The Wechsler Intelligence Scales are standardized tests designed to measure cognitive abilities in children and adults.
For children aged 6-16, the Wechsler Intelligence Scale for Children (WISC) is commonly used. It assesses various cognitive domains, including verbal comprehension, perceptual reasoning, working memory, and processing speed, to generate a Full Scale IQ score.
In individuals diagnosed with autism spectrum disorder (ASD) or attention-deficit/hyperactivity disorder (ADHD), the relationship between intelligence and academic achievement may be more complex than in the general population.
These neurodevelopmental disorders can affect cognitive processes differently, potentially leading to uneven skill profiles.
For instance, an autistic child might have above-average intelligence but struggle with specific academic tasks due tosocial communicationchallenges. Similarly, a child with ADHD may have average intelligence but underachieve academically due to difficulties with attention andexecutive functioning.
Key Points
Rationale
The study aimed to examine if Wechsler intelligence scales predict academic achievement and/or grades in children with ADHD and/or ASD.
This research is important because:
What we know:
Intelligence tests are robust predictors of academic achievement in the general population (Deary et al., 2007; Neisser et al., 1996; Plomin & von Stumm, 2018).
Next step:
While numerous studies have examined IQ, WISC profiles, and academic achievement in ASD and ADHD separately, there was a need to systematically review and meta-analyze the relationship between Wechsler intelligence scales and academic achievement specifically in these populations.
This research helps clarify the role of IQ in academic achievement for children with ADHD and ASD, which is crucial for developing appropriate educational interventions and support strategies.
Understanding this relationship is particularly important given the heterogeneous nature of these neurodevelopmental disorders and the varying cognitive and academic profiles observed within these populations (Thaler et al., 2013; Mayes & Calhoun, 2008).
Method
Thesystematic reviewandmeta-analysisfollowed the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) guidelines.
Three databases were searched: PubMed, PsycINFO, and Education Research Complete.
The search strategy included a combination of three key elements:
Specific search terms for each database were provided in a supplementary table.
Inclusion criteria:
Exclusion criteria:
Statistical measures
The meta-analyses were conducted using the tool Meta-Essentials, employing a random effects model due to expected heterogeneity across studies.
The I² statistic was used to assess heterogeneity. Publication bias was assessed with funnel plots including the results of a trim-and-fill procedure.
Results
Study selection and characteristics:
Risk of bias assessment:
Narrative synthesis:
Meta-analysis results (ADHD only):
Insight
The study provides evidence that Wechsler intelligence scales, particularly FSIQ and PSI, are moderately predictive of academic achievement in children with ADHD across reading, written language, and mathematics.
For children with ASD, while the evidence is more limited, FSIQ, WMI, and PSI appear to be significant predictors of academic achievement.
The study highlights that while intelligence is an important factor, other characteristics related to ADHD or ASD may affect the strength of this relationship.
Future research could focus on:
Strengths
Below are some of the strengths of this review:
Limitations
Below are some of the limitations of this review:
These limitations suggest that the findings should be interpreted cautiously, particularly for the ASD population.
The heterogeneity in samples and measures also indicates a need for more standardized approaches in future research.
Implications
The results have significant implications for educational and clinical practice:
References
Primary reference
Marinopoulou, M., Åsberg Johnels, J., Bornehag, C. G., Unenge Hallerbäck, M., & Billstedt, E. (2024). Do Wechsler intelligence scales predict academic achievement in children with ADHD or autism? A systematic review and meta-analysis.Applied Neuropsychology: Child, 1–15.https://doi.org/10.1080/21622965.2024.2361022
Other references
Deary, I. J., Strand, S., Smith, P., & Fernandes, C. (2007). Intelligence and educational achievement.Intelligence,35(1), 13–21.https://doi.org/10.1016/j.intell.2006.02.001
Ferrer, E., Shaywitz, B. A., Holahan, J. M., Marchione, K., & Shaywitz, S. E. (2010). Uncoupling of reading and IQ over time: Empirical evidence for a definition of dyslexia.Psychological Science,21(1), 93–101.https://doi.org/10.1177/0956797609354084
Neisser, U., Boodoo, G., Bouchard, T. J., Jr, Boykin, A. W., Brody, N., Ceci, S. J., Halpern, D. F., Loehlin, J. C., Perloff, R., Sternberg, R. J., & Urbina, S. (1996). Intelligence: Knowns and unknowns.American Psychologist,51(2), 77–101.https://doi.org/10.1037/0003-066X.51.2.77
Plomin, R., & von Stumm, S. (2018). The new genetics of intelligence.Nature Reviews. Genetics,19(3), 148–159.https://doi.org/10.1038/nrg.2017.104
Quinn, J. M., Wagner, R. K., Petscher, Y., Roberts, G., Menzel, A. J., & Schatschneider, C. (2020). Differential codevelopment of vocabulary knowledge and reading comprehension for students with and without learning disabilities.Journal of Educational Psychology,112(3), 608–627.https://doi.org/10.1037/edu0000382
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Saul McLeod, PhD
BSc (Hons) Psychology, MRes, PhD, University of Manchester
Saul McLeod, PhD., is a qualified psychology teacher with over 18 years of experience in further and higher education. He has been published in peer-reviewed journals, including the Journal of Clinical Psychology.
Olivia Guy-Evans, MSc
BSc (Hons) Psychology, MSc Psychology of Education
Olivia Guy-Evans is a writer and associate editor for Simply Psychology. She has previously worked in healthcare and educational sectors.
