Sensory Processing Disorder Research News

The term Sensory Processing Disorder (SPD) has been adopted to describe an umbrella term encompassing problems with sensory modulation, sensory discrimination, and sensory-based movement. (McIntosh, et al., 1999; Miller, et al., 2001; Schaff, et al., 2003; Miller, et al., 2007) Children with SPD have difficulty processing information from the senses (auditory, visual, vestibular, tactile, etc.) in order to formulate adaptive responses. SPD was originally called Sensory Integration Dysfunction, and it was first described in the 1970s by Dr. A. Jean Ayers, an occupational therapist with advanced training in neuroscience.

One subtype of SPD, Sensory OverResponsivity (SOR), has particular relevance to basic and treatment-based research in the mental-health field. Children with SOR react to sensory stimuli that others find neutral or pleasing as though the stimuli are aversive. When the environment is sensory-overloading, these individuals feel bombarded with stimulation. Behavioral manifestations include:

Irritability
Sadness
Anxiety
Aggression
Withdrawal

Because responses and consequent behavior depend upon changing sensory environments, these children are unpredictable, difficult to understand, and are frequently misdiagnosed by mental-health practitioners. However, recent research at the SPD Foundation (formerly KID Foundation) has revealed that there are specific nervous-system markers in children with SOR that account for the observed behavior.

Using electro-dermal activity and vagal tone as dependent measures, researchers at the SPD Foundation tested reactivity to various sensory stimuli across groups of children. (Miller, 2001; Schaff, et al, 2003) Children with SOR demonstrated:

Greater sympathetic responses (e.g., fight-or-flight responses) to stimuli
Weaker parasympathetic responses (e.g., the system that regulates us back to calm states, or homeostasis)

In other words, when presented with stimuli that typical children found benign, children with SOR responded more intensely (as though the stimuli were threatening), and they did not calm down as quickly or efficiently as typical peers. Lack of habituation may be critical for explaining the salient aspects of certain disordered psychological and behavioral functioning. All animals, including humans, alert to novel stimuli with physical arousal. Once it has been established that the stimuli are not threatening, the arousal level reduces significantly. For example, if we hear the sound of a lawn mower being powered up, our nervous systems alert to and attend to that sound. We become aroused. Once we determine that the sound is not a threat, the nervous system relegates it to the background and ceases to respond to it as if it were novel. (Schaff, et al., 2003) But SOR children tended to react as if repeated trials of the same sensory stimuli were novel each time, suggesting that they are in over-aroused, hyper-vigilant states throughout the day.

Preliminary studies of children with Attention Deficit Hyperactivity Disorder and Pervasive Developmental Disorders suggest different physiologic markers, supporting SPD as a valid syndrome separate from these other conditions that share symptoms. Further research at the SPD Foundation is likely to facilitate differential diagnosis between these developmental disorders and disabilities. Until SPD is included in the DSM and acknowledged universally among healthcare practitioners, many of the one million children estimated to be affected by the disorder will go untreated.

About the Author

Jennifer Jo Brout-Lynn, Ed.M., Psy.D., is a school/clinical child psychologist focusing on how Sensory Processing Disorders (SPD) impact mental health. She earned an Ed.M. from Columbia University and a Psy.D. from Albert Einstein College of Medicine. Currently, Dr. Brout is involved with projects at the KID Foundation Research Institute and Duke University and is in association with audiologists and private clinicians throughout the country. In 2006, Dr. Brout launched Positive Solutions of NY, LLC to support research on psychological conditions, developmental disorders, and learning difficulties through various creative and public service projects. Dr. Brout is also the mother of 13-year-old triplets and is on the advisory board of Mothers of Supertwins (M.O.S.T), a non-profit organization dedicated to supporting and researching multiple-birth children/families. She writes a quarterly column, “Ask the School Psychologist,” for M.O.S.T. which addresses the concerns of parents of school-aged multiple-birth children.

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Sensory Processing Disorder Research News