The prevalence of autism spectrum disorder (ASD) has increased from one in 44 children in 2018 to one in 36 in 2020, according to the latest CDC surveillance data released in the March 24 Morbidity and Mortality Weekly Report (MMWR).
The updated numbers result from 2020 data retrieved from the Autism and Developmental Disabilities Monitoring (ADDM) network, an active surveillance system with 11 monitoring sites across the United States.
The ADDM used information from children born in 2012 who lived in surveillance areas during 2020 and reviewed developmental evaluations and records from educational and medical service providers to gather the data. Data included in the report came from sites in Arizona, Arkansas, California, Georgia, Maryland, Minnesota, Missouri, New Jersey, Tennessee, Utah, and Wisconsin.
For 2020, the overall ASD prevalence was 27.6 per 1,000 (one in 36) children aged eight years. That number ranged from 23.1 per 1,000 in Maryland to 44.9 per 1,000 in California. Moreover, Wisconsin and Missouri showed the most significant relative changes in autism prevalence.
The surveillance data also indicated that the prevalence of ASD was lower among white children than among other racial and ethnic groups — which differs from past observations.
However, autistic Black children were still more likely than white children with ASD to have a co-occurring intellectual disability. Overall, among the 4,165 autistic children with cognitive ability data, almost 38% had an intellectual disability.
The report also found that the age of the earliest known ASD diagnosis ranged from 36 months in California to 59 months in Minnesota.
According to the report, "the continued increase among children identified with ASD, particularly among non-white children and girls, highlights the need for enhanced infrastructure to provide equitable diagnostic, treatment, and support services for all children with ASD."
Why is autism increasing?
During the past 20 years, the number of children identified with autism has increased exponentially. For example, in 2000, one in 150 children were identified with autism. In 2018, that number increased to one in 44. And now, the latest numbers of one in 36 shows that ASD continues to rise.
Still, reports indicate that autism rates might be even higher, especially in metropolitan areas.
Some sources say that genetics, interactions between genes and environmental factors, problems with metabolism, or immune system issues may play a role in the development of autism and its increasing prevalence.
However, according to the CDC, these increasing autism numbers are likely due to improvements in identifying ASD, particularly for children in groups that have less access or face greater barriers to obtaining services.