Have you ever heard of the saying ‘the eyes tell all’? Well, now they may also be true about neurodevelopmental conditions. New research from Flinders University and the University of South Australia and published in the Frontiers in Neuroscience reveal that eye recordings could identify distinct signals for Attention Deficit Hyperactivity Disorder (ADHD) and Autism Spectrum Disorder (ASD). These signals could provide potential biomarkers for the condition.
ADHD and ASD are both neurodevelopmental conditions that have a global prevalence of 3.4% and 1%, respectively. Also, one in three children with ASD also meets the diagnostic behavior for ADHD.
ADHD is characterized by difficulty managing impulsive behaviors, being overactive, and a struggle to pay attention. While, ASD is where people interact, behave, communicate and learn in different ways. Both conditions are commonly diagnosed in childhood, but due to their similar traits, sometimes diagnoses can take a long time. Research into different and new diagnostic tools will be beneficial to all with the conditions.
An electroretinogram (ERG) was used in this study and a discrete wavelet transform (DWT) analysis was applied to the data. ERG is a diagnostic test that measures the electrical responses of different cells in the retina in response to a light stimulus. This study took 55 people with ASD, 15 with ADHD, and 156 control individuals.
The researchers found that the children with less ERG energy had ASD and children with higher energy had ADHD.
“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.” Says Dr Paul Constable, lead author of the study.
“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.”
“Ultimately, we’re looking at how the eyes can help us understand the brain,” Says Fernando Marmolejo-Ramos, co-researcher on the paper. “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.
“It is truly a case of watching this space; as it happens, the eyes could reveal all.”
This approach may also be useful in the future for schizophrenia and bipolar disorder.