Trends Over Time in the Prevalence of Autism by Adaptive and Intellectual Functioning Levels

Area of Science:

• Public Health
• Developmental Pediatrics
• Autism Spectrum Disorder Epidemiology

Background:

• Autism spectrum disorder (ASD) affects a diverse population with varying needs.
• Public health surveillance data on adaptive functioning can inform population-level support needs.
• Understanding trends in autism prevalence by adaptive functioning and co-occurring intellectual disability (ID) is crucial.

Purpose of the Study:

• To analyze trends in autism prevalence from 2000 to 2016.
• To examine autism prevalence by adaptive functioning levels and co-occurrence of ID.
• To describe changes in the population prevalence of autism phenotypes.

Main Methods:

• Utilized data from the Autism and Developmental Disabilities Monitoring Network (2000-2016).
• Abstracted adaptive behavior and cognitive scores from health and educational records.
• Estimated prevalence of autism per 1000 8-year-old children across four adaptive challenge levels and by ID co-occurrence.

Main Results:

• Autism prevalence with mild, borderline, or no adaptive challenges increased from 5.1 to 17.6 per 1000 children (2000-2016).
• Prevalence of autism with moderate to profound challenges slightly decreased from 1.5 to 1.2 per 1000 children.
• The increase in prevalence was more pronounced for autism without co-occurring ID, confined to milder phenotypes.

Conclusions:

• The rise in autism prevalence is linked to milder phenotypes, suggesting enhanced identification of these cases.
• Improved access to therapies may also contribute to observed trends in adaptive functioning.
• Continued monitoring of autism prevalence and adaptive functioning is essential for public health planning.