Evaluating the Cognitive Profile of Autism Spectrum Disorder

Background: It was previously believed that autism spectrum disorder (ASD) was related to significantly limited cognitive functioning (Goldberg Edelson, 2006). However, it is now understood that individuals with ASD can have a range of intelligence levels (Klinger, O’Kelley, & Mussey, 2009). While not a core symptom, the intelligence level of an individual with ASD has a large impact on their symptom severity (Harris & Handleman, 2000; Klinger et al., 2009; Lincoln, Allen, & Kilman, 1995). Mixed findings on the relationship between intelligence and ASD range from finding higher levels of intellectual disability in the population to significant differences between verbal and nonverbal intelligence (Tsatsanis, 2005; Volkmar, Lord, Bailey, Schultz, & Klin, 2004).

Objectives: The current study examines the cognitive functioning of multiple groups with ASD in order to add to the body of literature and update it to be relevant to DSM-5 changes in our conceptualization of ASD. Overall differences in IQ performance were compared between ASD and non-ASD groups. Age and IQ performance were compared, as well as sex differences and IQ performance. It was hypothesized that individuals with ASD will have significant differences in their nonverbal and verbal IQ scores, overall IQ differences would not be found between individuals with ASD and non-ASD individuals, younger children with ASD would have a significant strength in nonverbal IQ scores, and females with ASD would have higher verbal IQ scores than males with ASD and experience greater differences in their verbal and nonverbal IQ performances compared to non-ASD females.

Methods: From data gathered from comprehensive diagnostic evaluations for ASD performed in upstate New York, the present study examined ASD using the Autism Diagnostic Observation Schedule, Second Edition (ADOS-2; Lord, Rutter, DiLavore, Risi, Gotham, & Bishop, 2012) and cognitive performance using the Stanford-Binet Intelligence Scales, Fifth Edition (Roid, 2003). There were n = 125 males and n = 53 females in the sample. Of those who were evaluated, n = 76 males and n = 20 females received an ASD diagnosis. The data were evaluated using multiple t-tests.

Results: The results supported some of the study’s hypotheses and not others. Overall, individuals with ASD were found to have a significant difference in their nonverbal and verbal IQ scores, t(95) = 3.12, p = .002. This is particularly present in older individuals with ASD compared to their typically developing peers, t(117) = 2.54, p = .01, and in females with ASD compared to typically developing females, t(51) = 2.17, p = .04.

Conclusions: This study provides important information on the cognitive functioning of individuals with ASD. The results indicate that older individuals with ASD are more likely to have discrepant cognitive profiles, as are females with ASD. Given that cognitive functioning remains a critical predictor of outcomes for individuals with ASD, it continues to be an important area to explore. This study provides new information on how individuals with ASD compare to a clinical sample of non-ASD individuals, further uncovering details on the complex cognitive profile of individuals with ASD.