Characteristics Associated with Autism Spectrum Disorder Risk in Individuals with Down Syndrome.

Channell et al. (2019) looked at people with Down syndrome. They asked which traits flag a higher chance of also meeting autism criteria.

They checked IQ scores, daily-living skills, and problem behaviors. Then they compared these scores to autism symptom checklists.

Lower IQ and weaker self-care skills went hand-in-hand with more autism features. More tantrums, self-harm, or repetitive actions also pointed to higher autism risk.

Cook et al. (2021) extends this picture. They show that kids who have both Down syndrome and autism speak in shorter, simpler phrases than kids with Down syndrome alone.

Porter et al. (2008) seems to disagree. In adults with intellectual disability, autism did not add extra mental-health risk once ability level and Down syndrome were counted. The gap is age and method: Moore studied children and used direct skill tests, while A et al. tracked adult service records.

Schaaf et al. (2015) back up Moore on behavior: across teens with autism, harsher autism symptoms predict more self-injury, just as Moore saw in the Down-syndrome group.

If you assess a child with Down syndrome, do not assume delays are "just the DS." Check adaptive scores and note any rising problem behaviors. When both are low, add an autism screener to your plan and prepare for speech and behavior goals that are more intense.