Enhanced motor noise in an autism subtype with poor motor skills.
Autistic kids fall into smooth or shaky hand-movement subtypes, and the shaky group shows much louder motor noise.
01Research in Context
What this study did
The team watched autistic kids reach for toys. They used motion cameras to track tiny hand jerks.
Computer math sorted the kids into two clear groups: smooth movers and shaky movers.
They also filmed typical kids and kids with other delays for comparison.
What they found
One group of autistic kids moved almost as smoothly as typical kids.
The other group looked much jerkier. Their hands wiggled with extra noise.
This "motor noise" gap was large and easy to see.
How this fits with other research
Kupzyk et al. (2011) studied twins and found clumsiness and autistic traits share genes. Mandelli’s work shows those genes may shape real-time hand control.
Lemons et al. (2015) split adults with autistic traits into social and detail groups. Mandelli does the same for kids, but uses hand motion instead of surveys.
Falligant et al. (2020) tried to reduce motor stereotypy with RIRD. Mandelli doesn’t treat movement; it simply shows that some kids are naturally shaky.
Why it matters
You now have a quick screen: watch a child reach. Jerky motion may flag the "low motor" subtype.
Pair this clue with other data to pick goals. Smooth movers might tackle fine-art crafts. Shaky movers may need warm-up trials or weighted cuffs.
Share the video with parents. A visual proof of "noisy arms" can justify OT or motor goals in the next IEP.
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02At a glance
03Original abstract
Motor difficulties are common in many, but not all, autistic individuals. These difficulties can co-occur with other problems, such as delays in language, intellectual, and adaptive functioning. Biological mechanisms underpinning such difficulties are less well understood. Poor motor skills tend to be more common in individuals carrying highly penetrant rare genetic mutations. Such mechanisms may have downstream consequences of altering neurophysiological excitation-inhibition balance and lead to enhanced behavioral motor noise. This study combined publicly available and in-house datasets of autistic (n = 156), typically-developing (TD, n = 149), and developmental coordination disorder (DCD, n = 23) children (age 3–16 years). Autism motor subtypes were identified based on patterns of motor abilities measured from the Movement Assessment Battery for Children 2nd edition. Stability-based relative clustering validation was used to identify autism motor subtypes and evaluate generalization accuracy in held-out data. Autism motor subtypes were tested for differences in motor noise, operationalized as the degree of dissimilarity between repeated motor kinematic trajectories recorded during a simple reach-to-drop task. Relatively ‘high’ (n = 87) versus ‘low’ (n = 69) autism motor subtypes could be detected and which generalize with 89% accuracy in held-out data. The relatively ‘low’ subtype was lower in general intellectual ability and older at age of independent walking, but did not differ in age at first words or autistic traits or symptomatology. Motor noise was considerably higher in the ‘low’ subtype compared to ‘high’ (Cohen’s d = 0.77) or TD children (Cohen’s d = 0.85), but similar between autism ‘high’ and TD children (Cohen’s d = 0.08). Enhanced motor noise in the ‘low’ subtype was also most pronounced during the feedforward phase of reaching actions. The sample size of this work is limited. Future work in larger samples along with independent replication is important. Motor noise was measured only on one specific motor task. Thus, a more comprehensive assessment of motor noise on many other motor tasks is needed. Autism can be split into at least two discrete motor subtypes that are characterized by differing levels of motor noise. This suggests that autism motor subtypes may be underpinned by different biological mechanisms. The online version contains supplementary material available at 10.1186/s13229-024-00618-0.
Molecular Autism, 2024 · doi:10.1186/s13229-024-00618-0