Neurobehavioural Patterns in the Diagnosis of Autism Spectrum Disorder in Down Syndrome.

Background: Autism spectrum disorder (ASD) is common in Down syndrome (DS). There are no standardised screening/assessment tools for evaluating ASD in DS.

Methods: We utilised a novel validated questionnaire, the ND-PROM, to investigate differences in developmental skills and behaviours among children with DS only, ASD only and DS + ASD.

Results: Data analysis using ANOVA tests and post hoc t-tests revealed item-level differences between groups in domains specific to ASD (nonverbal communication, social-emotional understanding, social interaction, independent play, restrictive and repetitive behaviours and interests and sensory processes) and not specific to ASD (expressive language, receptive language, adaptive/toileting, challenging behaviours, mental health and impulse/ADHD).

Conclusion: ASD-specific symptoms best distinguished DS only and DS + ASD groups, while non-ASD symptoms best distinguished ASD only and DS + ASD groups. Items that best differentiate groups are presented.