An unusually large public response is building to the first evidence of a biological basis for Sensory Processing Disorder (SPD). Some say SPD impacts up to 13% of kids. Others say it doesn’t exist as a distinct disorder. But tens of thousands are clicking on stories about the evidence, reposting them, and commenting.
Since July 9, when the paper detailing the evidence came out, some 15,231 Bioscience Technology readers viewed the announcement. The head of an SPD society has “hundreds of unread emails” in her inbox. NBC’s Today show scheduled a segment.
Also happy: the paper’s authors.
“The results were pretty remarkably strong,” says Pratik Mukherjee, professor of radiology and biomedical imaging and bioengineering at the University of California, San Francisco (UCSF). He conducted the study’s brain imaging. “I’ve never seen results that robust before in a relatively modest sample size. In other studies I have done, for a small number of subjects, it was very hard to find a significant effect. Here it was kind of jumping out at us. So there is likely something very important here. Very significant.”
Agrees Alice Carter, director of the University of Massachusetts Boston PhD Program in Clinical Psychology, an autism pioneer not involved with the trial: “As noted by the authors in the study, it is critically important to replicate these findings in a larger sample. All single studies can yield spurious results. But these results seem consistent with hypothesized mechanisms. This is a very important study. It is the first to use advanced neuroimaging methods to demonstrate that, when compared to typically developing boys, boys with SPD disorders (matched on age and IQ) show structural brain differences.”
Carter, also an associate research scientist at the Yale University Child Study Center, and a research associate in the Boston University Medical School Department of Anatomy and Neurobiology, says the study may persuade some critics who say SPD is a variant of autism, or attention deficit hyperactivity disorder (ADHD).
“Attitudes and beliefs can be hard to change even in the presence of strong data. I think this kind of work is exactly what is needed. A small group of studies this powerful should begin to change minds.”
She adds: “My own beliefs and attitudes were shifted by my data. I came into the field agnostic or even skeptical. Now I recognize many children are suffering from primary disturbances in sensory regulation. More research is needed to understand better identification and intervention.”
Once called sensory integration disorder, SPD began to catch on as a diagnosis—if still unrecognized by the Diagnostic and Statistical Manual of Mental Disorders (DSM)—in the 1970’s. Occupational therapists were seeing many children who had clear sensory problems. They were over-stimulated, or under-stimulated, by sounds, sights, textures, movement. The brains of these children were not registering sensory stimuli properly, confusing and frightening them, throwing them off balance, challenging their physical and emotional relationship with the world.
Clearly, many children with other disorders also possessed sensory processing problems. But many children without other disorders could exhibit powerful signs of SPD, as well, advocates say.
Indeed, kids with such disorders can experience a touch, even the pull of gravity, as “primary threats to survival,” says occupational therapist Lindsey Biel, who co-wrote "Raising a Sensory Smart Child," and an upcoming W.W. Norton book for clinicians on SPD. "They can feel safer low to the ground, avoiding movements that make them dizzy or disoriented."
Yet Biel and other occupational therapists say that, because it is not recognized as a distinct disorder in the DSM—despite passionate lobbying by many advocacy groups as recently as this spring-- insurance coverage can be hard to acquire.
“So this first study validating differences in brain microstructure is pretty exciting,” Biel says.
The study, led also by Elysa Marco, a cognitive and behavioral child neurologist at UCSF Benioff Children’s Hospital, examined the brains of 16 boys, aged 8-11, diagnosed with SPD alone. The study used diffusion tensor imaging, which Mukherjee was earlier among the first to apply to child brain development. It measures the movement of water along tracts in brain white matter. The white matter is filled with axons, hooking up brain regions.
The imaging clearly showed deficits exactly where one would predict changes in basic sensory perception and integration: areas in the back of the brain that connect sensory input to cognitive processing. In general, findings for children with autism and ADHD have implicated other regions, Marco notes.
“Boys with SPD evidenced reductions in white matter microstructures, primarily in posterior cerebral tracts relative to typically developing boys,” says Carter. “Of great interest, the degree of reduction in posterior white matter microstructural integrity in the boys with SPD was correlated with parent ratings of atypical sensory behaviors. This supported a link between the integrity of these structures and degree of sensory sensitivities.”
She continues: “Importantly, all of the children had Above Average cognitive abilities, assessed with standardized IQ tests, and none met criteria for a diagnosis of an autism spectrum disorder (ASD). Although children with ASDs and other intellectual and developmental disabilities (IDD) are more likely to suffer from impaired sensory symptoms, SPD is a significant clinical problem for many children who do not have co-occurring conditions such as ASD and IDD.”
In their next SPD study, Marco and Mukherjee plan to include kids with ASDs, girls, diverse age groups. Carter agrees this is key. Also key: determining if direct symptom assessments, more than parent reports, “lead to greater specificity of association between brain regions of interest and specific sensory modalities.”
A more guarded--if interested--observer is Larry Desch, lead author of a 2012 American Academy of Pediatrics recommendation that, "at this time," clinicians avoid SPD diagnoses. "Intriguing findings," he says. But as the study offered "only 16 subjects, and a full description of their problems was not divulged, more research needs to be done before we are very sure."
Meanwhile, the emails keep coming. Every day groups of grateful parents—sometimes ten at a time—write Marco.
“I think that is because this is such a burning question, for so many,” says Mukherjee.
Says Marco: “It’s as if a well, dry for a lifetime, is suddenly running fresh clean water. People just can’t believe it.”
Marco is a member of the SPD Scientific Work Group, a global consortium of top SPD experts supported by the SPD Foundation. The SPD Foundation is headed by SPD researcher Lucy Jane Miller, who authored "Sensational Kids" and the preface of Carol Kranowitz's "The Out of Sync Child." Miller is a key driver in the movement to classify SPDs in diagnostic manuals.