Fakhri Shafai

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VSS Best Poster Awards 2014

Orientation discrimination profiles identify distinct subgroups within autism spectrum disorder

Fakhri Shafai1,4, Kimberly Armstrong2, Grace Iarocci3, Ipek Oruc4; 1Graduate program in Neuroscience, University of British Columbia, 2Graduate program in Clinical Psychology, Simon Fraser University, 3Department of Psychology, Simon Fraser University, 4Department of Ophthalmology and Visual Sciences, University of British Columbia

The latest revision of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) included the decision to collapse previous diagnostic groupings into a single umbrella diagnosis of autism spectrum disorder (ASD). Although the idea of categorizing individuals on the ASD spectrum into well-circumscribed sub-groups is highly attractive, scientific evidence necessary to make such distinctions is currently lacking. Last year at VSS we presented data from a group of adults with ASD that showed two distinct clusters based on performance in an orientation discrimination task. One cluster had results consistent with the oblique effect, i.e., superior precision around cardinal axes, compared to oblique angles. The other cluster of ASD participants showed a complete lack of the oblique effect with flat profiles across all orientations.

We hypothesize that this clustering may be a reflection of true etiological sub-groups within ASD. To examine potential links between these clusters defined based on visual performance and ASD symptomology we collected the following neuropsychological measures on the same group of adults with ASD (N=19): 1) Wechsler Abbreviated Scale of Intelligence (WASI-II), 2) Autism Quotient (AQ), 3) Multidimensional Social Competence Scale (MSCS), and 4) Autism Diagnostic Observation Schedule (ADOS). A support vector machine pattern classifier was able to correctly predict which cluster an individual belongs to with generalization accuracy of 89.47% (p =0.01) based solely on Full IQ and gender. In addition, these clusters were also independently identified with 76.92% generalization accuracy based only on a single subscale of the MSCS assessing social motivation (p<0.05) based on a subset of our ASD group (N=13) who completed this measure. Our results suggest that visual performance profiles provide valuable information in identifying true etiological subgroups within ASD. In addition, they suggest that these visual protocols can serve as potential tools to improve diagnostic specificity.