Early diagnosis of neurodevelopmental conditions, such as Attention Deficit Hyperactivity Disorder (ADHD) and Autism Spectrum Disorder (ASD), is critical for treatment and symptom management processes.
Now, a team of researchers from the University of South Australia has found that recordings from the retina may be used to distinguish unique signals for both ADHD and ASD, offering a possible biomarker for each disorder. According to a press release published by the institution, The team used the "electroretinogram" (ERG), a diagnostic test that measures the electrical activity of the retina in response to light, and found out that children with ASD showed less ERG energy while children with ADHD displayed more ERG energy.
Promising results for improved diagnosis and treatments
Dr. Paul Constable, a research optometrist at Flinders University, stated in the press release that the early results are promising for future advancements in diagnostics and treatments.
“ASD and ADHD are the most common neurodevelopmental disorders diagnosed in childhood. But as they often share similar traits, making diagnoses for both conditions can be lengthy and complicated,” said Dr. Constable. "Our research aims to improve this. By exploring how signals in the retina react to light stimuli, we hope to develop more accurate and earlier diagnoses for different neurodevelopmental conditions," he added.
ERG, as a standard test model, has already been in use since the 1940s to identify retinal disorders. Still, its use for neurodevelopmental conditions both makes it possible to separate ADHD and autism cases from control cases and clearly distinguishes between the two conditions.
Significant differences between ASD and ADHD patients
The research included 226 young people, 55 ADS-diagnosed subjects, 15 ADHD-diagnosed subjects, and 156 control individuals aged between 3 and 27 and examined them through an ERG test. B-wave energy levels and oscillatory potentials demonstrated significant differences between ASD patients, ADHD patients, and control subjects. While ADHD patients exhibited high overall ERG energy levels than control patients, ASD patients showed lower overall ERG energy levels.
“Retinal signals have specific nerves that generate them, so if we can identify these differences and localize them to specific pathways that use different chemical signals that are also used in the brain, then we can show distinct differences for children with ADHD and ASD and potentially other neurodevelopmental conditions," stated Constable in the press release.
"This study delivers preliminary evidence for neurophysiological changes that not only differentiate both ADHD and ASD from typically developing children, but also evidence that they can be distinguished from each other based on ERG characteristics.”
The research team aims to expand their trials across other neurological conditions. Dr. Fernando Marmolejo-Ramos, a co-researcher and expert in human and artificial cognition at the University of South Australia, said, “Ultimately, we’re looking at how the eyes can help us understand the brain.”
The results of the study were published in the journal Frontiers in Neuroscience.