Most people have heard of Autism Spectrum Disorder (ASD) and Down syndrome (DS) but many do not know that a child can have both. Today we discuss this dual diagnosis in an interview with providers and parents of children with both ASD and DS.
Lynn: What do we know about the genetics of ASD and DS? Are kids with DS any more at risk for ASD than others? How common is the dual diagnosis?
Raphael Bernier, PhD: You know, Lynn, I think what gets tricky when we talk about the genetics of ASD and DS is that the DS diagnosis is made (or can be confirmed) by genetic testing which reveals the presence of the third chromosome 21. In contrast, the ASD diagnosis is made strictly on behavioral observation. There are currently no genetic tests for ASD.
However, we’ve made massive gains in our understanding of the genetics of ASD in just the past 10 years so this does provide some insight into the relationship between ASD and DS. For example, a couple of genes that keep popping up as ASD risk genes are located on chromosome 21 in the DS critical region suggesting a genetic connection between ASD and DS. Importantly, these children with ASD and disruptions to these genes on chromosome 21 do not demonstrate the physical features of DS.
Rates of ASD in individuals with DS appear to be higher than would be expected given the population prevalence of ASD. But, there is some variability in those rates reported in the literature, which speaks to the difficulties of making a dual diagnosis.
For many children with DS, impairments from intellectual disability can make an ASD diagnosis difficult to determine. If families are concerned that their child with DS is showing significant social communication impairments, seeing a professional with expertise in ASD is definitely a wise course of action.
Lynn: We know that DS is diagnosed in-utero or at birth, while ASD is diagnosed later. Do very young children with DS display the same red flags in development as those with ASD alone? How if at all, is their presentation different?
Dr. Bernier: That’s a great question. Many children with DS may show some of the red flags for ASD, not because they have ASD, but because many red flags may be due to intellectual impairments associated with DS.
For example, one red flag for autism is a failure to use single words by 16 months or short, two word phrases by 24 months. Children with DS may show language delays such as these, but not have ASD.
Another red flag for autism is failure to use gestures, such as pointing or waving goodbye. In contrast to the similarities in language delay, we might expect a young child with DS (who does NOT have ASD) to use nonverbal behaviors, such as pointing or eye contact, to compensate for difficulties in language use.
In DS, social communication may be delayed, but as cognitive abilities improve, we’d expect to see these social-communication behaviors also improve, while in ASD we’d see a significant lagging behind in social communication skills relative to cognitive abilities.
Lynn: There is a belief, perhaps a stereotype, that children with DS have good interest in socialization and/or good social skills while we know that a hallmark of ASD is difficulty with socialization. Does having DS mitigate some of the challenges of ASD?
Dr. Bernier: Well, that’s another good question. Social ability is a dimension that ranges from significant impairment to significant strength. We see variability in social skills for children with DS just like with everyone so it’s unlikely that having DS provides a protective factor for social skills.
However there are examples of genetic disorders marked by increased social interest (although not necessarily improved social skills), such as Williams syndrome. So, again, I’d say, if a child with DS is showing challenges in social communication, it may be appropriate for that child to be evaluated for a diagnosis of ASD.
Lynn: What are some of the unique aspects of working with children with ASD and DS?
Noa Hannah, PhD, CCC-SLP, BCBA-D: Children with ASD and DS have a unique makeup. Intellectual impairment associated with DS can range from mild to profound and that is the same for those with dual diagnoses. While each child is different, what I see most in my practice (children who are non-verbal) is that the strong-willed piece of the DS characteristics can be emphasized by the rigidity of thought, a characteristic of ASD. In my experience I’ve seen social strengths in children with DS and while this might be a mitigating factor, in my clinical practice, that increased social interest sometimes presents as increased disruptive behaviors for attention.
Jo Ristow, MS, CCC-SLP: I find that in working with kids with ASD and DS, tapping into their motivation is key, and their spiritedness and gumption can be a real strength when it is channeled into functional communication.
Lynn: As a parent of a child with a dual diagnosis of ASD and DS, how did it come about that you or someone else had concerns that your child might have ASD?
Phillip: Our eight year old daughter with ASD and DS was adopted from an orphanage at age five. She was malnourished and had significant physical and developmental delays. Once she made gains physically, some of the features of autism became apparent such as repetitive mannerisms (rocking, flicking beads and string in front of eyes), taking us by the hand and leading us to what she wanted, and inconsistent eye contact. We were relieved to get the ASD diagnosis because the behavior we were seeing wasn’t fitting what we knew about DS. We want others to know that children can have both and that if they have any concerns, to check it out.
Sara: My son was in a developmental preschool and staff there mentioned to me some concerns for ASD. They recommended he be evaluated and he got the diagnosis at age three. I’m glad we did because it helped us to understand him better and get the services he needed.
We’d like to thank our parents and providers for sharing their perspective on the dual diagnoses of ASD and DS.