Electrical activity of the retina in response to a light stimulus could signal common neurodevelopmental disorders, according to new research from Flinders University and the University of South Australia.
In the first study of its kind, researchers found that recordings from the retina could identify distinct signals for both Attention Deficit Hyperactivity Disorder (ADHD) and Autism Spectrum Disorder (ASD) providing a potential biomarker for each condition.
Using an electroretinogram (ERG) – a diagnostic test that measures the electrical activity of the retina in response to a light stimulus – researchers found that children with ADHD showed higher overall ERG energy, whereas children with ASD showed less ERG energy.
Research optometrist at Flinders University, Dr Paul Constable, said the preliminary findings indicate promising results for improved diagnoses and treatments in the future.
“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,” Constable said.
“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 hopes their research can demonstrate distinct differences between ADHD and ASD.
“Retinal signals have specific nerves that generate them, so if we can identify these differences and localise 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,” Constable said.
“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.”
According to the World Health Organization, one in 100 children has ASD, with 5-8% of children diagnosed with ADHD.
ADHD is a neurodevelopmental condition characterised by being overly active, struggling to pay attention, and difficulty controlling impulsive behaviours. ASD is also a neurodevelopmental condition where children behave, communicate, interact, and learn in ways that are different from most other people.
Co-researcher and expert in human and artificial cognition at the University of South Australia, Dr Fernando Marmolejo-Ramos, said the research has potential to extend across other neurological conditions.
“Ultimately, we’re looking at how the eyes can help us understand the brain,” Marmolejo-Ramos said.
“While further research is needed to establish abnormalities in retinal signals that are specific to these and other neurodevelopmental disorders, what we’ve observed so far shows that we are on the precipice of something amazing,” he said.
This research was conducted in partnership with McGill University, University College London and the Great Ormond Street Hospital for Children.