Autism spectrum disorder symptoms among children enrolled in the Study to Explore Early Development (SEED).

The SEED project looked at preschoolers in four groups: autism, developmental delay with autism-like traits, developmental delay without those traits, and typical kids.

Doctors and psychologists scored each child on social, communication, and repetitive-behavior items.

The goal was to see if the groups looked different on paper, not to treat them.

Children with autism and kids with delays plus autism symptoms showed mild-to-severe risk on every measure.

Children with delays but no autism traits, and typical kids, scored in the low-risk range.

The four groups formed clear, separate pictures, backing the idea that autism has a distinct signature.

Fernell et al. (2010) saw the same messy mix in an earlier case series: only one in five preschoolers with autism looked "classic." SEED confirms that heterogeneity but shows you can still sort kids into clean risk bands if you measure carefully.

Dellapiazza et al. (2024) followed autistic children for three years and found symptom paths often shift. SEED’s snapshot is useful, but remember those risk levels can move; plan to re-assess.

Slaughter et al. (2014) used the same four-group design but counted tummy pain instead of autism traits. Both studies find the same pattern—ASD and DD-with-symptoms cluster together, separate from DD-alone and typical kids—showing the grouping holds across very different features.

You now have evidence that a short, well-chosen battery can tell you which preschoolers belong in the autism-risk lane and which do not. Use that to triage early, write clearer reports, and pick targets that match the child’s actual profile instead of guessing.