More and more people are being diagnosed with autism. Increased awareness and screening efforts may reveal why autism is becoming more common.

It might seem like autism spectrum disorder (ASD) is more prevalent nowadays than it was 10 or 20 years ago.

Statistics from health organizations suggest that autism spectrum disorder diagnoses are on the rise. This doesn’t necessarily mean that autism itself is becoming more common. Although this might be the case, it could also be that more people are receiving autism diagnoses.

While many autistic people may have gone undiagnosed before, factors like increased awareness might help more people receive a diagnosis.

As of 2018, the Centers for Disease Control (CDC) estimated that about 1 in 44 eight-year-olds in the US met the diagnostic criteria for autism spectrum disorder. In 2000, the first year that they began keeping records on autism, that number was 1 in 150.

The World Health Organization (WHO), on the other hand, estimates that about 1 in 100 children have autism. This estimation is based on global statistics.

But the WHO notes that this number varies across studies and could be higher. In some countries, there is little-to-no data about the prevalence of autism.

How accurate are these estimations? It’s hard to say. The CDC’s estimation is based on school and medical records, which might miss children with no records, or children with less obvious signs.

While there are statistics on the prevalence of autism, it varies from study to study, and there’s no global medical consensus on how common autism really is.

Broadened criteria for diagnosis

Part of the reason why more people are diagnosed with autism as of late is that the definition of autism has expanded.

The term ‘infantile autism’ was first coined in 1943 by Leo Kanner, who used it to describe children that seemed socially withdrawn. Since then, the clinical definition of autism has changed.

In the US, clinicians have used the Diagnostic and Statistical Manual of Mental Disorders (DSM) to diagnose mental and developmental conditions for the past few decades. Every new edition of the DSM includes updated definitions of conditions.

Here’s how the DSM’s definition of autism has changed over the years:

  • 1980: autism first appeared in the DSM. In order to receive a diagnosis, a child needed to meet 6 criteria.
  • 1987: a new edition of the DSM expanded the diagnostic criteria. In order to meet the diagnosis, a child needed to meet 8 of 16 criteria.
  • 1994: the DSM broadened the definition of autism by including Asperger syndrome.
  • 2013: the DSM-5 categorized autism, Asperger syndrome, and pervasive developmental disorder not otherwise specified (PDD-NOS) into a single diagnosis, autism spectrum disorder.

While the previous edition of the DSM didn’t allow people to be diagnosed with autism and attention deficit hyperactivity disorder (ADHD), the DSM-5-TR version does.

Given that the CDC estimates that 14% of autistic children had ADHD in 2016, it’s possible that many people weren’t diagnosed with autism because they also had ADHD.

The DSM-5-TR is used in the United States and not globally. But like the latest version of the DSM, the 11th edition of the International Classification of Diseases (ICD-11), which is developed by the WHO, has expanded its definition of autism.

Now, the ICD-11 includes Asperger’s Syndrome, Childhood Disintegrative Disorder (CDD), and other developmental disorders within the category of autism.

Autism might seem more common now than it did in the 80s. But it’s important to remember that the definition of autism has changed a great deal in the past forty-odd years.

Increased screening efforts

In the US, more children are being screened for autism than before.

In 2006, the American Academy of Pediatrics (AAP) recommended screening all children for autism during routine pediatrician visits at 18 and 24 months of age. Today, they recommend all children are screened for developmental delays at 9, 18, and 30 months old

It’s not clear how much this recommendation is adhered to, but it might’ve led to more diagnoses in young children, especially those with less obvious signs.

Increased awareness

A 2021 study found that there was a 787% exponential increase in the number of people who were diagnosed with autism between 1998 and 2018 in the UK.

The groups that experienced the steepest increases in autism diagnoses were women and adults. The authors say that this suggests that growing awareness could have led to an increase in diagnoses.

Autism awareness is increasing. Because of this, parents and teachers might notice signs of autism that they might’ve otherwise missed. This might lead them to seek diagnoses for their children and students.

Likewise, while autism was previously thought of as something that affects children, more people are now aware of adult autism. Adults might learn more about autism, find that they fit the diagnostic criteria, and look for a diagnosis themselves.

Pre-term baby survival rates

According to 2021 research, children who were born prematurely are more likely to be diagnosed with autism. And the earlier they’re born, the more likely they are to be autistic.

Medical advances mean pre-term newborns around the world are more likely to survive the neonatal period. It’s possible that this has led to more autistic babies surviving into childhood.

Other factors

You might be under the perception that autism is more common because we’re simply talking about it more.

We live in an age of information where it’s easier than ever to look up the signs of autism. Social media means that autistic people can actively talk about their experiences to an audience that might not otherwise have access to that information.

Although there’s still a stigma attached to autism, it’s arguably becoming less stigmatized in certain circles, so people might feel more comfortable sharing that they have autism.

There is no blood test or brain scan that is used to diagnose autism. Instead, autism is diagnosed based on observations of behavior.

Using observation to diagnose autism can have challenges. Because autism is a spectrum, the signs differ from one person to the next and it doesn’t always look the same. Additionally, a clinician’s biases can affect how they interpret their patient’s behavior.

According to the CDC, boys are four times more likely to be diagnosed with autism than girls. Some experts suggest that girls aren’t necessarily less likely to have autism — they’re less likely to be diagnosed with it.

Compared to men and boys with autism, women and girls with autism tend to:

Women and girls might be less likely to be diagnosed because they are less likely to express the behavior people typically associate with autism.

Additionally, gender bias might play a role in preventing autistic women and girls from being diagnosed. If parents and teachers assume girls are unlikely to be autistic, they’re less likely to suggest screenings.

Most diagnostic questionnaires for autism are based on childhood development. As such, it can be difficult to be diagnosed with autism as an adult — but it’s not impossible. But your doctor will probably ask about your developmental history.

Learn more about how autism is diagnosed.

Autism diagnoses are on the rise. This doesn’t necessarily mean autism itself is increasing, although that may be the case. It’s more likely that increased awareness and broadened diagnostic criteria mean that more people are being diagnosed.

But there are still biases in diagnosis. Autistic women and girls are less likely to be diagnosed, and it can be difficult to find a diagnosis as an adult.

An autism diagnosis can help you obtain accommodations and find community support. If you think you’re autistic, or if you think your child or loved one is autistic, consider speaking with a healthcare professional about a screening.