TOPLINE:

Repetitive motor behaviors (RMBs) such as hand flapping and rocking occur in more than one third of toddlers who do not meet diagnostic criteria for autism spectrum disorder (ASD), with higher rates observed in children with other developmental concerns (ODC). Among nonautistic children, those with RMBs demonstrate slightly lower communication scores and higher autism-related symptomatology, though group means remain within average ranges.

METHODOLOGY:

• Researchers conducted a cohort study assessing RMBs in a community sample of 679 toddlers in the US at 24 and 36 months of age between 2020 and 2024.
• Participants were recruited via hospital records, state birth records, and social media, with caregivers completing online screening measures at 6, 9, 12, 18, and 24 months.
• A total of 679 children who participated in both 24- and 36-month tele-assessments were included, with evaluations conducted via Zoom by examiners unaware of screening status.
• RMB status was determined using item 5 of the TELE-ASD-PEDS (TAP), which assesses unusual or repetitive body movements, with scores dichotomized as no RMB vs possible or clear RMB.
• Outcome groups included 65 participants with ASD and 614 nonautistic participants, with the nonautistic group further divided into 104 with ODC and 510 with no developmental concerns (NDC).

TAKEAWAY:

• A total of 36% of nonautistic children demonstrated RMB at 24 and/or 36 months of age, with RMBs present in 55% of the ODC group compared with 33% of the NDC group (χ²[3], 24.08; P < .001).
• Nonautistic participants with RMBs had lower communication scores at 24 months (F[3, 610], 5.87; P < .001; partial η², 0.03) and higher TAP scores minus the RMB item at both 24 months (F[3, 610], 17.70; P < .001; partial η², 0.08) and 36 months (F[3, 610], 8.29; P < .001; partial η², 0.04).
• The RMB-both group had higher M-CHAT-R scores compared with the RMB-negative group (F[3, 603], 5.53; P < .001; partial η², 0.03), though all group means remained well below the screen-positive cutoff of 3.
• No differences in RMB group distribution were observed based on sex, ethnicity, race, maternal education, or household income (P > .14 for all) in either the ASD or non-ASD groups.

IN PRACTICE:

“RMBs are not uncommon in 24- to 36-month-old children who do not meet diagnostic criteria for autism. Among nonautistic children, RMBs are most likely to occur in those with other developmental challenges but are also present in some typically developing children,” wrote the authors of the study.

SOURCE:

The study was led by Monique Moore Hill, MA, Department of Psychiatry and Behavioral Sciences, MIND Institute, University of California-Davis. It was published online in the Journal of Pediatrics.

LIMITATIONS:

Evaluations were conducted mostly in children who screened positive on screening measures, though the study used very broad screening criteria resulting in evaluation of almost 50% of the initial community sample, which is much higher than typical screen-positive rates. The measure used to identify RMBs, the TAP, is relatively brief at approximately 20-30 minutes via telehealth, and a lengthier or in-person evaluation may have identified RMBs in more children, providing a conservative bias that would underestimate the rate of RMBs in nonautistic toddlers. RMB status was determined based on a single item that did not differentiate specific RMBs such as hand flapping vs toe walking, limiting the ability to quantify the frequency of individual RMBs. Different methods were used to assess communication at each age, with an interview at 24 months vs a questionnaire at 36 months, which may account for differing results, and children may have received intervention for language delays between assessments that could affect associations.

DISCLOSURES:

The National Institutes of Health provided grant R01 MH121344 to support this study, awarded to Sally Ozonoff, PhD. The funding organization had no involvement in study design, data collection, analysis, interpretation, report writing, or the decision to submit the manuscript for publication. All authors reported no relevant financial or nonfinancial interests to disclose.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.