Touching a cause of autism
When Arjun (name altered to maintain patient confidentiality) was about eight years old, one of his teachers decided to tickle him along his arm, when he was playing. Normally kids enjoy such interactions, often accompanied by peals of laughter. But it was not the case for Arjun.
Arjun flinched, pushed her hand away sharply, recoiling at this interaction and avoided her for sometime.
Arjun is afflicted with Autism spectrum disorder (ASD). As the name suggests, ASD alludes to a range of conditions that are characterized by neurological and developmental disorders. According to the World Health Organization, ASD affects 1 in 160 children, with signs of autism developing between 2-3 years of age.
Repetitive behaviors, hyperactive responses to sensory experiences, problems in social interaction and communication are some of the hallmarks of ASD. Most commonly, patients with ASD experience an aversion to touch sensation.
When asked about touch aversion, the President of the Association for Behavior Analysis- India, Ms. Gita Srikanth says, "The one thing I have noticed is their lack of ability to modify their touch intensity depending on the moment, the person and the context."
Ms. Srikanth is also the Director of 'We Can', a resource center for Autism established about 15 years ago in Chennai, a city in Southern India - where Arjun is a student.
The importance of touch
A parent's touch is an integral part of a child's overall development giving rise to a sense of security - yet in the case of kids with ASD that appears to be a curse! So when a child reacts abnormally to touch, could it affect their growth and mental development? Is there any scientific evidence in favor of this relationship?
"This is why researchers at Harvard Medical School led by Dr. David Ginty, wondered whether in ASD, there was a role for the peripheral nervous system (PNS), where sensory neurons around the spinal cord conduct feelings from the body to the brain", says Dr. Emanuel DiCicco-Bloom who is a Child Neurologist and Developmental Neuroscientist at Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, and an independent expert not associated with the study.
Now, how do we feel touch? It is the nerve endings underneath our skin, part of the peripheral nervous system (PNS), which feel and respond to touch. The peripheral nerves communicate touch inputs, amongst others to the brain.
"One important question is how these changes in peripheral sensory responsiveness relate to other behavioral abnormalities found in autism," says Dr. Ted Abel, the Brush Family Professor of Biology at University of Pennsylvania, another independent expert not directly involved in the study.
Among other symptoms, ASD is characterized by a hyper active responsiveness to sensory experiences. Imagine for a light touch to the skin you react as though you heard a loud and irritating noise! Hence, the recoil reaction is natural in this context. "Patients often find that treatment to reduce this sensory hyper-responsiveness can improve other behaviors," comments Abel, on the association between disease and sensory response.
Typically, research concerning neurological disorders is carried out in animal models. But what about disorders such as autism? Do rodents experience it, for instance? Not necessarily.
"Autism is a uniquely human disease, as neither (non-human) primates nor rodents have autism. Therefore, we generally think that the behavioral changes in autism, like difficulties with social interactions and anxiety, are caused by changes in the most recently evolved brain regions like the forebrain," explains DiCocco-Bloom.
However, Dr. Ginty and his colleagues decided to approach the problem from a completely different angle.
They conducted their study using genetically engineered mouse models. The researchers altered specific genes associated with ASD in the Peripheral Nervous System, at specific time points in the mouse growth- baby versus adult mice - and at specific locations, to test how they respond to touch.
The experiments involved tricking the mouse into believing that they were experiencing a mild touch sensation by applying a light air puff to the back of their hairy skin. And what did the researchers find?
Compared to normal mice, the genetically engineered autistic mice displayed heightened responses to the air puffs. Also, these responses were enhanced in young mice compared to their adult counterparts.
While conventional beliefs dictated that autism is caused only by disorders in brain development, the study highlighted that defects restricted to the PNS could also lead to anxiety like behaviors and social deficits.
The researchers describe the exaggerated reaction to touch, akin to a 'volume' control mechanism in the nerve endings beneath the skin.
Imagine you touch silk, but you feel as though you touched fire! And this PNS hyper-responsiveness is because the volume for these neurons is completely dialed up in response to touch.
Explaining the importance of such a study Dicocco-Bloom adds, "The authors emphasize the importance of proper sensory information to support the emergence of normal social and cognitive behaviors during development, and liken the findings to well recognized deficits in cognition, language and social behaviors shown by institutionalized children brought up with low caregiver physical and emotional investment."
Although this is a breakthrough study, experts warn that there a number of challenges facing ASD.
Understanding the spectrum of Autism
"Currently, we have no effective treatment for the behavioral challenges experienced by individuals with autism, though there are reports that deep touch pressure can be calming in patients, as described by Temple Grandin," says Abel.
Dicocco-Bloom comments about a slew of recent scientific studies, which have identified nearly 500-1000 genes, while there are several as yet unidentified environmental factors contributing to autism. "Thus while we identify autism as difficulties with social interaction and repetitive behaviors, the actual specific causes for any individual may be relatively unique, though the symptoms of the disorder may appear the same," he adds.
This brings us to the critical issue of individualized patient care and the concept of personalized medicine, as in the treatment for cancer.
As a result, "we consider not simply autism, but the 'autisms'," says Dicocco-Bloom. Furthermore, he explains that in order to treat each individual afflicted with ASD, with either behavioral or pharmacological therapies, we may need to study each person directly and understand what is the exact cause of autism. This is an emergent phenomenon in the healthcare industry.
Another interesting conclusion from this study is that not all Genetically Modified Organisms (GMOs) need to be met with contempt!
In fact, genetically engineered mice are the secret for bringing Ginty and his team's study to fruition.
As the first author of the study, Dr. Lauren Orefice points out, "Genetic mouse models of ASD can provide important insights regarding mechanisms, which underlie the causes of ASD and how we might improve symptoms in mice that are analogous to human behaviors."
Abel concludes, "These mice underscore the complex interaction between our sensory experience of the world and our behavior."
So while we wait for research to transition from "bench-to-bedside" and find a permanent cure, what is the fate of children afflicted with ASD? And how can families with autistic children and society cope with it?
This is where organizations like 'We Can' play a huge role by offering behavioral interventions to improve communication and independent life skills.
As for Arjun, he is now 18 years old, and is still with 'We Can'- learning new work skills.
"We get Arjun to do some basic work for us part of the day, while he weaves and learns other skills the rest of the day, including games and exercise. But he never developed any vocals and so he uses signs to communicate his basic needs. He remains a person who does not like too much proximity and touch," says Srikanth.
However, adds a buoyant Srikanth, "His family has encouraged him to paint and they display his work in local exhibitions. He enjoys weaving on a loom, and makes great tea. He is one happy guy!"
Image credit: https://unsplash.com/photos/-FpPX9bvcN4 (Laura Lee Moreau)