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Neurodiversity and Intelligence: Evaluating the Flynn Effect in Children with Autism Spectrum Disorder

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Abstract

The Flynn Effect (FE) among child and adolescent populations indicates that intelligence scores improve by about three points per decade. Using nine years of data from the National Database for Autism Research, this study examined whether general intelligence changed significantly for nine cohorts with autism spectrum disorder (ASD; N = 671). Analyses demonstrated a downward trend such that Cohen’s d from 1998 to 2006 was − 0.27. The mean IQ is 92.74 for years 1–3, 91.54 for years 4–6, and 87.34 for years 7–9, indicating a reverse FE of 5.4 points per decade. A linear regression revealed a significant negative FE comparable to the positive effect of age on IQ among those with ASD. Implications for research, practice, and law are discussed.

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Acknowledgment

Data and/or research tools used in the preparation of this manuscript were obtained from the National Institute of Mental Health (NIMH) Data Archive (NDA). NDA is a collaborative informatics system created by the National Institutes of Health to provide a national resource to support and accelerate research in mental health. Dataset identifier(s): Package number 113988. This manuscript reflects the views of the authors and may not reflect the opinions or views of the NIH or of the Submitters submitting original data to NDA.

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Authors and Affiliations

  1. Department of Educational Psychology, Baylor University, Waco, TX, USA

    Kenzie B. Billeiter

  2. Department of Educational Studies, Purdue University, West Lafayette, IN, USA

    John Mark Froiland

  3. Department of Psychology, Sam Houston State University, Huntsville, TX, USA

    Justin P. Allen

  4. Division of Counseling and Psychology in Education, University of South Dakota, Vermillion, SD, USA

    Daniel B. Hajovsky

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  1. Kenzie B. Billeiter
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  2. John Mark Froiland
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Correspondence to Kenzie B. Billeiter.

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Billeiter, K.B., Froiland, J.M., Allen, J.P. et al. Neurodiversity and Intelligence: Evaluating the Flynn Effect in Children with Autism Spectrum Disorder. Child Psychiatry Hum Dev 53, 919–927 (2022). https://doi.org/10.1007/s10578-021-01175-w

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