Facts & Statistics

“How prevalent is ASD? How have changes in diagnostic rates impacted our perception of Autism’s prevalence? Where are there gaps in our diagnosis of Autism?

Looking at statistics is a great way to get quantifiable answers to questions like these. Below, you can find a summary of some of the most recent statistics available on prevalence, diagnosis, intelligence, and employment for the Autistic population.”

Prevalence of ASD

A CDC report from the December 2021 Surveillance Summaries found that in the US in 2018, 1 in 44 children were identified with ASD by age 8. (CDC, 2021). 

The report above adds the following:

• The prevalence of ASD among 8-year-old children has increased from 1 in 150 (0.67% of the population) in 2002 to 1 in 54 (1.85%) in 2016.

• There has been a decrease in the proportion of Autistic children with intellectual disability from 50%  in 2002 to 33%  in 2016.

Reading these statistics, you may wonder why the prevalence of Autism diagnoses is increasing. Are rates of Autism in the population increasing?

This 2017 article in Scientific American sheds some light on this phenomenon. As the article points out, some of the seeming increase in Autism prevalence could reflect changing diagnostic definitions and criteria.

Public awareness of Autism is also increasing, so more people are seeking out diagnoses for their children or themselves. 

Nonetheless, there continue to be gaps in evaluations. The CDC reported that by age 8, 30% of children in the CDC study group who met the study’s criteria for ASD still did not have a formal ASD diagnosis.

(CDC, 2019)

That data only covers children “identified with ASD.” It is not uncommon for an ASD diagnosis to be missed entirely until adulthood.

The prevalence of ASD among adults in the US may be around 5,437,988 people, which is 2.21% of the population.

As the CDC explains, there are surveillance systems to gauge data for Autistic children, but not Autistic adults. As a result, there has been a major research gap. The estimate above is the first of its kind, made by the CDC in 2017.

A further breakdown in the data reveals that around 3.62% of adult men (4,357,667) in the US may be Autistic, and around 0.86% of adult women (1,080,322) in the US may be Autistic.

(CDC, 2020)

Diagnosis of ASD 

Adults who suspect they may be Autistic may pursue a diagnosis, but it can be a challenge. In particular, women who are Autistic may be overlooked. 

As the Frist Center for Autism and Innovation explains,

“Even from youth, the diagnostic tools used to identify autism are more likely to accurately identify males. That may be because these tools were largely developed by observation of boys and men with autism. Clinicians note that girls and women on the spectrum display more subtle signs of ASD … Therefore, only females with more pervasive and impactful difficulties may be easily identified by professionals.”

The ratio of diagnoses of Autism in boys versus girls is a ratio of about 4 to 1 (CDC, 2021).

The CDC notes that in the past, ASD diagnoses were more common among white children than in other ethnic groups. Based on data in 2018, however, this difference appears to have leveled out, except in certain locations. Rates of diagnosis are now roughly comparable among children identified as being white, black, Hispanic, Asian, or Pacific Islander. The CDC explains that this change likely is the result of improvements to outreach efforts (CDC, 2021).

Missed diagnoses are a serious concern from the Autistic community. Individuals who grow up without a diagnosis may struggle to understand some of the differences they note between themselves and their peers.

They also may not have access to valuable support services that could help them to navigate a successful path through education, work, and life.

So, it is great news that Autistic children who are members of minority communities are now more likely to get the support they need.

In the UK, data also points toward a rise in the rates of ASD diagnoses.

Hogrefe states that around 1-2% of the UK population is Autistic. This adds up to about 100,000 children and 1 million adults (Hogrefe, 2021).

In the same post, Hogrefe makes some interesting observations about how COVID-19 may have contributed to a rise in Autism referrals.

As parents spend more time in close proximity with their children under lockdown, they may be more likely to spot potential signs of Autism. Moreover, the increased stresses of everyday life might also exacerbate the challenges faced by Autistic individuals. This could be another reason to seek out diagnosis.

Intelligence

IQs among Autistic individuals span a wide range. The CDC reports that “among children aged 8 years with ASD who had data on cognitive ability”:

• 41.7% were in the average or higher range (IQ >85)
• 35.2% were considered to have an intellectual disability (IQ ≤70) 
• 23.1% were in the borderline range (IQ = 71–85) 

(CDC, 2021)

There are concerns that existing IQ tests may not provide an accurate assessment of intelligence in Autistic individuals. Standard IQ tests and subtests were created with a neurotypical neurotype in mind.

A post at Spectrum News paraphrases Tony Charman, professor of autism education at the University of London as explaining, “IQ scores generally relate to the ability to communicate or to adapt to daily life, but they are far from perfect indicators of cognitive, much less global, functioning.” (Spectrum News, 2011).

Other issues with IQ testing involve the nature of the testing itself. An Autistic person might be highly intelligent, yet have a difficult time with assessment instructions or the format of the testing.

Plus, for neurotypical persons taking IQ tests, various abilities and skills are clustered together. Scoring high in one area often predicts scoring high in others. But for Autistic persons, scoring high in one skill area may not be as predictive of scoring high in others (Indian J Psychol Med.).

Additionally, even if an Autistic person performs well on an IQ test, it is possible that they still have a hard time getting by in everyday life. Their parents, healthcare providers and teachers may assume they are able to function without assistance. In reality, some individuals may still need additional support.

There may also be situations where someone scores low on an IQ test, or cannot even complete an IQ test, and an assumption is made that this person has low intelligence. But they could be highly intelligent, but not in a way that standard IQ tests are able to accurately measure.

Employment Gaps

A frequently-cited 2011 article states, “Most studies indicate that 75-85% of adults with Asperger Syndrome do not hold a full-time job” (Autism Spectrum News, 2011). 

This situation does not appear to have improved over the years. UK data from the Office of National Statistics (ONS) in the UK in 2020 found that 78% of Autistic adults are unemployed (National Autistic Society, 2021).

2021 data from the US Bureau of Labor Statistics says that only 19.1% of all disabled persons are employed (Bureau of Labor Statistics, 2022).

Many Autistic individuals who are out of the workforce are highly skilled. Deficiencies in social support services combined with workplaces tailored to neurotypical individuals may account for some of the challenges Autistic persons face in this area of life.