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Updated: Jan 20, 2026
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Meta-analysis of Voxel-Based Neuroimaging Studies using Seed-based d Mapping with Permutation of Subject Images SDM-PSI
Published on: November 27, 2019
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Temporal Changes in Effect Sizes of Studies Comparing Individuals With and Without Autism: A Meta-analysis
Eya-Mist Rødgaard1, Kristian Jensen2, Jean-Noël Vergnes3,4
1Department of Psychology, University of Copenhagen, Copenhagen, Denmark.
JAMA Psychiatry
|August 22, 2019
Summary
Autism research shows decreasing effect sizes over time, suggesting broader diagnostic criteria may impact study findings. This trend may hinder the development of mechanistic models for autism spectrum disorder.
Area of Science:
- Neuroscience
- Psychology
- Psychiatry
Background:
- Autism's definition has evolved, shifting from a categorical to a spectrum-based view.
- This evolution has coincided with increased autism prevalence and potential heterogeneity.
- Changes in diagnostic criteria may influence autism research outcomes, particularly effect sizes in group comparisons.
Purpose of the Study:
- To investigate the relationship between publication year and effect size in neurocognitive research comparing individuals with autism and control groups.
- To analyze temporal trends in effect sizes across various autism neurocognitive domains.
Main Methods:
- A meta-analysis of 11 existing meta-analyses published between 1966 and 2019 was conducted.
- Studies were included if they reported significant group differences in neurocognitive constructs and spanned at least 15 years.
- Data extraction and synthesis followed PRISMA guidelines using fixed-effects models.
Main Results:
- A downward temporal trend in effect size was observed across all analyzed neurocognitive constructs.
- Significant negative trends were found for emotion recognition, theory of mind, planning, P3b amplitude, and brain size.
- In contrast, analogous constructs in schizophrenia did not exhibit similar temporal trends.
Conclusions:
- The findings indicate a decrease in effect sizes for autism-related group differences over time.
- This trend may be linked to evolving, more inclusive definitions of autism, increasing population heterogeneity.
- Increased heterogeneity could potentially reduce the capacity for building robust mechanistic models of autism.
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