Intelligence profiles of children and adolescents with high functioning autism spectrum disorder

In this paper we identify an endophenotype for individuals with Autism spectrum disorder – level 1 (ASD-1) and normal cognitive functioning using the Wechsler Intelligence Scale for Children – Fourth Edition with a clinical sample of 80 diagnosed ASD-1 children without intellectual disability (with FSIQ>70), and a comparison matched-paired control group (n = 80) combined for age, gender of children and parents’ level education. From results emerged that the clinical ASD-1 with High functioning group (ASD-1 HF) performed worse than the matched-paired control group on Processing Speed Index and Working Memory Index, reflecting the sensitivity of these measures to generalized cognitive impairment. This result is also confirmed by the absence of a difference between the ASD-1 HF and control groups in the General Ability Index and the large difference to the Cognitive Proficiency Index in favour of the control group. Again, 36% of ASD children had a rare and large difference between the 4 indices and then the FSIQ could be deemed uninterpretable as unitary and cohesive ability. We argue that the ASD-1’s cognitive profile cannot be interpreted as a unitary entity represented from simply FSIQ, but we can obtain a better assessment of cognitive level in ASD subjects using separately the General Ability Index and the Cognitive Proficiency Index.