By Emily Leclerc | Waisman Science Writer
At a Glance:
- Diagnosing autism in an individual with Down syndrome can be hard because the two can have overlapping symptoms. This often results in later and less frequent diagnoses which can prevent access to early interventions and supports.
- A new paper from the lab of Waisman investigator Audra Sterling investigated what developmental markers could be indicators of autism in someone with Down syndrome.
- Fewer words produced, less use of gestures to communicate, and struggles with visual perception and fine motor skills were all associated with higher levels of autistic traits. Executive function skills were not associated with higher levels of autistic traits.
- This work may contribute to making diagnosing autism in Down syndrome easier. Clearer paths to diagnosis lead to earlier and more accurate diagnoses which better helps kids get the interventions and supports that they need.
Down syndrome, a neurodevelopmental condition caused by a triplicated 21st chromosome, often presents with co-occurring developmental conditions such as autism. But diagnosing autism in someone with Down syndrome can be difficult as they have overlapping symptoms. New research from the lab of Waisman investigator Audra Sterling, PhD, professor of communication sciences and disorders at UW-Madison, found that early differences in gesture use, the amount of words spoken, visual processing, and fine motor skills may be linked to increased autistic traits in children with Down syndrome. The hope is that this work can provide clearer indicators of autism to help make diagnoses less complicated.
Autism is a developmental condition characterized by difficulties with social communication and interaction, and restricted or repetitive behaviors, interests, or activities. Down syndrome can share some of these symptoms, especially during early development. “Sometimes certain characteristics of autism can be covered up by different parts of Down syndrome. That makes it hard to parcel out what is autism and what is Down syndrome,” says Tiffany Chavers Edgar, PhD, postdoctoral fellow in Sterling’s lab and first author on their new paper. This leads to later and less frequent autism diagnoses which can prevent access to early interventions and potentially needed supports.
There are also no established criteria for specifically diagnosing autism in individuals with other developmental conditions. “There aren’t really any autism diagnostic measures that are for individuals with other developmental disabilities. There’s nothing standardized for Down syndrome and autism, for example,” says Chavers Edgar.
The two conditions have wide variability in how they present and impact a person making it hard to decipher how the two conditions interact. That variability and symptom overlap can make it difficult for a clinician to determine if autism is truly present.
The researchers decided to investigate what developmental markers in children with Down syndrome could be indicators of autism-related traits. Their new paper, which was published in the journal Behavioral Sciences, found several developmental areas where changes were associated with increased autistic traits.
Language was the first developmental area the research team looked at. Both Down syndrome and autism have documented impacts on language development. They found significant associations with the number of words produced and the use of gestures. A reduced utilization of gestures and fewer words produced were highly associated with more autistic traits.
Gestures are an important form of nonverbal communication used by children and can often be a bridge to speech. Their use can be indicators of social-communication development and potentially delayed language. the study found that children with Down syndrome who engaged in less gestures were scored as having higher levels of autistic traits. This suggests that even early changes in nonverbal communication could be potential markers of autism-related behaviors.
While the study did find that fewer words produced was significantly associated with more autistic traits, this finding is more complicated. Research has shown that children with autism and children with Down syndrome often struggle with language development and tend to produce fewer words than typically developing kids. Children with autism tend to have lower social motivation and struggle with social reciprocity whereas coordinating the motor and cognitive skills needed for language can be difficult for kids with Down syndrome. Chavers Edgar says that more work needs to be done to determine if this association is just an area where Down syndrome and autism overlap or if there are more specific markers for individuals with both Down syndrome and autism.
They then looked at the developmental areas of visual perception skills and fine motor skills. Lower scores in visual processing ability and fine motor skills were significantly associated with increased levels of autistic traits. Both visual reception and fine motor skills have been connected to the development of social and communication skills as they support sustained attention, problem-solving skills, imitation, object exploration, and making gestures. Struggles in these areas could exacerbate other autistic traits in someone with Down syndrome, leading to the connection that Chavers Edgar found.
The last area she investigated was executive function. Executive functioning skills are related to planning, focus, memory and task management and include things like working memory, impulse control, and someone’s adaptability to change. The study did not find a significant association between executive functioning skills and autistic traits. She says a potential theory is that the kids included in the study, who ranged from ages two to five, were too young to have established executive functioning skills. These skills are only just starting to emerge at these ages and tend to be difficult to study in young kids.
“There is a lot of variability in language and developmental skills like fine motor and visual reception, and how it contributes to autism traits and Down syndrome. This work, in general, underscores the need for early, multi-domain assessment approaches to support accurate identification and tailored intervention for young children with Down syndrome,” says Chavers Edgar.
Language development, visual processing, and fine motor skills have the potential to be more distinct indicators of autism in individuals with Down syndrome. But it comes with the important caveat that this was a small and preliminary study. Further investigation is needed to start more clearly defining markers of autism in Down syndrome but this new research provides important future research directions.
Moving forward, Chavers Edgar hopes to expand this research into a longer-term study. The data used in this research was from one time point, which provides valuable insight, but doesn’t capture change over time. Developing a longitudinal study that tracks development would provide a more in-depth look at what markers are the strongest indicators for autism in Down syndrome.
The hope for this work is that it will help make diagnosing autism in Down syndrome easier. Clearer paths to diagnosis lead to earlier and more accurate diagnoses which better helps kids get the interventions and supports that they need.
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