Is There an Autism Epidemic?
- Kaitlyn Boudreault
- May 13
- 12 min read
The prevalence of autism in Canada has been steadily on the rise since the early 2000s, when researchers began to track autism with regional projects.
In 2018, the National Autism Spectrum Disorder Surveillance System (NASS), released by the Public Health Agency of Canada (PHAC), showed that these trends continued.
In fact, prevalence estimates of autism in children and youth went from 1 in 714 in 2000–2001 to 1 in 44 in 2023–2024.
These rising numbers have caused widespread public concern, with some people suggesting that there may be an ‘autism epidemic.’
But that’s not exactly what is happening. So what is happening?
The bulk of the increase in autism diagnoses can be attributed to improved awareness, broader definitions, and better access to identification and support.
At Blue Sky Learning, we offer support through neurodiversity-affirming therapists in Ontario, Canada, as well as international neurodivergent coaches.
Whether you are newly diagnosed, self-identified, or supporting a neurodivergent loved one, understanding neurodiversity-affirming care can make a meaningful difference.
In this section of our neurodivergent blog, we will explore why the increase in autism isn’t an epidemic and what is really responsible for the rise in prevalence.
Autism, clinically known as autism spectrum disorder, is a neurodevelopmental difference and form of neurodivergence that causes changes in the ways autistic people think, regulate, and experience the world.
Autistic traits can present as differences in communication, sensory processing, emotional regulation, learning, and social interaction. Autistic individuals may also engage in repetitive behaviours, known as “stimming.”
The word ‘spectrum’ reflects that all autistic individuals experience different traits along with varying severity levels. No two autistic people are the same, and if you have met one autistic person, you have only met one autistic individual.
Some may require significant daily support, while others may not be identified until adolescence or adulthood due to more subtle traits or masking behaviours (hiding autistic traits).
Are Autism Diagnosis Rates Actually Increasing?
Yes, on paper, the diagnostic rates of autism have increased over the past two decades globally.
In Canada, the rates increased from 0.14% to 2.25% between 2000–2001 and 2023-2024.
In addition, according to researchers at the Johns Hopkins Bloomberg School of Public Health, autism diagnoses have increased by roughly 300% over the past 20 years.
However, public health and epidemiological research consistently show that this increase does not mean that more people are suddenly becoming autistic.
Instead, prevalence has risen due to changes in identification, not a sudden surge in new cases or vaccines. Higher diagnosis rates do not automatically mean higher incidence.
A Deeper History: How Autism Diagnosis Has Evolved Over Time
To understand how the prevalence of autism has increased over the past several decades, we can look at how autism has been defined historically.
Early Conceptualizations (1940s–1960s)
In 1943, Leo Kanner first described autism as “early infantile autism.” He focused on children who experienced social withdrawal and communication challenges.
At this time, autism was not really recognized, unless there was a severe presentation, and it was considered rare. If someone was identified as having “early infantile autism,” they were institutionalized in many cases.
DSM-III (1980): Autism Formal Diagnosis
In the 1980s, autism was formally recognized within the DSM-III. The criteria still focused on a narrow childhood presentation of autism.
DSM-III-R and DSM-IV (1987–1994)
The DSM-III-R and DSM-IV were developed in 1987 and 1994, respectively, and resulted in the broadening of the diagnosis of autism.
For instance, the symptom thresholds for autism were reduced, and the age of onset for symptoms was relaxed.
During this time, “Asperger’s syndrome’ was also introduced as a separate diagnosis from autism, and pervasive developmental disorders became an umbrella category in the DSM where both autism and “Asperger’s” were listed under.
DSM-5 (2013): Autism Spectrum Disorder Unified
In 2013, the DSM-5 consolidated multiple diagnoses, including autism, Asperger’s syndrome, and pervasive developmental disorder not otherwise specified, under one category, known as autism spectrum disorder.
Why Are Autism Diagnoses Increasing?
There isn’t a specific reason for the rates of autism. But researchers have found that some overlapping factors may be contributing to the increase in autistic diagnoses.
1. Broader Diagnostic Criteria
Before 2013, when the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) was published, autism was divided into several separate diagnostic categories.
Autism was divided under the umbrella of “pervasive developmental disorders,” which included autistic spectrum disorder, Asperger’s syndrome, and pervasive developmental disorder–not otherwise specified (PDD-NOS).
Back then, individuals who would now be diagnosed as autistic may have previously received a different diagnosis depending on factors such as speech development, support needs, and clinician interpretation.
For example, some individuals were diagnosed with Asperger’s syndrome if they did not have significant language delays. Others may have received a PDD-NOS diagnosis when they showed some autistic traits but did not fully meet the narrower criteria used at the time.
Since 2013, these separate diagnoses have been consolidated under one diagnosis: Autism Spectrum Disorder (ASD).
The shift to including these conditions all under autism spectrum disorder reflects research that shows that autism exists as a broad spectrum of experiences and support needs, rather than several different conditions.
As a result, many individuals who may not have qualified under older, narrower definitions are now more accurately identified as autistic.
2. The Increase in Co-Occurring Autism + ADHD Diagnosis
Another change in diagnostic criteria that may explain the rise in autism diagnoses involves ADHD.
Before 2013, clinicians were not usually permitted to diagnose someone as being autistic and having ADHD. The DSM criteria, at the time, excluded autistic people from receiving a diagnosis of ADHD and vice versa.
If someone displayed traits of both, one diagnosis was usually prioritized while the other was excluded or overlooked.
Due to this, there was a significant underidentification of autistic individuals.
Since 2013, the DSM has allowed for autism to be diagnosed alongside ADHD, and the co-occurrence of these two conditions is strong.
Many autistic individuals also experience differences in attention, impulsivity, executive functioning, hyperactivity, or emotional regulation. Approximately 50-70% of autistic people have ADHD.
Individuals with ADHD who couldn’t be diagnosed as autistic in the past now can, which has increased the diagnostic rate of autism.
3. Increased Awareness, Screening, and Recognition
Over the past two decades, there has been an increase in the understanding of autism.
The developmental screening for autism is also far more common now within pediatric healthcare, educational systems, and mental health settings than in the past.
Many health providers are receiving additional training on the early signs of autism.
As a result, autistic traits are now being recognized earlier.
The general public also understands more about how autism presents. When the traits are identified early, children are more likely to be referred for comprehensive autism assessments and support services sooner than in the past.
For example, as schools have become more informed about autism, more students are being referred for psychoeducational or developmental assessments.
This increase in early identification extends across different population groups.
Historically, autism research and diagnostic models primarily focused on cis straight white boys who presented with more externally visible traits and higher support needs.
However, researchers and clinicians are becoming increasingly aware of how autism may present differently in AFAB (assigned female at birth) individuals, intellectually gifted individuals, and people who tend to engage in masking behaviours.
Now that researchers understand autism more, this broader understanding has caused many previously overlooked individuals to receive more accurate identification and support.
4. Increase in Late-Diagnosed Autism
Many adults grew up during periods when diagnostic criteria were narrower, and the awareness of autism was limited and based on stereotypes.
Some individuals were overlooked and didn’t get diagnosed with autism because they performed well academically, tended to mask their difficulties, or were misdiagnosed or written off as having anxiety, depression, personality disorders, obsessive-compulsive disorder (OCD), or ADHD instead.
The increase in public awareness of how autism presents across people has led many autistic adults to recognize themselves within the autistic experiences.
This increased awareness did not cause autism but improved recognition, identification, and access to diagnosis.
For individuals who were already autistic but may previously have been misunderstood, misdiagnosed, or entirely missed by older systems, they now have a diagnosis for their experiences. Society also includes these individuals in the prevalence of autism.
5. Diagnostic Substitution
Diagnostic substitution occurs when individuals who previously received one diagnosis may now be more accurately identified under a different diagnosis.
For example, some individuals may have previously been misdiagnosed with intellectual disabilities, anxiety, language disorders, depression, or personality disorders. Clinicians may have failed to recognize the underlying autistic profile contributing to these experiences.
The rates of misdiagnosis were especially common among AFAB individuals, BIPOC individuals, and those whose autistic traits did not match outdated stereotypes or narrow diagnostic expectations.
As diagnostic practices improve, clinicians have developed a more nuanced understanding of autism. As a result, many of these individuals who were previously misdiagnosed have now begun to receive autism diagnoses, either instead of or alongside previous diagnoses.
In other words, some of the increase in autism prevalence reflects a change in how individuals are classified diagnostically rather than a sudden increase in the number of autistic people themselves.
Because of diagnostic substitution, rising autism statistics should not automatically be interpreted as evidence of an “autism epidemic.” Instead, they often reflect improved recognition, broader diagnostic frameworks, changing clinical practices, and a growing understanding of the diversity of autistic experiences across the lifespan.
6. Improved Recognition in Underdiagnosed Groups
Historically, autism research, screening tools, and diagnostic criteria have been developed to focus primarily on studies of white, cisgender boys and those with more externally visible autistic traits.
Clinicians expected that autism would present as an obvious social difference, visibly repetitive behaviours, speech delays, or externalized behaviours.
Individuals who did not fit into this narrow population were overlooked, misunderstood, or misdiagnosed.
Today, research has expanded, and professionals have a more nuanced understanding of how autism appears across different groups, including:
Girls and women
Racialized communities
Gender-diverse individuals
Adults who masked traits in childhood
For example, many autistic girls and AFAB individuals are socialized from a young age and tend to mimic peers, suppress differences, and engage in masking to avoid social exclusion. They tend to internalize autistic traits, which can show as anxiety, perfectionism, people-pleasing, eating disorders, burnout, or chronic emotional exhaustion.
Similarly, BIPOC individuals have faced barriers to seeking autism diagnoses due to systemic inequities, cultural biases in the healthcare system, language barriers, and disparities in medical resources. BIPOC children have often been diagnosed later than white peers or misidentified with behavioural or emotional disorders instead of autism.
There is also growing recognition of the overlap between autism and gender and sexual orientation diversity. Many autistic individuals identify as transgender, nonbinary, gender-diverse, or part of the 2SLGBTQIA+ community. Increased awareness of this intersection has encouraged more affirming and inclusive assessment practices that better recognize the diversity of autistic experiences.
As diagnostic systems become more equitable and inclusive, prevalence rates naturally increase because more autistic individuals are finally being accurately identified. This does not mean autism is suddenly “appearing” more frequently. Rather, it reflects a growing ability to recognize autism across a wider range of identities, presentations, and lived experiences than was previously possible
7. Access to Services and Support
In Canada and the United States, an official autism diagnosis is often required to access supports, including educational accommodations, therapy services, disability funding, workplace supports, government programs, or insurance-covered interventions.
Due to this, some individuals have no choice but to seek a formal diagnosis if they want to seek formal support. The diagnosis functions as a gateway to practical resources that help autistic individuals navigate daily life more effectively.
For example, within educational settings, a formal autism diagnosis may be needed for students to access individualized education plans (IEPs). Without documented identification, some students may struggle to receive the support they need despite experiencing significant challenges.
In some provinces and regions, autism-specific funding programs or disability services are tied directly to diagnostic eligibility criteria.
Importantly, increased demand for assessments does not necessarily indicate that autism itself is becoming more common. Rather, it reflects the reality that support systems often require formal identification before individuals can receive accommodations or services.
8. How Autism Prevalence is Actually Measured
Understanding autism surveillance methods can help to interpret autism statistics.
Some surveillance systems, such as the CDC’s Autism and Developmental Disabilities Monitoring (ADDM) Network, tend to collect data from school and medical records.
They use these records to review documented developmental patterns and apply standardized diagnostic criteria retrospectively. They also estimate the prevalence based on population samples.
Therefore, researchers aren’t really directly testing every child, but they identify autism indicators in existing records.
There are limitations in this method because not all children have equal access to their school report card records or to a diagnosis, and some regions of the world have better screening systems than others. As a result, low support needs or masked presentations may be missed within this data.
This means prevalence estimates reflect identification rates, not absolute biological incidence.
Since surveillance methods have increased over the years and there has been an increase in access to diagnosis for groups that were previously misdiagnosed, the rate of autism has increased.
This method for estimating prevalence is still not perfect, and therefore, the estimates are likely still lower than what is the actual number of autistic cases. Because of this, you should likely still expect an increase in autism prevalence as surveillance methods continue to improve.
Why Do Autism Rates Vary by Region?
These prevalence differences reflect service availability and access to healthcare services, public awareness campaigns, school-based screening programs, and cultural differences around developmental differences.
The rates of autism are likely the same globally, but it is the difference in those being diagnosed that differs due to those reasons.
So, Is It an Autism Epidemic?
No, the word “epidemic” would imply that there is a sudden and rapid increase in the number of cases of a disease.
However, autism is not a disease, so a rise in the cases of autism can’t be classified as an epidemic.
The framing of autism as an epidemic also does not match what research shows. Autism is not spreading as an illness, but we are instead seeing an increase in the prevalence of autism due to several reasons, including, but not limited to:
Improved identification
Expanded diagnostic understanding
Greater social acceptance
Increased access to assessment tools
It is believed that autism has always been present at similar rates; however, we are simply getting better at seeing it. As Johns Hopkins University has said, the rise of autism prevalence is understood best through a reflection of changing systems and understanding, rather than as an epidemic.
Related: Debunking Myths About Autism
Myth vs. Fact: Autism “Epidemic” Claims
MYTH: Autism is rapidly increasing like a disease outbreak.
FACT: Autism is not contagious or spreading. Increased diagnosis reflects improved detection systems.
MYTH: Something in the environment is causing more autism.
FACT: No environmental factor has been identified as a primary driver of increased prevalence.
MYTH: Autism used to be rare.
FACT: Autism likely existed at similar rates historically, but was underdiagnosed or misclassified.
MYTH: Rising rates mean autism is becoming more severe.
FACT: Increased identification includes milder and previously overlooked presentations.
MYTH: Autism is overdiagnosed.
FACT: While some concern exists about overdiagnosis, research suggests a more accurate interpretation is that people have been historically underdiagnosed and that improved detection and broader inclusion criteria have increased the diagnostic rate of autism. The increase is more reflective of diagnostic expansion than misclassification.
Why is the “Epidemic” Narrative Harmful?
“Epidemic” implies that there is a disease or health-related event spreading unexpectedly. Framing autism as an epidemic can reinforce the belief that an increase in cases is contagious or harmful or that autistic individuals need to be fixed.
This wording can also reinforce stigma toward how we see autism and increase fear around seeking a diagnosis.
It can also shift focus away from ensuring autistic people have access to appropriate supports across the lifespan and toward cure language. Since autism is a neurodevelopmental disorder, “cure language” can be harmful because it focuses on something that isn’t needed.
A Neurodiversity-Affirming Perspective
When we consider the conversation around autism, a helpful way to look at the increase in autism diagnoses is through a neurodiversity-affirming perspective.
A neurodiversity-affirming approach looks at autism as natural differences that shape how people experience the world, rather than a problem to be eliminated or fixed.
Under this perspective, an increase in diagnosis rates is seen as a reflection of visibility, not a global health crisis or epidemic. Support and inclusion are also centred, instead of the focus being on eliminating or fixing autistic people, which is the case if society wrongfully sees autism as an ‘epidemic.’
Instead of asking, “Why is autism increasing?” a more accurate question might be “How can we better support the people we are now able to see and understand?”
This shift moves us away from panic-based narratives and toward meaningful action, where we focus on accessibility, education, support, and acceptance of neurodiversity.
FAQ: Autism Diagnosis Rates
Is there an autism epidemic?
No. The term “epidemic” is not supported by epidemiological research. Autism is not spreading; however, it is being more accurately identified.
Why are autism rates increasing?
Main reasons include broader diagnostic criteria, increased awareness, improved screening, and better recognition of previously underdiagnosed groups.
Did autism exist in the past?
Yes. Autism has always existed, but was often misdiagnosed or unrecognized.
Are more children becoming autistic today?
There is no strong evidence that incidence has significantly increased. Most changes reflect identification practices.
Why are more adults being diagnosed now?
Many adults were missed in childhood due to outdated diagnostic criteria and a lack of awareness of autism in non-male presentations.
Book a Free Consultation With Blue Sky Learning
If you are a neurodivergent individual or caregiver seeking support, Blue Sky Learning offers virtual coaching and therapy options tailored to neurodiversity-affirming care.
We offer free 20-minute consultations by emailing hello@blueskylearning.ca or booking on our website below.
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