During the 1970’s it was reported that 1 in 2000 children were diagnosed with ASD, by 2000 it was 1 in 150 and the latest report by the CDC in the US report that 1 in 44 children have ASD. We have started to gather statistics on the subject to give you a clearer picture.
According to the latest report by the CDC (based on data collected up to 2018), ASD prevalence in the USA has increased significantly:
- 1 in 44 (or 2.3%) of children in the US were identified with ASD using estimates from CDC’s Autism and Developmental Disabilities Monitoring (ADDM) Network
- These stats were based on eight-year-olds living in 11 ADDM Network sites in the United States
- The 2021 prevalence estimate from data collected in 2018 is roughly 241% higher than estimates from 2000
- The last estimate, reported in 2020, showed 1 in 54 kids identified with ASD. A mere year later the reported estimate increased to 1 in 44
Gender, race and socioeconomic factors
- CDC data estimates a male to female ratio of 4:1 in autism, but other research suggests a ratio closer to 3:1
- Close to 6% of autistic children have some form of gender dysphoria (We will do a follow up article on this)
- Autism occurs in all socioeconomic groups. In contrast to previous years’ ADDM data, socioeconomic status (as measured by neighborhood-level mean household income) was not consistently associated with autism prevalence
- CDC data suggests prevalence is similar across racial and ethnic groups
- Examples include: California at 3.9%, Missouri at 1.7%, South Korea at 2.84%, France at 0.36%, and Qatar at 1.14%
- Many developing countries do not have reliable autism statistics due to a lack of resources. This means most autism research is from affluent, English-speaking countries
Autism prevalence rates in adults
Many parents discover their own neurodivergence when seeking a diagnosis for their child
- An estimated 2.2% of adults in the US are autistic, according to a CDC report
- Consistent with estimates of ASD in children, California has the greatest (estimated) number of adults with ASD in the states surveyed in the US
- Prevalence is higher in men than women
- These adult statistics highlight the fact that autism is a lifelong neurodevelopmental condition
Do areas with higher prevalence rates have parents who are better educated and more aware of autism? Alternatively, are these areas, with higher prevalence rates, more accepting of neurodivergence, creating an environment where seeking diagnosis and intervention is easier with less stigma? We need more research but autism prevalence does seem to be influenced by:
- Autism education, awareness, and acceptance
- Better diagnostic practices
- Changes in diagnostic criteria
Causes and risk factors
- Autism has a strong genetic component as demonstrated by twin studies
- A child has an approximately 19% higher risk of autism if an older sibling is on the spectrum
- A growing body of evidence investigating maternal infection, drug use, and age (there is also evidence linking advanced paternal age to an increased risk) as potential causes of autism
- Health complications during pregnancy and in childbirth may raise a child’s autism risk significantly, a baby experiencing complications both during and before birth may have a 44% increased risk of autism
Autism Parenting Magazine has done a great job here at summarizing the data reported in the USA.
What about South Africa?
Even though there is much less data available about the prevalence of ASD in South Africa, there have been some recent studies on the subject. In 2015 it was reported in a study published in the South African Journal of Childhood Education that the prevalence of children with ASD in South Africa is still unknown. This study, focusing on learners at a school for children with Autism Spectrum Disorders in Gauteng, estimated that there are about 270 000 people in SA with Autism with 5000 newly diagnosed each year. It further observes that:
- There was an 8.2% increase in the number of children presenting with ASD features attending a developmental clinic in Gauteng over the period 1996-2005
- It is also not clear whether the increase in the prevalence of ASD in South Africa is related to a heightened awareness of ASD among professionals and parents, or to the broadening of diagnostic criteria since 2000
Probably the most comprehensive recent study in South Africa is this one, by UCT's Centre for Autism Research in Africa, even though it was only a statistical study based on data from the WCED. Published in 2020, it looked at the prevalence of Autism in 1 million school children in the Western Cape. Some findings of the study were:
- From a population of 1,154,353 children attending schools in the province, a total of 940 children with a diagnosis of autism spectrum disorder were identified
- That represents a rate of 0.08% or 1 in 1200 children
- The male: female ratio was 5.5:1
- A higher proportion of children with autism spectrum disorder were from White racial groups and English-speaking homes
- 89% of children with autism spectrum disorder were in “Special Schools” and only 10% were in Mainstream Schools.
- Most of the children (83%) attended schools in the City of Cape Town and only 17% in rural areas.
- Co-occurring intellectual disability was reported in 22.2% of the population, attention-deficit/hyperactivity disorder in 2.6% and epilepsy in 0.7%.
- Data showed a 76.03% increase in autism spectrum disorder in schools between 2012 and 2016, with an average increase of 15.18% per year.
- Findings suggested an under-representation of autism spectrum disorder in schools and an under-identification of co-occurring conditions.
The full study is behind a paywall, but hopefully some more information can become available.
We will add more statistical information over the next weeks, including
- Statistics about the impact, treatment and families of children with ASD
- Gender dysmorphia and ASD