When a child finds it difficult to process and act upon information received through the senses, this is called sensory processing disorder (SPD), a neurological condition which often leads to clumsiness, anxiety, depression, behavioral problems, and even learning issues. In a new study, researchers show how children with sensory processing disorders have decreased connections in specific regions of the brain, in some ways similar and in other ways distinct from the neurological areas impacted by autism. “This study is the first to investigate white matter connectivity of both children with SPD and children with [autism] relative to typically developing children,” note the authors.

More than 90 percent of children with autism spectrum disorders (ASD) demonstrate unusual sensory behaviors. A child with autism, for example, may over-respond to physical sensation, going so far as to find physical contact and even clothing to be unbearable. However, there are children with similar sensory behaviors, sometimes to a greater degree, who do not meet an ASD diagnosis. "With more than one percent of children in the U.S. diagnosed with an autism spectrum disorder, and reports of five to 16 percent of children having sensory processing difficulties, it's essential we define the neural underpinnings of these conditions, and identify the areas they overlap and where they are very distinct," said Dr. Pratik Mukherjee, senior author and a professor of radiology and biomedical imaging at the University of California, San Francisco.

To explore these conditions, Mukherjee and his colleagues used an advanced brain scan known as diffusion tensor imaging (DTI), which measures the microscopic movement of water molecules as a way to provide information about white matter tracts. White matter is essential for perceiving, thinking and action; it is the site of all the "wiring" that connects different areas of the brain. For the study, the researchers used DTI to examine white matter tracts in16 boys with SPD and 15 boys with autism and then compared the results with those of 23 typically developing boys. All of the boys were between the ages of 8 and 12.

What did the researchers discover? Compared to the typically developing group, both the SPD and autism groups showed decreased connectivity in multiple tracts in the back of the brain — areas that handle basic sensory information. However, only the kids with autism showed impairment in tracts critical to social-emotional processing. Meanwhile, kids with SPD showed less connectivity in areas of the brain which connect the auditory, visual and tactile systems involved in sensory processing.

Going forward, the researchers believe their work could be useful to those who work with children suffering from SPD. Measuring and keeping tabs on a child’s white matter, in a manner similar to how it was done in this study, might help therapists see whether a particular intervention is actually having an effect on brain connectivity.

Source: Mukherjee P, Chang YS, Marco E, et al. Autism and Sensory Processing Disorders: Shared White Matter Disruption in Sensory Pathways but Divergent Connectivity in Social-Emotional Pathways. PLOS ONE. 2014.