It takes years to figure out what’s bothering him, and even then it’s hard to pinpoint. To him, it’s just “too much.” He can’t explain it. He can’t verbalize his frustration – his anxiety – or give you a reason why because it’s not one thing – it’s everything. He’s overstimulated. He feels everything in extremes. It’s intense. His senses are overloaded.
(Child B) She can’t stop moving. She needs to touch everything – grab everything. Her nails are chewed down to the nub. She rubs her blanket between her fingers until the fabric is worn down to almost nothing. She tugs at her clothes and chews on her collar. She’s overly affectionate and far too physical with those around her. She turns the music up way too loud. She sits far too close to the TV. She absorbs her surroundings like a sponge. Then, she crashed. It wasn’t enough. Now it’s too much.
(Child C) As mom puts socks on his feet, she holds her breath. Please let the sock seams not be too much today. They’re the same socks as always, but they’ve been washed again. The day has barely started; both mom and son are already exhausted. It’s a chore to get dressed in the morning. Even his carefully selected wardrobe causes intolerable discomfort. He feels things in more detail – with more precision – with more everything. He can feel every thread count in his shirt.
Three different children with sensory hyper- or hypo- sensitivities, but not all of these children have Sensory Processing Disorder. Some may have autism. Some are just going through a phase much like another child might obsess over Paw Patrol or eat the same meal for weeks on end, but they’re all over or under responsive to sensory stimulation.
Research suggests that sensory processing issues may affect as many as 5% to 16% of school aged children to some degree or another (Owen, 2013), but many of these sensory processing issues may stem from other neuroanatomical differences. Many gifted children, children with autism, and children with other neurodevelopmental disorders suffer from hyper- or hypo- sensitivities. Research suggests that over 90% of children with autism suffer from sensory difficulties, but does that mean they also have Sensory Processing Disorder? Both of these spectrum disorders can be difficult to diagnose and even more difficult to separate.
From a clinical perspective, Sensory Processing Disorder is a neurodevelopmental disorder in which the brain has difficulties receiving and responding to sensory information – touch, smell, taste, and/or sound. Individuals may be sensitive to one, multiple, or all sensory information. Like other neuro-developmental disorders (ADHD, Autism, etc), SPD is a spectrum disorder that affects different individuals to varying degrees. While the DSM-5 does not recognize Sensory Processing Disorder, the Taxonomy of Sensory Processing Disorder (2008) identifies three main categories of SPD: Sensory Modulation Disorder (Type I), Sensory Discrimination Disorder (Type II), and Sensory Based Motor Disorder (Type III).
What causes Sensory Processing Disorder?
Researchers have not identified a singular cause for SPD, but it is more common in children who (1) have parents with SPD (suggesting a genetic correlation), (2) were born prematurely, (3) encountered prenatal or birth complications, (4) are gifted, and/or (5) have autism. Strong evidence suggests a correlation between premature birth and SPD – specifically preterm children with cerebral white matter damage and/or noxious effects of environmental factors in the NICU (Broring, 2017).
At this time, it is difficult to distinguish between individuals with Autism who have sensory processing difficulties as a result of Autism and those individuals with both Autism and SPD. Similarly, it is difficult to identify whether or not sensory processing difficulties may or may not be correlated to high IQ.
Sensory Processing Disorder and the Brain
Sensory Processing Disorder is linked to abnormal white matter in the brain, specifically in the multi-sensory cortical brain areas. White matter fills nearly half of the brain and plays a vital role in learning and cognitive function. White matter connects different areas of grey matter across the brain and allows signals to pass from one region to another. It serves as the communication system within our brain. White matter houses axons, long threadlike nerve fibers that transmit information across the brain like a telephone wire. Neurotransmitters, chemical messengers, travel along axons to carry messages from one neuron to another. Since neurons in the brain are not actually touching, they must “jump” across synapses (the gaps) from one neuron to another.
In a neurotypical brain, this exchange is simple – several organized and scheduled transfers occur to carry a message to its final destination in a timely manner. In a neurodivergent brain with SPD, these transfers are more frequent and often disrupted. The transmissions are unable to diffuse smoothly across axons. As such, the message may be delayed or jumbled.
Research out of the University of California confirmed this theory using an advanced form of MRI called diffusion tensor imaging (DTI). They looked at differences in Fractional Anisotropy (FA), Mean Diffusivity (MD), and Radial Diffusivity (RD). In essence they sought to detect differences in the white matter of children with and without SPD. They found abnormal white matter in areas of the brain associated with multisensory integration suggesting a neurobiological basis for SPD that distinguishes it from other neurodevelopmental disorders such as Autism and ADHD.
Sensory Processing Disorder – vs—Autism
Some children with Autism have SPD, others may simply (or not so simply) present with sensory processing difficulties as a symptom of Autism. Autism, unlike SPD, is linked to an abnormal corpus callosum, the largest white matter structure of the brain. This structure is responsible for the connection between the right and left hemisphere of the brain. The left hemisphere, responsible for logic, analytic thinking, and objective thinking, “controls” the right hemisphere which is responsible for creativity and the arts. More complex connections between the right and left hemisphere may also contribute to hyper- and hypo- sensitivities – especially the reaction one has to sensory stimulation.
Since children with Autism are already neuro-divergent, it is also quite likely that this makes them more susceptible to Sensory Processing Disorder and the neuroanatomical distinctions correlated with it. Individuals with Autism may indeed also present with abnormal multi-sensory cortical areas in addition to an abnormal corpus callosum. As a result, this individual would have both SPD and Autism.
Currently, we treat both an individual with sensory processing difficulties as a result of Autism and an individual with Autism and SPD the same. However, further research regarding the neuroanatomical differences between the two can help assist therapists and medical professionals in the proper treatment for each individual. For children with Autism, we must work on coping strategies and therapies that help improve left-right brain connections. In contrast, a child with SPD needs therapies that target their reactions to sensory inputs.
Sensory Processing Disorder –vs— Gifted
Our gifted children often have a higher acuity to see connections where others do not. They learn more rapidly, more efficiently, and more deeply. They possess a sort of non-standard creativity that allows them to correlate memories, experiences, and knowledge to new information and produce giant “leaps” in understanding. In “Are Gifted Minds Wired Differently,” I reviewed research by John Geake, co-founder of the Oxford Cognitive Neuroscience-Education forum. He assessed that, “’gifted subjects have greater interconnectivity between different areas of their brain’ -- rooted in several neurobiological differences including: a thicker cerebral cortex, superior cognitive control, greater working memory, and better spatial and temporally coordinated neural networks -- a suggestion that gifted minds are, indeed, wired differently.” Gifted minds demand higher levels of input and a deeper understanding of real-life implications.
Many of our gifted children present with difficulties processing sensory information – either hyper- or hypo- sensitive, but may not have Sensory Processing Disorder. Our gifted children often take in more information – more sensory inputs – at a given moment to draw creative conclusions. This can cause the brain to feel “overloaded” and, as such, make it more difficult for a child to tolerate certain sensory stimulation. For some of our gifted children, I believe, that certain sensory stimulation aggravates their deep thought patterns. There may already be so many layers of complex thoughts floating around at any given time that certain additional stimulation is just “too much.” For under-responsive children, they are often so deep in thought that they are, perhaps, too preoccupied to pay certain sensory stimulation any mind.
What to Do
While sensory processing difficulties may stem from different neuroanatomical differences, we must recognize that these struggles are very real. As parents and educators, we must support them and provide them with proper resources.
Children with sensory processing difficulties may benefit from occupational therapy. Occupational therapists help people of all ages with daily activities and skills. Occupational therapists can help children with coordination, focus, organization skills, executive functioning, fine and gross motor delays, and sensory responses.
If your child attends private or public school, some simple accommodations may help make your child’s day more tolerable. Some suggestions include: building sensory breaks into the day, providing advanced warnings and schedules for loud noises or significant environmental changes, sitting in front of the class to avoid visual distractions, providing fidget toys for sensory seeking children, sound cancelling headphones during independent study/work periods, and alternative seating such as chairs, pillows, bean bags, floor time, etc.
Early intervention and parental awareness have a tremendous impact on the progress a child with sensory processing difficulties makes in coping with these struggles. Child A is still hyper- sensitive, but a psychologist helped him find coping strategies that changed his life. He learned practical strategies to communicate these intolerances to others and found nonintrusive ways to adapt his daily life to suit his needs. Child B acquired healthier coping strategies, and her sensory processing difficulties are hardly noticeable in adult life. Child C has adapted, and his hyper-sensitivity issues significantly diminished by adolescence.
Sensory processing difficulties may never “go away,” but coping strategies and various therapies can help make these issues more tolerable and even less noticeable over time.
Chang, Y. S., Owen, J. P., Desai, S. S., Hill, S. S., Arnett, A. B., Harris, J., ... & Mukherjee, P. (2014). Autism and sensory processing disorders: shared white matter disruption in sensory pathways but divergent connectivity in social-emotional pathways. PloS one, 9(7), e103038.
Diagnostic criteria for307.59 Feeding Disorder of Infancy or Early Childhood. (n.d.). Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR). doi:10.1176/appi.books.9780890423349.8006
Owen, J. P., Marco, E. J., Desai, S., Fourie, E., Harris, J., Hill, S. S., . . . Mukherjee, P. (2013). Abnormal white matter microstructure in children with sensory processing disorders. NeuroImage: Clinical,2, 844-853. doi:10.1016/j.nicl.2013.06.009
Sensory Processing Disorder and High Learning Potential. (2016, August). Retrieved from https://www.potentialplusuk.org/wp-content/uploads/2016/08/Sensory-Processing-Disorder-and-HLP.pdf