3 Different Types of Autism
Autism Spectrum Disorder (ASD) is a complex neurodevelopmental condition affecting about 1 percent of the population in Singapore. Additionally, a recent report in 2021 shows that at least 400 new cases of ASD are diagnosed each year and the risk of a sibling having ASD increased by 20 percent.
Autism affects individuals in unique and diverse ways. While each person with autism is distinct, researchers have identified various types of autism that provide a framework for understanding and appreciating the spectrum.
In this blog, we will delve into the types of autism — from nonverbal autism, which uses unconventional methods of communication, through high-functioning autism, characterised by extraordinary skills and unique viewpoints — shedding light on their characteristics, challenges, and strengths. By gaining a deeper understanding of each type, we hope to promote acceptance, compassion, and inclusion for individuals on the autism spectrum.
What are the levels of autism?
ASD covers a wide range of symptoms that can vary in severity. To reflect this, the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5) defines three levels of ASD based on the amount of support the individual requires.
Level 1 "Requiring Support"
Individuals at this level can often conduct their lives independently but still face challenges with social interactions and communication. For example, they may have difficulty initiating conversations or responding appropriately to others. They may also have inflexible behaviours that create obstacles in their daily life, and they may find it challenging to switch between activities. They might not need as much support as people at Levels 2 or 3. However, they still benefit from support in certain areas, like social communication.
Level 2 "Requiring Substantial Support"
People at this level have more noticeable difficulties with verbal and nonverbal communication, which can limit their ability to function independently. They may only speak in simple sentences or repeat specific phrases. They also have noticeable difficulty with change and may engage in repetitive behaviours that are hard to redirect. Social interactions are significantly affected, and they may struggle to change focus or behaviour in different contexts. They usually need consistent support, including school or work, in their daily lives.
Level 3 "Requiring Very Substantial Support"
Individuals at this level have severe verbal and nonverbal communication deficits. They may not speak at all or may have very limited language skills. Their behaviours are highly inflexible and repetitive. Understanding and responding to social cues is hugely challenging for them, and they may become highly distressed by changes in their environment or routine. They require significant support in every aspect of their daily life to ensure their safety and care.
It’s important to remember that the required support level can change over time, depending on factors like the individual’s age, therapy, or personal development. These levels do not indicate a person’s intelligence or potential but provide a framework to understand the type and intensity of support needed.

What are the main types of autism?
Before 2013, several conditions including Autistic Disorder and Childhood Disintegrative Disorder were diagnosed separately. The different diagnoses are further classified as severe, mild, high-functioning, or low functioning. However, such terms are no longer used as they tend to overgeneralise a child’s situation. These former different conditions are now known collectively as autism spectrum disorder The main types of autism, as recognised in the diagnostic criteria of Autism Spectrum Disorder (ASD), are as follows:
Autistic Disorder
This is what most people commonly refer to as autism. Individuals with Autistic Disorder typically display significant challenges in social interaction and communication, along with repetitive behaviours and restricted interests. They may have difficulties with verbal and nonverbal communication, struggle with changes in routines, and exhibit intense focus on specific topics or objects.
Social interaction
Individuals with Autistic Disorder often experience difficulties in social interactions and forming meaningful relationships. They may struggle with understanding and responding to social cues, such as maintaining eye contact, interpreting facial expressions, or understanding gestures. Engaging in reciprocal conversations and understanding the perspective of others can be challenging. Some individuals may prefer solitary activities and struggle to initiate or sustain social interactions.
Communication
Language and communication difficulties are common in individuals with Autistic Disorder. Some individuals may have delayed language development or struggle with verbal communication altogether. They may have difficulty expressing their needs, emotions, or thoughts, and their speech may have atypical patterns, such as echolalia (repeating words or phrases) or unusual intonation. Nonverbal communication, including understanding and using gestures, facial expressions, and body language, can also be challenging.
Repetitive and restrictive behaviours
Individuals with Autistic Disorder often exhibit repetitive and restrictive behaviours or interests. These can manifest as repetitive movements like hand flapping or rocking, insistence on sameness such as rigid adherence to routines and resistance to change, and intense preoccupation with specific topics, objects, or activities. Sensory sensitivities, such as being hypersensitive or hyposensitive to certain stimuli like noise and light are also common.
Childhood Disintegrative Disorder (CDD)
Childhood Disintegrative Disorder (CDD), also known as Heller’s syndrome, is a rare developmental disorder that is characterised by the loss of previously acquired skills in multiple areas of development, including social interaction, communication, repetitive behaviour, and delays.
Social Interaction
Children with CDD experience a significant regression in social skills. They may withdraw from social interactions, exhibit decreased eye contact, and show a lack of interest in engaging with others. The loss of social abilities can be profound, leading to difficulties in forming and maintaining relationships with peers and caregivers.
Communication
CDD involves the loss of language and communication skills. Children who previously had acquired language may experience a regression in their ability to speak and understand verbal communication. They may lose vocabulary, struggle with grammar and syntax, and have difficulty expressing their needs and desires. Communication may become limited to nonverbal means, such as gestures or pointing.
Repetitive behaviours
Like other pervasive developmental disorders, repetitive behaviours can be present in CDD. Children may engage in repetitive movements, such as hand flapping, body rocking, or spinning. They may develop rigid routines and rituals and display a strong preference for sameness. These repetitive behaviours serve as a way for individuals with CDD to cope with their environment or seek sensory stimulation.
Developmental delays
Before the onset of CDD, children typically exhibit delays in certain areas of development. These delays may involve language, motor skills, or social interaction. However, they are generally not as severe as the subsequent regression observed in CDD. The developmental delays may be noticed by parents or caregivers, but the significant loss of skills distinguishes CDD from other developmental disorders.
Global Developmental Delay (GDD)
Global developmental delay (GDD) and autism are not the same thing. While they share some similarities, they are distinct conditions with different diagnostic criteria. GDD is a condition where a child does not meet developmental milestones at the expected rate, while autism is a neurodevelopmental disorder that affects social communication and behaviour. To be diagnosed under GDD, the child must also be significantly limited in at least two developmental domains.
A child can have both GDD and autism, and studies have shown a high prevalence of comorbid autism in children with GDD. However, having GDD does not necessarily mean a child has autism, and vice versa.
Global Developmental Delay is a condition where individuals diagnosed with GDD experience significant delays in multiple areas of growth and development. These delays are not specific to any single developmental area, and the symptoms can vary widely among individuals.
Social Interaction
Children may struggle with eye contact, understanding social cues, or making friends. They find it hard to make connections and form relationships, which escalates over time if unchecked.
Communication
Language development might be slow, with challenges in speaking coherently, understanding directions, and expressing needs or emotions.
Motor Skills
Delays in gross (large) and fine (small) motor skills may occur, impacting daily activities like walking, drawing, or dressing.
Cognitive Functioning
Children with GDD might face difficulties in problem-solving, memory, attention, and learning at school. Specialised support may be needed.
Emotional Development
Recognizing and managing emotions can be difficult, leading to challenges in forming emotional bonds and handling feelings like frustration or anxiety.
How ABA therapy can help children with autism
ABA therapy, or Applied Behaviour Analysis therapy, is a scientifically based approach to helping children with autism learn new skills and behaviours. Here are some ways in which ABA therapy can help children with autism:
Building life and social skills
ABA therapy can help children with autism learn social skills, such as how to initiate and maintain conversations, make eye contact, and understand social cues. It can also help them develop life skills, such as self-care, hygiene, and organisation.
Adapting challenging behaviours
ABA therapy can help children with autism learn to manage challenging behaviours, such as tantrums, aggression, and self-injury. It does this by identifying the triggers for these behaviours and teaching the child alternative, more appropriate behaviours.
Measuring changes and improvements
ABA therapy uses a systematic approach to measure changes and improvements in the child’s behaviour. This helps therapists and parents track progress and adjust the therapy as needed.
Assessing and recording progress
ABA therapy assesses and records the child’s status or progress. This helps therapists and parents identify areas where the child needs more support and where they are making progress.
Teaching language skills
ABA therapy plays a significant role in helping children with autism to start talking, which is a major concern of many parents. It can aid them in developing language skills, such as vocabulary, grammar, and sentence structure. It does this by breaking down language into smaller, more manageable parts and systematically teaching them.
Teaching play and leisure skills
ABA therapy can help children with autism learn how to play and engage in leisure activities. This can help them develop social skills and build relationships with peers.
Teaching safety skills
ABA therapy can help children with autism learn safety skills, such as crossing the street safely, identifying dangerous situations, and responding appropriately to emergencies.
Remember that every child is unique and progresses at their own pace. Some children might make progress quickly, while others may need more time. It’s essential to approach this with patience and continuous positive reinforcement. ABA therapy can be a valuable tool in helping a nonverbal child with autism to start talking, but it should always be implemented under the guidance of a trained professional.
The takeaway
The types of autism — Autistic Disorder and Childhood Disintegrative Disorder (CDD) — represent distinct profiles within the autism spectrum. While the specific terminology and classifications have evolved, understanding the characteristics of these types can still provide valuable insights into the diverse experiences of individuals on the spectrum.
Understanding these types of autism helps foster acceptance, compassion, and inclusion for individuals on the spectrum. By appreciating the diversity within the autism community and providing appropriate support and accommodations, we can create an inclusive society that values the contributions and potential of every individual, regardless of their place on the spectrum.
At AutismSTEP, we tailor a customised treatment plan that meets your child’s needs and goals. By working together and supporting one another, we can help children with autism thrive and reach their full potential.
To help you make an informed decision on the type of therapy your child needs, please schedule a consultation with us today, or call +65 6456 9950.