The Role of Hypersensitivity in Anxiety and Specific Phobia in ASD
Research indicates that anxiety disorders occur in 40% of youth with an ASD (van Steensel et al., 2011), and sensory abnormalities inherent to ASD may predispose youth to various manifestations of anxiety (Green & Ben-Sasson, 2010). Hypersensitivity to sensory stimuli has been associated with anxiety in youth with and without ASD (Pfieffer et al., 2005; Reynolds et al., 2005) and may be related to the development of traditional and unusual specific phobias in ASD (Koegel et al., 2004). Hypersensitivity may increase the likelihood that individuals become overwhelmed by and avoidant of specific stimuli – a trajectory that can lead to the development of specific fears and other anxiety concerns (Bellini, 2006). Whether sensory abnormalities are differentially related to the presentation of specific phobias versus other anxiety disorders in ASD is unknown, though testing this hypothesis will have important implications for anxiety prevention and treatment.
To assess the relationship of hypersensitivity to anxiety in ASD, and specifically to phobia, this study will examine parent reports of hypersensitivity in individuals with ASD alone (ASD group), ASD and specific phobia (ASD+Phobia group), and ASD and other anxiety disorders (e.g., social phobia, separation anxiety and generalized anxiety disorder; ASD+ANX group).
Participants were 53 youth (ages 7 – 17 years, M=10.59, SD= 2.81) diagnosed with ASD (79% male) as determined by the Autism Diagnostic Interview-Revised (ADI-R; Lord, Rutter, & LeCouteur, 1994), Autism Diagnostic Observation Scale (ADOS; Lord et al., 2000) and clinical judgment. All participants had a verbal IQ of 60 or greater on the Differential Ability Scales (DAS-II; Elliot, 2007). Forty-nine percent were taking medication. Hypersensitivity was measured via Likert ratings from the sensory sensitivity subscale of the parent-report Sensory Profile (Dunn, 1999). The Anxiety Disorders Interview Schedule- Child and Parent Versions (ADIS-C/P; Silverman & Albano, 1996) assessed anxiety disorders and specific phobias. Analysis of covariance assessed differences in parent-reported sensory sensitivity by group (ASD alone, ASD + ANX, ASD + Phobia), controlling for medication status.
Results indicated significant differences in sensory sensitivity between groups F (1, 49) = 6.38, p = .003, controlling for medication status, F (1, 49) = 3.65, p = .06. Post hoc contrasts indicated significantly increased sensory sensitivity in ASD+Phobia group (M = 4.35) versus the ASD group (M = 3.5; p = .003). By comparison, there were no significant differences between the ASD+ANX (M = 3.72) compared to ASD+Phobia or ASD groups. Additional item-level analyses are planned to detect symptoms underlying these associations and potential diagnostic overlap.
These preliminary findings indicate that specific phobia in ASD is associated with hypersensitivity to sensory stimuli. Hypersensitivity ratings were lowest for the ASD group and highest for the ASD plus phobia group, with ratings for youth with ASD and other anxiety disorders falling in the middle. Whether associations between anxiety and hypersensitivity in ASD reflect a true, theoretically informative relationship or a function of symptom overlap will be explored.