Summary: Measuring the electrical activity of the retina in response to the light stimulus could be a biomarker for ADHD and autism, the researchers report.
Source: University of South Australia
It is often said that “the eyes say it all,” but regardless of their outward expression, according to new research from Flinders University and the University of South Australia, the eyes may also be able to signal neurodevelopmental disorders such as ASD and ADHD.
In the first study of its kind, the 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 the “electroretinogram” (ERG) – a diagnostic test that measures the electrical activity of the retina in response to a light stimulus – the researchers found that children with ADHD exhibited higher overall ERG energy, while children with ASDs showed less ERG energy.
Flinders University optometrist Dr. Paul Constable says the preliminary results point to promising results for better diagnosis and treatment in the future.
“ASD and ADHD are the most common neurodevelopmental disorders diagnosed in childhood. But because they often share similar traits, diagnosing both conditions can be time-consuming and complicated,” says 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 various neurodevelopmental conditions.
“Retinal signals have specific nerves that generate them, so if we can identify these differences and locate them in 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 conditions. of neurodevelopment “.
“This study provides 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 have ASD, with 5-8% of children diagnosed with ADHD.
Attention Deficit Hyperactivity Disorder (ADHD) is a neurodevelopmental condition characterized by being overly active, having a hard time paying attention, and having difficulty controlling impulsive behaviors. Autism Spectrum Disorder (ASD) is also a neurodevelopmental condition in which children behave, communicate, interact and learn in different ways than most other people.
Dr Fernando Marmolejo-Ramos, a co-researcher and expert in human and artificial cognition at the University of South Australia, says the research has the potential to extend to other neurological conditions.
“Ultimately, we’re looking at how the eyes can help us understand the brain,” says Dr. Marmolejo-Ramos.
“While more research is needed to establish abnormalities in retinal signals that are specific to these and other neurodevelopmental disorders, what we have observed so far shows that we are on the verge of something surprising.
“It really is a case of looking at this space; by chance, the eyes could reveal everything.
This research was conducted in collaboration with McGill University, University College London and Great Ormond Street Hospital for Children.
About this ADHD and ASD research news
Author: Annabel Mansfield
Source: University of South Australia
Contact: Annabel Mansfield – University of South Australia
Image: The image is in the public domain
Original research: Free access.
“Discrete Wavelet Transformation Analysis of the Electroretinogram in Autism Spectrum Disorder and Attention Deficit Hyperactivity Disorder” by Fernando Marmolejo-Ramos et al. Frontiers in neuroscience
Discrete Wavelet Transformation Analysis of the Electroretinogram in Autism Spectrum Disorder and Attention Deficit Hyperactivity Disorder
Background: To evaluate the electroretinogram waveform in autism spectrum disorder (ASD) and attention deficit hyperactivity disorder (ADHD) using a discrete wavelet transform (DWT) approach.
Methods: A total of 55 ASD, 15 ADHD, and 156 control subjects took part in this study. Light-adapted full-field electroretinograms (ERGs) were recorded using a Troland protocol, taking pupil size into account, with five flash intensities ranging from –0.12 to 1.20 log fotopic cd.sm-2. A DWT analysis was performed using the Haar wavelet on the waveforms to examine the energy within the time windows of the waves a and b and the oscillatory potentials (OPs) which produced six DWT coefficients related to these parameters. The central frequency bands were between 20 and 160 Hz relative to wave a, wave b and the OP represented by the coefficients: a20, a40, b20, b40, op80 and op160, respectively. Furthermore, the wave amplitude b and the percentage energy contribution of the OPs (% OPs) in the total ERG broadband energy was evaluated.
Results: There were significant group differences (p <0.001) in the coefficients corresponding to the energies in wave b (b20, b40) and OP (op80 and op160) as well as in the amplitude of wave b. Notable differences between the ADHD and control groups were found in the b20 and b40 coefficients. Conversely, the greatest differences between the ASD and the control group were found in the coefficients op80 and op160. The amplitude of the b wave showed significant differences in both ASD and ADHD groups compared to control participants, for flash intensities greater than 0.4 log fotopic cd.sm-2 (p <0.001).
Conclusion: This methodological approach can provide insights into neuronal activity in studies investigating group differences in which retinal signaling can be altered through neurodevelopmental or neurodegenerative conditions. However, further work will be needed to determine whether retinal signal analysis can offer a classification model for neurodevelopmental conditions in which there is a co-occurrence such as ASD and ADHD.