Inhibitory Control in Autism Spectrum Disorders: Meta-analyses on Indirect and Direct Measures.
When ASD and ADHD symptoms mix, expect sharper inhibitory-control and memory deficits—so screen and plan for both.
01Research in Context
What this study did
The team pooled 42 studies that measured inhibitory control in kids with autism.
They compared three groups: ASD alone, ASD plus ADHD symptoms, and neurotypical kids.
Tests were both direct (computer stop-signal games) and indirect (parent checklists).
What they found
Kids with ASD plus ADHD symptoms scored much worse on every inhibitory task.
Effect size was large: about one full standard deviation below ASD-only peers.
Adaptive living skills and working memory dropped just as sharply.
How this fits with other research
Reus et al. (2013) saw the same pattern first: parent ratings inflate when ADHD rides along.
Iversen et al. (2021) link poor inhibitory control to more repetitive behaviors, so the double diagnosis may worsen RRBs too.
Green et al. (2015) show even community kids with ADHD alone display extra ASD traits, proving the overlap is not just clinic noise.
Why it matters
Screen every child with ASD for ADHD symptoms before you write goals.
If both are present, plan shorter work periods, extra visual cues, and heavier reinforcement for impulse control.
Share the data with parents so they understand why skills like waiting or remembering multi-step directions are even harder for their child.
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02At a glance
03Original abstract
Recent estimates suggest that 31% of children with autism spectrum disorders (ASD) meet diagnostic criteria for attention deficit/hyperactivity disorder (ADHD), and another 24% of children with ASD exhibit subthreshold clinical ADHD symptoms. Presence of ADHD symptoms in the context of ASD could have a variety of effects on cognition, autistic traits, and adaptive/maladaptive behaviors including: exacerbating core ASD impairments; adding unique impairments specific to ADHD; producing new problems unreported in ASD or ADHD; having no clear impact; or producing some combination of these scenarios. Children with ASD and co-morbid ADHD symptoms (ASD+ADHD; n = 21), children with ASD without ADHD (ASD; n = 28), and a typically developing control group (n = 21) were included in the study; all groups were matched on age, gender-ratio, IQ, and socioeconomic status. Data were collected on verbal and spatial working memory, response inhibition, global executive control (EC), autistic traits, adaptive functioning, and maladaptive behavior problems. In this sample, the presence of ADHD symptoms in ASD exacerbated impairments in EC and adaptive behavior and resulted in higher autistic trait, and externalizing behavior ratings. ADHD symptoms were also associated with greater impairments on a lab measure of verbal working memory. These findings suggest that children with ASD+ADHD symptoms present with exacerbated impairments in some but not all domains of functioning relative to children with ASD, most notably in adaptive behavior and working memory. Therefore, ADHD may moderate the expression of components of the ASD cognitive and behavioral phenotype, but ASD+ADHD may not represent an etiologically distinct phenotype from ASD alone.
Journal of autism and developmental disorders, 2022 · doi:10.1002/aur.103