The structure of autism spectrum disorder symptoms in the general population at 18 months.
Autism traits already form the familiar three-factor shape by 18 months.
01Research in Context
What this study did
The team looked at 18-month-olds from the general population.
Parents filled out a 23-item autism checklist.
Stats grouped kids into symptom classes to see how autism traits cluster.
What they found
Three clear factors showed up: social, communication, and repetitive behaviors.
These factors sorted babies into four symptom profiles.
Even at 18 months, autism signs already line up like the DSM-5 model.
How this fits with other research
Sasson et al. (2022) used the same math on kids with Down syndrome years.
They also found three factors, but only three classes, not four.
The difference is age and diagnosis, not a true clash.
Fecteau et al. (2003) tracked the same three domains over years.
They showed social symptoms improve most, giving a growth backdrop to the 18-month map.
Why it matters
You can trust the classic three-domain model as early as 18 months.
Use brief parent checklists during toddler screenings.
If a child lands in the high-social-low-communication class, start social-communication targets first.
Want CEUs on This Topic?
The ABA Clubhouse has 60+ free CEUs — live every Wednesday. Ethics, supervision & clinical topics.
Join Free →Add a 23-item parent checklist to your 18-month intake and score the three domains.
02At a glance
03Original abstract
It is unclear whether symptoms of autism spectrum disorder (ASD) in young children in the population fit the three-factor structure of ASD as described in the DSM-IV, and cluster together in individual subjects. This study analysed questionnaire data on ASD symptoms filled in by mothers of 11,332 18-month-old children that was collected in the context of the Norwegian Mother and Child Cohort Study conducted by the Norwegian Institute of Public Health. Confirmatory Factor Analyses showed that the three-factor model had a significantly better fit then the two- and one-factor model of ASD symptoms. Latent class analysis revealed four homogeneous groups of children (classes) with different scores for Social Interaction and Communication at one hand and Stereotypies/Rigidity at the other hand.
Journal of autism and developmental disorders, 2013 · doi:10.1037/1082-989X.12.1.58