Types of Autism Spectrum Disorders

When families first hear about Autism Spectrum Disorder (ASD), one of the most common questions is: What are the different types of autism? The answer is more complex than it may seem. Over the years, professionals have used different systems to classify autism, from older labels like Asperger’s syndrome and PDD-NOS to today’s DSM-5 classifications that group autism into one spectrum with varying levels of support needs. Recently, new research has even suggested the existence of genetic subtypes, adding another layer to our understanding.

Knowing how these classifications have evolved matters because they shape the way children are diagnosed, how support plans are created, and what services families can access. Many parents feel confused by outdated labels or worry about what a diagnosis really means for their child’s future. By exploring both the history and the most current insights, families can gain clarity and feel better prepared to advocate for their child.

In this guide, we’ll break down the types of autism spectrum disorders—from the DSM-IV’s older categories to the DSM-5’s severity levels and the latest discoveries in genetics. Whether you are a parent seeking answers, a caregiver looking for guidance, or simply someone wanting to understand autism more deeply, this article will give you a clear, evidence-based overview.

What Is Autism Spectrum Disorder (ASD)?

Autism Spectrum Disorder (ASD) is a neurodevelopmental condition that influences how a person communicates, learns, and interacts with others. Families often hear the term “spectrum” and wonder what it means. The word highlights that autism is not a single, uniform diagnosis but rather a broad range of presentations, abilities, and support needs. One child may have strong language skills but struggle socially, while another may have significant challenges in both communication and daily living. All of these profiles fall under the autism spectrum.

From a clinical perspective, ASD is defined by differences in social interaction, restricted or repetitive behaviors, and sensory processing. However, these features can appear in countless combinations, which is why understanding classifications is so important. Over the years, medical professionals have developed different systems to describe autism, from older categories like Asperger’s syndrome to today’s framework in the DSM-5. Knowing how these classifications evolved helps parents and caregivers better understand their child’s unique strengths and challenges.

At RenaSer, we believe that learning about the different ways autism has been described empowers families. Rather than focusing on rigid labels, we encourage looking at how each classification relates to support and intervention. By understanding both the historical and current perspectives, parents can approach the diagnosis process with clarity and confidence.

Historical Classifications: DSM-IV

Before 2013, autism was not referred to as one unified spectrum. Instead, the DSM-IV, a manual used by clinicians, outlined several distinct types under the category of Pervasive Developmental Disorders (PDDs). These included: Autistic Disorder (sometimes called Kanner’s Autism), Asperger’s Disorder, Rett Syndrome, Childhood Disintegrative Disorder, and Pervasive Developmental Disorder – Not Otherwise Specified (PDD-NOS).

For many families, these labels provided a starting point to understand their child’s needs. However, clinicians often disagreed about which type applied, and children with the same diagnosis could look very different in terms of strengths and challenges. This confusion led experts to reconsider whether separating autism into multiple types was the best approach for diagnosis and treatment. But, let’s explain each of them:

Autistic Disorder (Kanner’s Autism)

Autistic Disorder, often referred to as Kanner’s Autism, was one of the earliest recognized forms of autism. It was named after Dr. Leo Kanner, who first described the condition in the 1940s. Children diagnosed with this type typically showed significant challenges in communication, social interaction, and repetitive behaviors. Many also experienced delays in language development, making it difficult to express their needs or engage in conversations. This profile represented what many people once thought of as “classic autism.”

For families, a diagnosis of Autistic Disorder often brought a mix of clarity and worry. On one hand, it explained why a child might not be responding to their name, making eye contact, or showing interest in play with peers. On the other, it raised questions about what the future would look like in terms of schooling, independence, and relationships. At the time, many parents were advised to expect long-term challenges without much focus on individual strengths.

Today, the term “Kanner’s Autism” is no longer used in official diagnoses, but its history remains important. It laid the foundation for autism research and helped professionals identify patterns that would later expand into a broader understanding of the spectrum. In modern terms, children who would once have been diagnosed with Autistic Disorder are now recognized under the unified diagnosis of Autism Spectrum Disorder (ASD).

Asperger’s Disorder

Asperger’s Disorder was once considered a separate type of autism and was characterized by strong language skills paired with difficulties in social communication. Unlike Kanner’s Autism, children with Asperger’s typically developed speech within the expected age range. However, they often struggled with understanding social cues, building friendships, or managing back-and-forth conversations. Many also showed deep, focused interests in specific topics and preferred routines.

Families often found the Asperger’s label both helpful and confusing. On one hand, it explained why a child who seemed very verbal and intelligent might still face challenges in social or school settings. On the other, it sometimes led to misconceptions that children with Asperger’s were “less affected” or did not need support. In reality, many individuals with this diagnosis experienced significant anxiety, sensory sensitivities, or executive functioning difficulties that impacted daily life.

Since the release of the DSM-5, Asperger’s Disorder is no longer a separate diagnosis. Instead, these individuals are now considered part of the autism spectrum and may fall anywhere from Level 1 to Level 2 depending on support needs. While the label has faded in medical use, many people still self-identify as having Asperger’s because it reflects their personal journey and how they relate to the autism community.

Rett Syndrome

Rett Syndrome is a rare neurological disorder that was once grouped under the autism spectrum but is now recognized as a distinct condition. It is caused by mutations in the MECP2 gene and primarily affects girls. Children with Rett Syndrome often develop typically for the first 6 to 18 months of life, after which they begin to lose previously acquired skills such as speech, motor abilities, and hand use. This regression can be very distressing for families who initially believed their child was developing normally.

Symptoms of Rett Syndrome include repetitive hand movements, difficulties with balance and coordination, and slowed brain and head growth. Unlike other forms of autism, Rett Syndrome is associated with clear genetic markers, which explains why it was eventually reclassified. However, because early signs can look similar to autism—such as loss of speech or social withdrawal—it was once included under the broader autism umbrella.

For families today, the important distinction is that Rett Syndrome is no longer considered a type of autism. Instead, it is treated as its own condition, with specialized care plans and therapies. That said, there is still overlap in the kinds of supports children may need, including speech therapy, occupational therapy, and behavioral interventions to improve quality of life.

Childhood Disintegrative Disorder (CDD)

Childhood Disintegrative Disorder (CDD) was one of the rarest and most severe conditions once classified under the DSM-IV. Children with CDD typically developed normally for at least the first two years of life, gaining language, motor skills, and social abilities. Then, between ages two and four, they experienced a dramatic regression, losing skills they had previously mastered. This sudden loss of abilities often left families shocked and searching for answers.

The regression seen in CDD could affect multiple areas, including speech, toileting, play, and motor coordination. Unlike children with Rett Syndrome, there was no clear genetic explanation, which made the condition especially puzzling for researchers. The rapid decline often resulted in children requiring intensive, lifelong support, and many displayed behaviors that overlapped with other forms of autism.

Today, CDD is no longer considered a separate diagnosis. Instead, children who meet these criteria are now diagnosed with Autism Spectrum Disorder. The change reflects a broader understanding that autism can involve both developmental delays and regression, and that separating out CDD did not improve treatment or outcomes. For parents, it underscores the importance of monitoring developmental milestones and seeking support as early as possible if regression occurs.

Pervasive Developmental Disorder – Not Otherwise Specified (PDD-NOS)

Pervasive Developmental Disorder – Not Otherwise Specified (PDD-NOS) was a category used when a child showed clear signs of autism but did not fully meet the criteria for another diagnosis. It was sometimes called a “catch-all” diagnosis because it covered such a wide range of presentations. For example, a child who had mild language delays and social difficulties but did not fit the full criteria for Asperger’s or Autistic Disorder might receive a PDD-NOS label.

For families, PDD-NOS was often a confusing diagnosis. While it confirmed that a child was experiencing developmental differences, it lacked clarity about what those differences meant or how severe they might become. This uncertainty sometimes made it harder to access services, since schools or insurance providers questioned whether the child’s needs were “serious enough.” Parents often felt stuck in a gray area, unsure of what the label really meant for their child’s future.

With the DSM-5, PDD-NOS was eliminated in favor of a single Autism Spectrum Disorder diagnosis. This change has helped ensure that children who would have previously received PDD-NOS are now recognized as being on the autism spectrum and can access more consistent support. For families, it provides greater clarity and removes the ambiguity that once surrounded this broad category.

Transition to DSM-5

In 2013, the DSM-5 was published and redefined autism as one condition: Autism Spectrum Disorder. This decision was made because research showed that the older categories were inconsistent and overlapping. Instead of focusing on which “type” a child had, clinicians shifted to recognizing autism as a spectrum that could range from mild to severe.

The DSM-5 combined Autistic Disorder, Asperger’s Disorder, and PDD-NOS into a single diagnosis. Rett Syndrome and Childhood Disintegrative Disorder were no longer included under ASD. This change helped create a clearer, more consistent framework for families and professionals.

For parents, the transition may have been confusing at first, especially if a child had previously been diagnosed with Asperger’s or PDD-NOS. Today, those terms are still sometimes used informally, but the official medical diagnosis is always Autism Spectrum Disorder. This unified approach ensures that children can access services based on their needs rather than being limited by a subtype label.

Understanding DSM-5 Severity Levels

Instead of dividing autism into separate types, the DSM-5 introduced three levels of severity to reflect how much support a person requires in daily life. These levels are not meant to define someone’s potential but to guide access to services and supports.

• Level 1 – Requiring Support: Individuals may have noticeable difficulties with social interaction or flexible thinking, but often manage daily life with minimal assistance.

• Level 2 – Requiring Substantial Support: Challenges are more obvious, and significant support is needed in communication, social skills, and adapting to changes.

• Level 3 – Requiring Very Substantial Support: Individuals face serious difficulties in communication and behavior, and need consistent, intensive support across environments.

It is important to remember that these levels are not permanent labels. A child may need more support at certain stages of development and less at others. For example, with early intervention and ongoing therapy, many children can move from requiring “substantial support” to “support.” At RenaSer, we emphasize this dynamic view and focus on growth, not limitations.

Outdated Labels: High-Functioning & Low-Functioning

Outside of clinical settings, families often hear terms like “high-functioning autism” or “low-functioning autism.” While these phrases were once common, they are now discouraged by professionals. The reason is that such labels oversimplify a person’s abilities and can be misleading.

For instance, a child described as “high-functioning” may have strong language skills but experience severe anxiety or social difficulties. On the other hand, a child labeled “low-functioning” may struggle with verbal communication but demonstrate remarkable problem-solving or memory skills. These labels risk minimizing the real challenges individuals face while overlooking their strengths.

Instead, clinicians and therapists prefer to focus on individual support needs. Every person with autism has a unique profile, and progress should be measured by how well interventions meet those needs. At RenaSer, we encourage families to move away from stigmatizing terms and embrace a more personalized view of their child’s development.

Emerging Genetic Subtypes: 4 New Insights

In 2025, researchers made a groundbreaking discovery: autism may actually consist of four distinct genetic subtypes. These findings, based on large-scale studies of genetic and behavioral data, suggest that different biological pathways contribute to autism traits.

Each genetic subtype appears to have unique characteristics, including differences in social interaction, sensory processing, and medical comorbidities. While this research is still in its early stages, it could lead to more personalized approaches to therapy and healthcare. For example, future treatments may be tailored to a child’s specific genetic profile rather than using a one-size-fits-all approach.

For families, this research reinforces an important point: autism is highly diverse, and no two children are alike. The discovery of genetic subtypes does not replace the current DSM-5 classification, but it offers hope for more precise interventions in the years ahead. At RenaSer, we stay up to date with these scientific advances to ensure our families benefit from the latest understanding of autism.

Why These Classifications Matter for Diagnosis & Support

You may wonder why these changes in classification are so important. The truth is that how autism is defined directly affects access to services, educational supports, and insurance coverage. When autism was divided into multiple types, families sometimes struggled to qualify for resources. The shift to a unified diagnosis under DSM-5 has made it easier to ensure that all individuals receive the help they need.

Severity levels also play a role in tailoring support. For instance, knowing that a child requires “substantial support” guides educators and therapists in building individualized plans. At the same time, avoiding outdated labels helps preserve dignity and highlights potential rather than focusing on limitations.

Finally, new research on genetic subtypes opens the door for even more personalized care in the future. Families who understand these developments can better advocate for their children, ask informed questions, and seek out therapies that align with their child’s unique needs. At RenaSer, we see education as the first step to empowerment.

Conclusion

The way autism has been classified has changed significantly over the years, from the DSM-IV’s separate categories to the DSM-5’s unified diagnosis, and now toward exciting discoveries about genetic subtypes. These shifts reveal just how complex and varied autism is, reminding us that no two individuals on the spectrum are exactly alike.

For parents and caregivers, these terms and levels are not meant to place limits but to guide support. Whether a child requires minimal assistance, more intensive daily help, or falls into a future genetic classification, what matters most is seeing their individuality and ensuring they have the right tools and interventions to thrive.

At RenaSer, we are committed to walking with families on every step of this journey. Through compassionate, evidence-based ABA therapy, we adapt care to each child’s unique strengths and challenges. If you are seeking clarity, support, or personalized guidance, our team is here to provide the expertise and care your family needs.