be subjective, and greatly vary person-to-person. Instead, autism could become characterised in more concrete terms through a newly revealed “picture” of its underlying structure in the brain.

Co-author Prof. John Darrell Van Horn, said that: “We need greater fidelity in terms of the physiological metrics that we have so that we can better understand where those behaviours coming from. This is the first time this kind of metric has been applied in a clinical population, and it sheds some interesting light on the origins of ASD.”

Identifying this metric can aid diagnoses and treatments for autistic individuals. But there is still much more to understand about autism, such as additional underlying mechanisms in the brain, but this is a strong step deeper into the autistic brain.

Compared to more traditional research, the study uniquely looks at how the brain transfers information in its dynamic networks. Prof. Van Horn mentioned that this appears to be a successful study in showing there is something fundamental that is different in those diagnosed with autism compared to those who are considered neurotypical.

Reference of the news:

Newman, B.T et al. (2024). Conduction velocity, G-ratio, and extracellular water as microstructural characteristics of autism spectrum disorder. PLOS One.