Identifying motor milestone delay can lead to earlier autism diagnosis | Image Credit: © vejaa - © vejaa - stock.adobe.com.

The earlier identification of motor milestone delays could lead to an earlier evaluation for and diagnosis of autism, thus leading to better intervention and developmental outcomes, according to a study published in JAMA Pediatrics.¹

Motor impairments and autism

"Prior literature has explored the prevalence of motor impairments in autistic individuals, but estimates come from clinical, convenience, or small samples, limiting generalizability," stated the study's authors, led by Olivia Pokoski, MPH, of the Department of Population Health Sciences at the University of Wisconsin-Madison School of Medicine and Public Health. "Better understanding of the frequency of motor milestone delays in autistic individuals could improve early identification and subsequently lead to earlier intervention and better developmental outcomes," they added.

Multiple studies, noted the investigators, have determined that motor impairments become more pronounced with age, making intervention a priority in early childhood to mitigate progression.² Cognitive impairment has been previously associated with increased motor challenges among individuals with autism, suggesting a co-occurring diagnosis of intellectual disability (ID) could either account for, or exacerbate motor difficulties.¹

"Differences in motor milestone delay frequencies across key characteristics were tested using likelihood ratio χ² tests for nominal variables and Mantel-Haenszel χ² tests for ordinal variables," wrote the investigators. "The population prevalence and 95% confidence intervals of autism with and without motor milestone delays were calculated per 1000 children aged 8 years overall and by sociodemographic characteristics, surveillance site, and year."¹

Prevalence ratio (PR) and 95% confidence intervals were calculated in order to compare autism prevalence with and without motor milestone delays.

Study design and participants

The investigative team sought to determine motor milestone delay prevalence in a population-based sample of 8-year-old children with autism. In a cross-sectional design, the study was conducted using Autism and Developmental Disabilities Monitoring (ADDM) Network data between surveillance years 2000 and 2016. These date were population based and were pulled from 17 sites in the United States.

With a binary indicator of motor milestone delays that were documented in health or education records as the primary exposure, the primary endpoint was prevalence of motor milestone delays in the study population. This association was evaluated using linear regression, with covariates of study site, surveillance year, the number of autism discriminators, intellectual disability, child sex, and child race and ethnicity.

In all, 23,481 children met the criteria for motor milestone delays, of which 18.2% were female. Those with motor milestone delays were evaluated for autism "significantly earlier" than children without delays (mean age, 43.65 months; 95% CI, 43.38-43.91 vs mean age, 51.64 months; 95% CI, 51.22-52.06). Following the stratifying by co-occurrence of ID, children with motor milestone delays were evaluated for autism earlier than those without delays, no matter of ID.

Autism prevalence with motor milestone delays

Autism prevalence with motor milestone delays was 8.59 per 1000 children aged 8 years, indicating a 2.5 ratio of autistic children with motor milestone delays for every autistic child without delays (95% CI, 8.48-8.70). Children with milestone delays had more autism discriminators than those without delays, and autism prevalence with motor milestone delays and co-occurring ID was "more than 2-fold that of autism with motor milestone delays without ID," the investigative team wrote.

Earlier autism evaluation

Regarding evaluation for autism, those with milestone delays had a mean age of 43.65 months (95% CI, 43.38-43.91) for earliest evaluation compared to 51.64 months (95% CI, 51.22-52.06) for children without milestone delays (mean difference, −7.99; 95% CI, −8.50 to −7.49).

Conclusion

Overall, findings revealed that a higher proportion of children with autism had a history of motor milestone delays. These delays were associated with an earlier age at autism evaluation and diagnosis.

"Although motor delays are not exclusive to autism, their presence could serve as an important indicator to prompt clinicians to screen for autism, potentially facilitating timely diagnosis and interventions to improve developmental outcomes," the authors wrote. "Future research is needed to understand the role of motor skills in early autism identification and the potential implications of including motor assessments in diagnostic protocols for [autism spectrum disorder]," they concluded.

References:

1. Pokoski OM, Furnier SM, Gangnon RE, et al. Prevalence of Motor Milestone Delays in Autistic Children. JAMA Pediatr. Published online April 14, 2025. doi:10.1001/jamapediatrics.2025.0216

2. Licari MK, Alvares GA, Varcin K, et al. Prevalence of motor difficulties in autism spectrum disorder: analysis of a population-based cohort. Autism Res. 2020;13(2):298-306. doi:10.1002/aur.2230