Behavioral Measure of Reward for Restricted Interests in Autism Spectrum Disorder

Background: Autism spectrum disorders are complex, behaviorally-defined developmental disorders whose diagnosis by DSM IV-TR (2000) criteria requires clear evidence of dysfunction in three domains: social relatedness, communication, and restricted or repetitive behavior. The third domain may manifest in a variety of ways, one of which is a tendency for intense, circumscribed interests that may be pursued to a degree that interferes with daily life. So compelling are these interests for children with autism that they are often used in the classroom as motivational tools, suggesting that they are highly rewarding. Objectives: The goal of this study was to quantify the reward value of images related to these restricted interests by allowing participants to control the display duration of images either related or unrelated to their specific interest. Methods: Two groups, autism and control, were presented with images related or unrelated to their interests while asked to press a button either to increase or decrease the display time for each respective image. There were ten children in each group, ranging in age from eight to seventeen years of age. An inclusion criterion for controls was the presence of a strong hobby or interest. The parents of children in both groups were interviewed using the Yale Special Interests Interview (YSII) (South et al., 1999) to assess and score the severity of interference to the subject's own functioning in daily life due to the restricted interests/interests. Results: We found that the autism group's button presses resulted in longer display times for their own interests compared to controls' presses for their own interests. There was no significant difference in display time between the groups when presented with unrelated images. We also found a positive correlation between interference in daily life as measured by the YSII and the time of the restricted interest displayed. Conclusions: Individuals with autism will often work and make extreme efforts to gain access to objects, activities, or media related to their restricted interests to the detriment of other behaviors. The possibility of a relationship between the extent of the rewarding nature of restricted interests and the detriment to daily social activities is supported in this study. Expansion of this behavioral study using fMRI is currently underway in our laboratory to determine whether brain reward circuitry is involved when viewing images related to restricted interests in autism.