Down Syndrome and Autism

Traditional thinking held that autism was rare in people with Down syndrome, but that is far from the case. In fact, it is estimated that autism in individuals with Down syndrome is 10-25 times more common than in the typical population. At the Down Syndrome Resource Foundation, our prevalence rate is in line with these studies, with approximately 12% of our students having a dual diagnosis. However, this diagnosis often comes much later than it would for an otherwise typical child.

In one study of subjects with a dual diagnosis, the mean age of autism diagnosis was 14.4 years – this despite the fact that, as with other children, autistic symptoms are present much earlier in life (rarely do they emerge in kids after the age of three, whether or not they have Down syndrome).

This delayed diagnosis creates many problems. Clearly, children with a dual diagnosis are at a real disadvantage in their development and education, even relative to children with only one of the disabilities. Even more problematic are the faulty expectations that may be placed on the child where the autism has gone undetected. As one study concluded, “inconsistent or poor social relating in a child expected to be ‘charming’ or ‘outgoing’ may create some frustration for all concerned and may lead to a poor fit between the child and the expectations in the environment.”

Parents, many of whom report that the symptoms associated with autism are more difficult to deal with than Down syndrome, can feel that their child’s slower development is their fault; that they haven’t done enough to help their child with Down syndrome. They notice that other children with Down syndrome are more advanced and exhibiting less severe behavioural problems, leading to feelings of frustration and inadequacy. These parents need extra support, but they may not feel like they fit in well with other Down syndrome families.

This diagram illustrates characteristics commonly associated with Down syndrome, autism, and both:

Below is a collection of resources to help parents, caregivers and professionals support a person with a dual diagnosis of Down syndrome and autism.

The LowDOWN Podcast - Dual Diagnosis: The Down Syndrome-Autism Connection (Oct. 28, 2020)

Putting the Pieces Together: The Down Syndrome-Autism Intersection

16 Actions with Objects by 16 Months

16 Gestures by 16 Months

A Closer Look at Social Communication Difficulties of Children with Autism Spectrum Disorder

“Tuning In” to Others: How Young Children Develop Theory of Mind

A List of Apps for Social Skills and Autism Spectrum Disorders

Links to ASD Websites:

First Words Project
Act Community Training
Autism BC
BC Autism Assessment Network dg
The Down Syndrome - Autism Connection df
Pacific Autism Family Network
Teach Me To Talk
Hanen’s Autism Corner
What is Autism Spectrum Disorder and What Should Parents and Educators Know?

Down Syndrome Resource Foundation
1409 Sperling Avenue, Burnaby
British Columbia, Canada
V5B 4J8

Fax: +1 604 431 9248
Phone: +1 604 444 3773