Is Autism Overdiagnosed? Prevalence, Criteria Changes and Debates

Autism is being identified more now than in the past, and some are wondering if it is being overdiagnosed. We take a closer look at the investigation.

There was a time when autism was something you only heard about. There’s a good chance you know an autistic person, or there may be one or two in your child’s class at school. You or your child may be autistic.

Growth in autism awareness and new diagnostic criteria are two examples of factors that may explain the increased rates of diagnosis.

Still, there are those who question whether there is an autism epidemic or whether mental health professionals are overdiagnosing autism.

Data from the Centers for Disease Control and Prevention (CDC) show an increasing trend in the prevalence of autism between the years 2000 and 2018.

These figures, as shown in the table below, make it clear that the number of diagnoses of autism is increasing, but the cause is still under debate.

Some people believe that diagnostic rates are higher than necessary. Others believe that current rates include autistic people who may have been missed in the past.

1. A New Understanding of Autism

A Meta-analysis 2019 including data from 27,723 people, it was found that official differences between autistic and allistic (non-autistic) people have diminished over time. This can influence the diagnosis process of autism.

The change from a narrow description of autism to a broader one could interfere with building mechanistic models of autism, according to the study.

A mechanical model is an example of something. Without a clear sample, some people fear that the autism diagnosis might be less meaningful. This can lead to a broader definition of autism, resulting in more frequent diagnoses.

A 2021 study identified four scenarios where an autism diagnosis may not be helpful:

  1. when the diagnostic tools cause ambiguities about the diagnosis
  2. when the person has a subclinical (less obvious) presentation
  3. When Early Signs of Autism Fade During Development
  4. when other conditions are present

Because the diagnosis of autism is still based on behavior, it can be difficult for clinicians to tell the difference between autistic people, neurotypical people with autistic traits, and people with other neurological or psychiatric conditions.

2. More support is available to help children thrive

In some situations, child funding is set up to support autism more than other diagnoses. Examples include specialized schools and teacher-pupil ratios. An autism diagnosis can also provide financial assistance.

Some therapies, such as applied behavior analysis, are only available in certain states and with certain insurance companies if the child is diagnosed with autism.

It is possible that more children will be referred for autism screenings so that they can access this support.

3. Diagnosis Can Be Rushed

The advantage of early diagnosis is that it can provide helpful support for autistic children. In well-intentioned attempts to access this support, children may receive definitive autism diagnoses too early.

Instead, preliminary diagnoses, including support for follow-up assessments, may be more appropriate to avoid misdiagnosis.

4. Autism may have been underdiagnosed in the past

It is also possible that the current diagnosis figures give a more accurate picture of the autism figures. Milder versions of autism that were previously missed are now more likely to be identified.

It’s easier to mask a milder version of something. Masking is a person’s ability to hide features of a condition, such as ADHD masking or autism masking. The purpose of masking is to make it easier to fit into typical society.

Masking may still interfere with autism identification, as indicated in a 2019 study that looked at the use of compensatory strategies in autism. The study recognized that some autistic adults hide autistic traits well enough to avoid diagnosis.

At first glance, masking may seem like a useful coping strategy until you consider that it can be exhausting, stressful, and contribute to mental health issues.

Changes in the diagnostic process have contributed to the increased autism rates.

In the 1940s, autism was first identified as occurring in children. Now experts recognize autism in people of all ages.

The current version of the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5) has reclassified several previously separate conditions:

  • autistic disorder
  • Asperger’s Syndrome
  • Disintegrative Disorder in Children
  • pervasive developmental disorder not otherwise specified (PDD-NOS)

Now they exist together under the umbrella of “autism spectrum disorder.”

A 2015 study in Denmark revealed that changed reporting practices could be responsible for as much as 60% of the increase in autism diagnoses in children born between 1980 and 1991.

It is possible for autism to be misdiagnosed.

An allistic person may be mistakenly identified as autistic. Alternatively, a person may be diagnosed with something else if they are actually autistic.

It is also possible that an autistic person who needs minimal support will need more than one assessment before their autism is diagnosed. They can mask their differences so well that they don’t seem to meet the diagnostic criteria.

However, this does not mean that their differences are insignificant or that they would not appreciate support.

Features that are sometimes confused with autism include:

  • hearing problems
  • speech delays
  • Development delays
  • giftedness
  • early reading
  • specialized interests
  • sensory processing differences

Sometimes features of autism show up with other psychological diagnoses, such as:

Lead poisoning can also mimic the developmental delays that sometimes occur with autism.

Doctors used to believe that the signs of autism were part of a schizophrenia spectrum disorder. Sensory and communicative differences are two examples of characteristics that were misunderstood.

Now clinicians understand that autism is a separate cognitive profile and occurs on a spectrum. In some people the signs are obvious, while in others they may be subtle and not immediately recognizable.

Specialists diagnose autism by assessing a person’s behavior.

They begin by comparing developmental milestones with those of normally developing children using parent forms and questionnaires.

If there are enough signs to indicate that autism may be present, they will perform more tests, such as:

  • Autism Diagnostic Interview-Revised (ADI-R). The ADI-R is a parent interview to evaluate children’s past and present behaviors that may indicate autism.
  • Autism Diagnostic Observation Schedule (ADOS-2)† This is an age-specific test with modules that assess characteristics such as repetitive behavior and communication differences.
  • Rating Scale for Childhood Autism, Second Edition (CARS-2). This 15-question test can help diagnosticians distinguish the presence of autism from other conditions.

Clinicians also perform tests to check for other problems that may cause symptoms, such as differences in hearing, vision, or motor skills.

Autism exists on a spectrum. This means that no two autistic people are exactly alike.

Some people may show obvious signs that they are autistic. They may have noticeable support needs, such as communication differences, and exhibit behaviors that allistic people do not understand.

Other autistic people may look more like icebergs, with only a few signs visible. Meanwhile, their skill at masking keeps other autism traits hidden beneath the surface. Social confusion, difficulty with change, and auditory processing difficulties are some examples.

As awareness of autism increases and diagnostic procedures adapt, more autistic people can be identified and helpful services offered. Greater availability of these services could also increase the rate at which children are referred for assessments.

To learn more about autism, visit Psych Central’s Autism Resources Hub.