Reading Comprehension Impairments in Higher Functioning School-Aged Children with ASD

Background:  

The development of adequate reading comprehension by the end of the elementary school years is essential to subsequent academic achievement, cognitive development, and ultimately vocational success (National Reading Panel, 2000).  Recent research has raised the hypothesis that reading comprehension impairment may be part of the social communication phenotype of higher functioning school-aged children with ASD (Norbury & Nation, 2011; Randi, Newman, & Grigorenko, 2010; Ricketts et al., 2013). 

Objectives:  

This study was designed to assess reading comprehension, its component skills, and possible moderating factors such as comorbid ADHD, in a large sample (N=79) of younger (8-11 yo) and older (12-16 yo) higher functioning students with ASD (HFASD; FSIQ>75) using measures of text level comprehension and word level processing. 

Methods:  

The HFASD sample was compared to an age-matched Control sample (N=83), half of which had elevated ADHD symptoms.  Reading comprehension was measured with the standardized GORT-5 and a curriculum-based assessment, the QRI-5. Component/word level skills were assessed with the following scales:  TAPS-3 Auditory Reasoning (AR); CTOPP for Elision, Nonword Repetition, Rapid Digit/Letter Naming; TOWRE-2 Sight Word Efficiency (SWE), Pseudoword Efficiency (PDE); Derivational Morphology (J. Carlisle, 2000); CELF-4 Recalling Sentences (RS); WIAT Receptive Vocabulary.  The WASI was administered for IQ and Expressive Vocabulary; the ADOS-2 for ASD confirmation; the Conners-3 for ADHD symptoms.

Results:  

All analyses included FSIQ as a covariate. The results revealed that the HFASD sample scored significantly lower than Controls on GORT Comprehension, p<.000, eta² = .091; QRI Comprehension, p=.002, eta²=.065; CELF Recalling Sentences, p<.000, eta²=.088; Morphology, p=.008, eta²=.048; Receptive Vocabulary, p=.022, eta² = .036; and Expressive Vocabulary, p=.002, eta²=.063. There was no significant effect of Diagnostic Group on the remaining word level processing measures.   Analysis of GORT Comprehension Grade Equivalent scores revealed that, on average, younger children with HFASD (8-11 yo) obtained scores 1.3 grades below grade-level and older children with HFASD (12-16 yo) scored 2.4 grades below. In the total HFASD sample, 27% of the children scored  >3 grades below grade-level.  The subgroup with ADHD T-scores > 70 had lower QRI Comprehension scores in the Control but not the HFASD sample, p=.005, eta²= .055.  In the HFASD sample, ADOS-2 Total scores were significantly correlated with GORT Comprehension, r= -.319, p=.008; QRI Comprehension, r= -.247, p=.038; TAPS Auditory Reasoning, r= -.228, p=.05.

Conclusions:  

Students with HFASD may be vulnerable to reading comprehension impairments and cross-sectional data suggests that the expression of this vulnerability increases with age and development.  They may also be vulnerable to language impairments in both semantic and structural/syntactic domains.  HFASD children appeared to be less vulnerable to developmental impairment in word level processing.  Word level skills were a relative strength and not significantly different than those of their same-age peers.  The significant relations between both reading comprehension measures, the auditory reasoning measure, and ADOS scores was consistent with the hypothesis that their reading disturbance may be a part of the social communication phenotype of higher functioning school-aged children with ASD.