The rate of autism diagnoses has risen in recent years. Some people question whether autism is overdiagnosed in the United States.

The higher rate of diagnoses is partially due to broader diagnostic criteria and an increased awareness of the disorder. If this is the case, it means that the disorder isn’t being overdiagnosed in 2020. Rather, in the past, many cases of autism went undiagnosed.

The increased rates of autism mean that more children are getting access to treatment services earlier. Since early intervention is critical to successful treatment, some say that possible overdiagnosis is not necessarily a bad thing.

Rates of Autism Diagnosis in the United States

What are the rates of autism diagnosis?

In 2020, the Centers for Disease Control and Prevention released its biennial update of the estimated prevalence of autism spectrum disorder among American children. The figures in the update are based on an analysis of medical and school records (where available) of 8-year-old children, from 11 monitoring sites across the country, compiled in 2016.

Around 1 in every 54 children is diagnosed with autism spectrum disorder. In 2014, the estimate was 1 in 59, making this an almost 10% increase.

Autism tends to be much more common in boys, at a rate of 1 in every 34 boys. For girls, the rate lowers to 1 in 144, making boys four times more likely to be diagnosed with autism spectrum disorder than girls. However, this raises the possibility that girls on the autism spectrum are going undiagnosed and not receiving the therapy and care they need.

While autism is usually reliably diagnosed around age 2, most children in America are still only diagnosed when they are older than 4. Encouragingly, the number of children who were screened for any developmental disorder by age 3 increased from 74% to 84%, indicating progress toward earlier and more frequent and consistent screening.

Over 30% of children with autism have an intellectual disability, where their intelligence quotient is less than 70%. A quarter of kids with autism have borderline intelligence (an IQ of 71 to 85); 44% have IQ scores higher than 85, placing them in the average to above average range.

Gaps in Diagnosis Rates

Autism spectrum symptoms are found across every ethnic and socioeconomic demographic. Minority groups tend to be diagnosed later in life and less often, perhaps as a result of limited awareness of ASD and limited access to health care (for reasons of economics or culture).

Even different CDC monitoring sites may have conflicting standards. Colorado reported a low frequency of autism diagnosis at a rate of 1 in 76, while New Jersey’s rate was high at 1 in 32. The diagnosis and documentation of autism appear differently across communities.

Overall, the CDC report shows a continued increase in the rate of autism spectrum disorder in the United States.

For the first time, the CDC found no difference in the prevalence of autism diagnosis rates between Black children and white children, which suggests that barriers in access to screening and diagnosis may be coming down. However, there is still a gap in the prevalence of autism rates in Latinx children, suggesting that this group requires increased screening and intervention. While Black and white children had similar diagnosis rates, the CDC’s data found that Black and Latinx children with autism were evaluated at older ages than white children, suggesting more limited access to screening for these groups.

What’s Driving the Rates of Diagnosis?

Commenting on the CDC’s report, the president and CEO of Autism Speaks noted that the prevalence of 1 in 54 is a considerable change from the estimated prevalence rate of 1 in 166, back in 2005 when Autism Speaks was founded. She suggested that this is the result of increased and better screening, which lowers the age of diagnosis in minority populations and increases the chances of accessing therapy earlier in life.

While the CDC report was positively received, some autism advocates expressed concern that changing the criteria for autism may result in an overdiagnosis of autism spectrum disorder. Other experts counter that changing the criteria for autism means that the official diagnosis rates are catching up to the reality of autism occurring in more people and at an earlier age, allowing health care professionals to begin therapy sooner rather than later.

Considerably Overextended

A study carried out by researchers at the University of Montreal found evidence that suggests that more people with milder autism symptoms are being diagnosed with autism spectrum disorder. The differences between people diagnosed with autism and those who don’t have autism have decreased.

One of the authors of the study, (which was published in JAMA Psychiatry), also the chair of cognitive neuroscience in autism at the university, explained that prevalence rates are up by 15 times what they were 50 years ago, concluding that “the autism category has considerably overextended.” In the past, it would not be possible to have both attention deficit hyperactivity disorder and autism; now, that diagnosis can be made. This is the result of a number of neurogenetic and child psychiatry disorders that have “only a loose resemblance with autism” now being folded in under the broader category of an autism spectrum disorder.

This poses a dilemma for doctors. While there is justification for an autism diagnosis in cases that have both presentations, it muddies the waters when it comes to patients who have severe ADHD with heavy socialization problems. In the latter case, there is a concern that these patients will be diagnosed as autistic when they are in fact not.

Inclusive & Heterogeneous Population

The findings from the study echo other voices that raise the question of whether autism is being overdiagnosed in 2020. But it can also suggest that early detection of autism symptoms has led to an increase in the awareness of how varied the spectrum of autism can be, and more people with both milder or significant manifestations of autism are being properly accounted for.

The study noted that broadening the definition of autism “toward an inclusive and heterogenous population” runs the risk of reducing the ability to build effective and working models to better understand the true nature of autism and to devise appropriate therapies.

There is the further risk that broadening the definition of autism, and diagnosing more people with ASD, will overburden current autism therapy services.

Overdiagnosis vs. Better Diagnosis

Even as advocates for increasing the scope of autism diagnosis acknowledge that this will change the landscape of autism in the United States, they point out that as there is a greater awareness of ASD, and more research is conducted into the condition, it is inevitable that more autistic people will finally be identified and be given the therapy they need. It is not so much a case of overdiagnosis, they say, but better diagnosis.

Educating individuals, parents, and communities about the early warning signs of autism means little if the definition of autism remains tightly controlled and closed. Early intervention and diagnosis will do more good for more people than the alternative.

Others contend that the core characteristics of autism, such as repetitive behavior and socio-emotional and language limitations, have not changed; therefore, autism is not being overdiagnosed. Instead, treatment providers are identifying milder manifestations of autism spectrum disorder, and ensuring that people with these milder manifestations are still getting help.

Distinct but Related Conditions

Recent changes to the diagnostic criteria for autism have not weakened the definition of autism, some experts say. Instead, the changes have allowed health care professionals to better understand the underlying processes for distinct, but related, conditions that share symptoms with autism. This gives them a wider understanding of the many presentations of autism and other conditions that overlap.

Even as the rate of autism diagnoses has increased, more people are getting more accurate diagnoses earlier in life, meaning that more people who actually have autism are getting the necessary intervention and therapy that they need to control their disorder.

Changes in Autism Diagnostic Criteria

How has the criteria for autism diagnosis changed? Between 1966 and 2019, the autism prevalence rate increased from less than 0.05% at age 8 to 1.47%, and that figure is expected to rise.

The 2013 revision of the Diagnostic and Statistical Manual of Mental Disorders, published by the American Psychiatric Association, combined previously separate diagnoses of autistic disorder, Asperger’s syndrome, childhood disintegrative disorder, and pervasive developmental disorder – not otherwise specified into the widely used title of autism spectrum disorder. This, says the Social Psychiatry and Psychiatric Epidemiology journal, “maximizes diagnostic sensitivity and specificity [of autism] in preschool children.”

This especially speaks to populations where autism tends to go undiagnosed. Many people believe that girls cannot have autism, but the expanding definition of autism can encourage parents of autistic girls to change this view.

Minority groups might resist the thought of a member of a particular culture or community being autistic (leading to “wide underrepresentation”) because of stigma associated with mental health disorders in general. People in low-income communities might not recognize the signs of autism. Indeed, the PLOS ONE journal reported that “the prevalence of ASD [...] is more likely to be higher in areas with the highest level of [socioeconomic] deprivation.”

In both of the latter cases, opening the diagnostic door might lead to a better understanding of what autism is and how widespread it can be.

Diagnosis Lost

But that pendulum swings both ways. In 2016, researchers at the University of Washington authored a study that was published in the Autism journal that looked at a group of people who had been diagnosed with autism. The researchers concluded that 9% of those people were erroneously diagnosed.

If the criteria for autism is expanding, the researchers concluded, then so should the criteria for reanalysis and reevaluation.

Is Autism Being Overdiagnosed?

The debate, says Psych Central, is a controversial one. Autism is a complicated medical condition that has defied many past attempts to treat it. Other disorders, like attention deficit hyperactivity disorder, have well-established pharmacological therapies to treat them; autism does not. Furthermore, the widening of the autism spectrum means that a person with a milder, high-functioning form of autism can have symptoms that look very different from a person who is completely nonverbal and nonresponsive.

This has led to anti-vaccination activists claiming that mandatory vaccinations of children have led to an “epidemic” of autism diagnoses, a view that is widely discredited by health care professionals. Studies have repeatedly debunked this theory, but it still persists on social media.

Questions and criticisms remain. An opinion piece in The Guardian suggested that the autism rights movement to raise awareness for neurodiversity “ignores those with debilitating severe autism,” which renders the diagnostic term of autism too broad to have any meaning.

However, as Scientific American points out, the understanding of autism has been in a constant state of evolution since the term was first used to describe the condition in 1943. Since then, as more has been understood about the disorder — and as more questions have been raised — researchers and experts have regularly tweaked the diagnostic criteria.

The most recent reevaluation of that criteria is, in that context, not surprising. But the backlash and concern about overdiagnosing perhaps speaks to the sensationalism, politicization, and continuing reappraisal of the true nature of autism.

References

We're Overdiagnosing Kids With Autism, but Maybe That's Not Such a Bad Thing. Parents.com.

Prevalence of Autism Spectrum Disorder Among Children Aged 8 Years — Autism and Developmental Disabilities Monitoring Network, 11 Sites, United States, 2016. (March 2020). Centers for Disease Control and Prevention.

CDC Estimate on Autism Prevalence Increases by Nearly 10 Percent, to 1 In 54 Children in the U.S. (March 2020). Autism Speaks.

Temporal Changes in Effect Sizes of Studies Comparing Individuals With and Without Autism. (2019). JAMA Psychiatry.

Social Functioning Difficulties In ADHD: Association With PDD Risk. (February 2010). Clinical Child Psychology And Psychiatry.

Closing the Gap: Creating More Equity in Diagnosis of Autism Spectrum Disorder. (February 2020). PolicyLab at Children's Hospital of Philadelphia.

DSM-5 Criteria tor Autism Spectrum Disorder Maximizes Diagnostic Sensitivity and Specificity In Preschool Children. (August 2019). Social Psychiatry and Psychiatric Epidemiology.

Why It’s Harder for Girls to Get an Autism Diagnosis. (June 2019). The Mighty.

Minorities Widely Underrepresented in Autism Diagnoses. (May 2018). Science Daily.

Socioeconomic Disparities and Prevalence of Autism Spectrum Disorders and Intellectual Disability. (2016). PLOS One.

Diagnosis Lost: Differences Between Children Who Had And Who Currently Have an Autism Spectrum Disorder Diagnosis. (October 2015). Autism.

Why No One Is Talking About the Possible Overdiagnosis of Autism. (July 2018). Psych Central.

Is the 'Autism Epidemic' Real? Researchers Say Over-diagnosis to Blame for Spike in Number of Cases. (August 2019). National Post.

What Is Autism? How the Term Became Too Broad to Have Meaning Anymore. (August 2019). The Guardian.

The Real Reasons Autism Rates Are Up in the U.S. (March 2017). Scientific American.

You Can Blame CNN (and the News Media) if Childhood Vaccinations Go Down. (September 2015). The Washington Post.

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