Individuals with attention-deficit hyperactivity disorder (ADHD) and/or autism usually fare better when diagnosed earlier so that parents and caregivers can provide them with the appropriate support and medication as soon as possible.
The problem is that even though autism and ADHD are both becoming better understood by scientists and medical professionals, telling the two conditions apart remains challenging. However, researchers from South Australia were able to pinpoint biomarkers that could allow for these conditions to be accurately distinguished and diagnosed using a simple eye test.
What is ADHD?
ADHD is more common than autism, with the condition affecting around five to eight percent of children, primarily boys, and often persisting into adulthood.
There is a wide range of symptoms, mostly centered around inattention, hyperactivity, impulsivity, forgetfulness, disorganization, restlessness, and constant talking or noise-making. ADHD can often be effectively treated with stimulant medication like methylphenidate (Ritalin) and dexamphetamine.
What is autism?
Autism spectrum disorder (ASD) is not diagnosed as much as ADHD, affecting around one percent of the population. The challenges in diagnosing ASD come from the fact that the symptoms are quite diverse and are displayed in a range of severity.
Symptoms include experiencing hardship in picking up social cues, making social interactions difficult, and atypical focus on details. People with ASD often respond in unusual ways to certain sensations and experiences. Treatments for ASD are usually more education and adaptation-focused.
Why are the two conditions easily confused?
Although ADHD and ASD are very different conditions, sometimes their symptoms and behaviors overlap. Only observing behavior makes it difficult for medical professionals to ensure that their patients are being put on the most effective treatment paths. That’s why there’s been a lot of investment in identifying biomarkers that could make this process easier and more clear-cut.
A promising solution
Research optometrist from Finders University, Dr. Paul Constable, has been investigating how to detect Autism through retinal scanning for many years. We first wrote about his work in February 2020.
Now, in a new paper published in Frontiers in Neuroscience, Constable and a team hailing from the University of South Australia, McGill University, Montreal, University College London, and the Great Ormond Street Hospital in the UK claim to have identified a tell-tale bio signal.
The electroretinogram (ERG) signal that the team found has demonstrated its use in not only separating ADHD and autism cases from control cases but can clearly distinguish between them.
ERGs have been used as diagnostic tests by opticians since the 1940s to identify retinal disorders. They expose patients to flashes of light or light patterns while an electrode (in the form of a thin fiber or a contact lens) is in contact with the cornea. This allows the electrical activity in the retina to be recorded at the cornea in a non-invasive way.
The results of the study show that ADHD patients demonstrate high overall ERG energy levels while ASD patients demonstrate lower overall ERG energy levels than control patients.
“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 neurodevelopment conditions,” explains Constable. “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.”
Though more research is needed before this technique can be used to diagnose patients, the researchers believe that it can one day offer an effective diagnostic tool and could potentially be employed to identify even more neurological conditions.
