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Saturday 25 Oct 2014

Anxiety and Sensory Over-Responsivity

In an article recently published to the Journal of Autism and other Developmental Disorders, the authors (Shulamite A. Green and Ayelet Ben-Sasson) discuss the concurrence of Autism Spectrum Disorders and anxiety and/or sensory over-responsitivity (SOR). In children with ASD, rates of anxiety are estimated to be 18-87% (3-24% in typically developing children). The rates of SOR are estimated to be 56-70% as compared to 10-17% in the general population of children. SOR has been linked to anxiety in children with ASD in three studies. Anxiety disorders in people with autism may add to functional impairments which impact their ability to engage in everyday activities and social interactions with others. In this article the authors presented three theories to explain the association and also discussed the implications these theories have on the treatment options.

What is anxiety?
In the article, anxiety is described as being characterized by hyperarousal which leads to a state of hypervigiliance. This means that the person with anxiety constantly scanning their environment for threat-relevant stimuli. Anxiety disorders are typically diagnosed by psychologists.

What is sensory over-responsivity?
In the article, sensory over-responsivity (SOR) is described as a person’s negative reaction to noisy or visually complex environments, tags or seams on their clothing or unexpected touch. SOR is typically diagnosed by occupational therapists.

How might anxiety and SOR be linked?

Theory 1: Anxiety Causes SOR
The authors propose that “anxiety contributes to SOR as hyperarousal and hypervigilance focus attention on a specific type of sensory stimulus. In this case, children who are hypervigilant and continuously scanning their environment are more likely to notice and react to aversive sensory stimuli in the environment. The threat-based emotion regulation associated with anxiety also makes it more difficult for children to regulate their emotional and physiological reactions to stimuli. The reaction may worsen through both classical and interoceptive conditioning.”

Theory 2: SOR Causes Anxiety
In their second theory, the authors propose that “SOR contributes to anxiety as a specific over-reaction generalizes to an environment or situation through context conditioning. The strength of the unconditional sensory reaction and the uncontrollability of events that elicit sensory stimuli contribute to stronger conditioning.”

Theory 3: Anxiety and SOR are not causally related
The authors theorize that anxiety and SOR may not be causally related, but they may be connected through a brain structure called the amygdala. They discuss the “possibility that a common risk factor such as amygdala abnormalities may contribute independently to each condition. The amygdala has long been known to play a role in fear and anxiety, and may also be related to SOR through overestimation of the threat value of a sensory stimulus which triggers an enhanced response to that stimulus.”

What are the implications of all this on intervention?
The authors discuss the common, yet separate, interventions for each diagnosis. For SOR, the commonly recommended and implemented interventions are sensory integration therapy (SIT), sensory diet, sensory stimulation, and auditory integration therapy. The only one of these interventions which has some supporting evidence, is sensory integration therapy. For anxiety, the most common methods of treatment are cognitive behavior therapy (CBT) and psycho-pharmacological treatments (i.e. SSRIs). Both of these common treatments for anxiety have been shown to be effect in reducing the symptoms of anxiety.

The treatment recommendations are typically based on the diagnosis, but the diagnosis given is many times dependent on the person giving the diagnosis. The authors of this study discuss the results of a study conducted by the second author in which they found that given the same vignettes, OTs were more likely to diagnose the person with SOR and psychologists were more likely to diagnose the person with anxiety. This is thought to be the case because the symptom profiles of the two disorders are very similar. This difference in diagnostics can impact the treatment given, which may greatly impact outcomes.

There is a lot more research that needs to be conducted to parse out the causal relationship between these disorders because that may indeed impact the treatment recommended and implemented. It may turn out that a combination of interventions (i.e. CBT + SIT) may be the most effective treatment option, but more studies are needed to make any conclusive statements regarding treatment options and efficacy.