By Emily Leclerc | Waisman Science Writer
Note: The Durkin lab uses identity first language in response to the growing preference for this type of language in the autism community. This article reflects that choice.
A new large-scale, population-based study from the lab of Waisman investigator Maureen Durkin, PhD, DrPH, professor of population health sciences and Evan and Marion Helfaer Professor of Public Health, reveals that motor delays may be a common yet underrecognized symptom in autistic children. The research found that 72% of the children included in the study met the criteria for motor delays.
Generally, when people think of autism, issues with motor skills do not come to mind. The most recognized symptoms are repetitive and restrictive behaviors and troubles with social communication. But this new research from Durkin and Olivia Pokoski, doctoral student in Durkin’s lab and first author of the paper, shows that motor delays may impact a large portion of the autism community. “There isn’t a lot of information about the actual prevalence of motor skill issues in autistic individuals and we hoped we could contribute to that knowledge base,” says Pokoski.
Motor delays are situations where an infant isn’t meeting some or all of their movement milestones in the expected timeframe, like sitting up, holding their head up, and walking. Case studies and small studies throughout the years have shown a higher prevalence of motor delays in individuals with autism, but the size and scope of the studies were typically not large enough to make more generalized inferences. “In order to tease out how common motor delays are in autism, you need a large sample that you can pull apart and examine all of the confounding factors. Having a population-based study like this one makes it more generalizable,” says Durkin.
Durkin and Pokoski’s new study, Prevalence of motor milestone delays in autistic children, which was published in the journal JAMA Pediatrics, found that 72% of individuals in their dataset diagnosed with autism met the criteria for having motor milestone delays. This indicates that motor delays could be a much more common phenomenon in autistic individuals than previously thought.
The dataset that Durkin and Pokoski used in this study is unique in several ways. Not only is it large –including 32,850 eight-year-old kids diagnosed with autism between 2000 and 2016 – but it covers a diverse enough cross-section of the population that it can be used to draw more generalized conclusions. “We really try to include everyone. There are people from all across income ranges, race, and other variables,” Pokoski says. Because this large dataset more accurately represents the population, it is much more likely to provide an accurate estimate of the prevalence of motor delays across all autistic kids in the U.S.
The data came from the Autism and Developmental Disabilities (ADDM) Network which is a Centers for Disease Control and Prevention (CDC) funded program that annually collects data on different disabilities across the U.S. to help better understand the conditions. Durkin runs the ADDM Network surveillance site in Wisconsin.
Interestingly, Durkin and Pokoski also found that kids who had motor delays were more likely to be diagnosed earlier than kids who did not. “Kids with motor delays were evaluated for autism eight months earlier and diagnosed three months earlier than kids without motor delays,” Pokoski says.
Currently, an autism diagnosis is almost entirely based on behavioral and mental symptoms. Those can be harder to catch in an infant. Motor delays often present in a more obvious way in young kids. “Motor skills in babies may be easier to see and parents could more accurately pinpoint when their child is crawling or walking,” Pokoski says. “Social skills can be a little more challenging because they are a bit more subjective.”
Durkin and Pokoski’s finding that motor delays may occur in almost three quarters of kids diagnosed with autism, could provide an important early indicator for autism. That could allow for earlier diagnoses and earlier access to interventions and therapies, which are almost always linked to better long-term outcomes for individuals. “Skills tend to build on each other so the earlier interventions start, the more skills people will be likely to gain and develop throughout their lifetime,” Pokoski says.
This study also adds evidence to the argument that motor delays might have a place in the Diagnostic and Statistical Manual of Mental Disorders’ (DSM) autism diagnosis criteria. “There has been some controversy in the literature about whether or not to note motor milestone delays in an autism diagnosis,” Durkin says. “The DSM is focused almost solely on mental and behavioral traits and is less concerned with physical attributes even though they may be important in autism.” Motor challenges are included as an associated feature but are not a prominent factor or specifier in a diagnosis.
With Durkin and Pokoski’s estimate of prevalence being so high, it gives more credence to the argument to add these physical symptoms to the DSM’s criteria list or specifier. And because motor delays are often noticed earlier than behavioral symptoms, it could aid in kids receiving earlier diagnoses and the benefits that come with that.