Knowing Where Your Child Falls Within the Spectrum

A common misconception about autism is that all children diagnosed with the disorder have exactly the same symptoms. Autism is a spectrum disorder, meaning that it has a complex range of symptoms: mild to severe. The only similarities children diagnosed with autism spectrum disorder have in common are symptoms which are a direct result of the neurological disorder. These similarities are lack or absence of communication skills, stereotyped or repetitive behaviors and difficulty or lack of interpersonal or social skills.

Archive correction — October 12, 2026: the five-category, mild-to-severe ranking below is not the current diagnostic framework. DSM-5 brought autistic disorder, Asperger’s disorder, childhood disintegrative disorder and PDD-NOS into one autism spectrum disorder diagnosis. Rett syndrome is a separate neurological and developmental condition, not a severe form of autism. The original text is retained as a historical record, not as current diagnostic guidance.

Here are the five classifications that fall under the autism spectrum disorder or ASD, listed in order of mild to severe intensity:

Asperger’s Syndrome

Within the autism spectrum disorder, Asperger’s Syndrome is considered to be the mildest. It is a high-functioning form of ASD wherein the symptoms of this disorder are lack in social and communication skills yet verbal skills and intelligence are normal.

The most distinct characteristic of Asperger’s is that sufferers tend to be obsessive with an object or an activity, making them oblivious to other things or people around them. Children with Asperger’s are also observed to have difficulty in understanding body language and tend to be literal with words.

Pervasive Developmental Disorder - Not Otherwise Specified – PDD-NOS

PDD-NOS is a catch-all diagnosis meaning that a child may exhibit some symptoms of autism yet does not specifically fall within any other category within the spectrum. To be diagnosed with PDD-NOS, a child may show some characteristics of autism yet cannot be categorized in the other four classifications. Furthermore, a child may even have a severe deficit in language skills yet still not enough to be categorized.

Autistic Disorder

Also called classic autism, children diagnosed with autism disorder exhibit more severe symptoms that those with Asperger’s and PDD-NOS. These children lack intuitive social skills, which makes them react adversely to being touched and making eye contact. Children with autism disorder also present more severe case of repetitive behavior, unconventional gestures and unresponsiveness to other people. Many children with autistic disorder need to be watched closely as they are prone to hurting others and causing self-injury.

Childhood Disintegrative Disorder

This condition is one of the most severe cases within the autism spectrum disorder. A child diagnosed with this disorder exhibits a pronounced loss in motor, language and social skills and a dramatic loss in vocabulary skills. Comorbid medical conditions such as loss of bowel and bladder control, seizures and low IQ are commonly associated with childhood disintegrative disorder.

Rett’s Syndrome

Rett syndrome is a separate genetic neurological condition, almost always in girls, caused in most cases by changes in the MECP2 gene. It is not a form of autism, though young children with Rett syndrome can go through a period that looks like autism. Children with this disorder exhibit deterioration of mental, social and communication skills. Children with Rett’s syndrome are unresponsive, even to parents, and avoid social contact and can even stop talking. Physical manifestations include loss of purposeful hand use, repeated hand-wringing or hand-washing movements, and trouble walking in addition to an obvious reduction in muscle tone, causing the child to appear “floppy”. Comorbid medical conditions such as scoliosis, gastrointestinal problems such as constipation and reflux, breathing irregularities and seizures, cardiac problems, swallowing problems and erratic sleeping problems can also be present.