Infant muscle tone and childhood autistic traits: A longitudinal study in the general population.
A quick floppy-tone check at the 2-month visit gives a small but useful heads-up that a child may show more autistic-like behaviors by age six.
01Research in Context
What this study did
Doctors checked muscle tone in 2- to 5-month-old babies during routine visits. They scored how floppy or stiff each baby felt. Six years later they asked parents to fill out a short survey about the child's social and communication habits.
The team wanted to know if early muscle tone could hint at later autistic-like traits in everyday kids, not just those already flagged for autism.
What they found
Babies who felt a little floppy grew up to score slightly higher on the autism-trait survey. The link was small but real in a large group of typical families.
Low tone did not mean the child would get an autism diagnosis. It simply added one more early clue for watchers to note.
How this fits with other research
Ludyga et al. (2021) flipped the lens: in older kids with ASD, stronger muscles went hand-in-hand with better planning skills. Together the two papers draw a line from infant tone to childhood traits, then from youth strength to thinking skills.
Redquest et al. (2021) also watched infants and saw that fine-motor delays at 9–14 months predicted later autism likelihood. Low tone and fine-motor delay are different flags, but both tell us to keep watching movement milestones.
Mulder et al. (2020) found a seeming twist: babies who later receive an ASD diagnosis often start life with an “easy” temperament. That looks opposite to Fadila’s floppy signal. The difference is in what was measured: muscle tone is a body sign; temperament is mood and soothability. Both can coexist—an easy baby can still feel floppy—so the studies do not truly clash.
Why it matters
You can add a two-second muscle-tone check to your infant screening toolkit. Feel the shoulders and trunk during natural handling. If the baby feels floppy and you already see limited eye contact, mark the chart for closer follow-up. Share the finding with parents so they understand why you will check progress again at 12 and 24 months.
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02At a glance
03Original abstract
In a longitudinal population-based study of 2,905 children, we investigated if infants' neuromotor development was associated with autistic traits in childhood. Overall motor development and muscle tone were examined by trained research assistants with an adapted version of Touwen's Neurodevelopmental Examination between ages 2 and 5 months. Tone was assessed in several positions and items were scored as normal, low, or high tone. Parents rated their children's autistic traits with the Social Responsiveness Scale (SRS) and the Pervasive Developmental Problems (PDP) subscale of the Child Behavior Checklist at 6 years. We defined clinical PDP if scores were >98th percentile of the norm population. Diagnosis of autism spectrum disorder (ASD) was clinically confirmed in 30 children. We observed a modest association between overall neuromotor development in infants and autistic traits. Low muscle tone in infancy predicted autistic traits measured by SRS (adjusted beta = 0.05, 95% CI for B: 0.00-0.02, P = 0.01), and PDP (adjusted beta = 0.08, 95% CI for B: 0.04-0.10, P < 0.001). Similar results emerged for the association of low muscle tone and clinical PDP (adjusted OR = 1.36, 95% CI: 1.08-1.72, P = 0.01) at age 6 years. Results remained unchanged if adjusted for child intelligence. There was no association between high muscle tone and SRS or PDP. Exclusion of children with ASD diagnosis did not change the association. This large study showed a prospective association of infant muscle tone with autistic traits in childhood. Our findings suggest that early detection of low muscle tone might be a gateway to improve early diagnosis of ASD. Autism Res 2017, 10: 757-768. © 2017 International Society for Autism Research, Wiley Periodicals, Inc.
Autism research : official journal of the International Society for Autism Research, 2017 · doi:10.1002/aur.1739