Motor Circuit Anatomy in Children with Autism Spectrum Disorder With or Without Attention Deficit Hyperactivity Disorder.
Extra gray matter in sensorimotor cortex explains why many kids with ASD move clumsily, especially when ADHD rides along.
01Research in Context
What this study did
Mahajan et al. (2016) scanned school-age kids with autism. Some kids also had ADHD. The team measured gray-matter volume in sensorimotor brain areas.
They compared three groups: ASD only, ASD plus ADHD, and typical kids. The goal was to see if extra brain tissue links to motor skill scores.
What they found
Kids with ASD showed overgrowth in sensorimotor cortices. The overgrowth pattern differed when ADHD was also present.
More volume matched worse motor skills. The study ties brain structure to real-world clumsiness.
How this fits with other research
Provost et al. (2007) first showed that almost every toddler with ASD has motor delays. Rajneesh now shows the brain side of that story years later.
Storch et al. (2012) looked at the same kids and found normal routine MRIs. The clash is only on the surface: regular scans miss tiny volume changes that special software can catch.
Goulardins et al. (2013) proved the trouble is in movement execution, not planning. Rajneesh’s overgrowth sits in the exact execution hubs, closing the loop.
Why it matters
When a child with ASD struggles to catch a ball, the issue may be real brain overgrowth, not lack of practice. Check for ADHD co-diagnosis; it changes the picture. Use fine motor tests, not just eyeball norms, and plan extra execution drills rather than planning drills.
Want CEUs on This Topic?
The ABA Clubhouse has 60+ free CEUs — live every Wednesday. Ethics, supervision & clinical topics.
Join Free →Add a quick finger-tapping or bead-threading probe to your session and note if ADHD co-diagnosis predicts slower speed.
02At a glance
03Original abstract
This study examined the morphology of frontal-parietal regions relevant to motor functions in children with autism spectrum disorder (ASD) with or without attention deficit hyperactivity disorder (ADHD). We also explored its associations with autism severity and motor skills, and the impact of comorbid ADHD on these associations. Participants included 126 school-age children: 30 had ASD only, 33 had ASD with ADHD, and 63 were typically developing. High resolution 3T MPRAGE images were acquired to examine the cortical morphology (gray matter volume, GMV, surface area, SA, and cortical thickness, CT) in three regions of interest (ROI): precentral gyrus (M1), postcentral gyrus (S1), and inferior parietal cortex (IPC). Children with ASD showed abnormal increases in GMV and SA in all three ROIs: (a) increased GMV in S1 bilaterally and in right M1 was specific to children with ASD without ADHD; (b) all children with ASD (with or without ADHD) showed increases in the left IPC SA. Furthermore, on measures of motor function, impaired praxis was associated with increased GMV in right S1 in the ASD group with ADHD. Children with ASD with ADHD showed a positive relationship between bilateral S1 GMV and manual dexterity, whereas children with ASD without ADHD showed a negative relationship. Our findings suggest that (a) ASD is associated with abnormal morphology of cortical circuits crucial to motor control and learning; (b) anomalous overgrowth of these regions, particularly S1, may contribute to impaired motor skill development, and (c) functional and morphological differences are apparent between children with ASD with or without ADHD.
Autism research : official journal of the International Society for Autism Research, 2016 · doi:10.1523/JNEUROSCI.2257-10.2010