Autism spectrum disorder (ASD) has surged in children in recent years, even among those who are just 4 years old.
According to data from the Autism and Developmental Disabilities Monitoring (ADDM) Network, the overall prevalence of ASD in 2020 was 21.5 per 1,000 children aged 4. This marks a 26% increase from 2018, when the prevalence was 17 per 1,000.
The numbers are not uniform across all regions, with California reporting the highest rate at 46.4 per 1,000, while Utah saw the lowest at 12.7 per 1,000. Stark gender and racial disparities also exist in ASD diagnoses.
Boys are diagnosed with autism more frequently than girls, with a prevalence of 32.3 per 1,000 compared to 10.4 per 1,000 for girls, whose ASD symptoms often differ from their male counterparts.
Overall, however, in 2020, 1 in 30, or 3.49%, of children ages 3 to 17 were diagnosed with autism — that’s about 33 per 1,000 individuals.
Shifting demographics: Autism rates higher in certain groups
Recent data reveals a significant shift in autism prevalence among different racial and ethnic groups. For the first time, the ADDM Network reported that white children aged 8 years have a lower prevalence of autism compared to their Black, Hispanic and Asian or Pacific Islander peers.
Specifically, the prevalence was 24.3 per 1,000 among white children, while it was 29.3 among Black children, 31.6 among Hispanic children and 33.4 among Asian or Pacific Islander children.
Another compelling aspect of the latest autism statistics is the nuanced relationship between socioeconomic status (SES) and autism prevalence. Unlike earlier years, where higher SES was strongly associated with increased autism diagnoses, the 2020 data shows a more complex picture.
In three out of the 11 ADDM Network sites — Arizona, New Jersey and Utah — children from lower-income households exhibited higher autism prevalence. When data from all sites were combined, there was a noticeable trend of lower autism prevalence in higher SES census tracts.
However, the differences across low, medium and high SES groups were relatively modest, ranging between 23 to 27.2 per 1,000 children.
Understanding when children are diagnosed with autism is important for ensuring they receive timely interventions. The 2020 ADDM Network data provides valuable insights into the age at which children receive their first autism diagnosis.
The median age of earliest known autism diagnosis was 49 months, with significant variations across states — from as early as 36 months in California to as late as 59 months in Minnesota.
Additionally, children diagnosed with ASD who also have an intellectual disability tend to receive their diagnoses earlier, with a median age of 43 months compared to 53 months for those without an intellectual disability.
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