#10 What else is “on the spectrum”? 

autism spectrum

So often we hear Autism Spectrum Disorder (ASD) generalized as autism, but what else is on the spectrum?  ASD is considered a spectrum disorder because there is such an array of symptoms that can be demonstrated in several different ways with varying severity.   

The American Psychiatric Association’s DSM (Diagnostic and Statistical Manual) for mental health disorders was first published in 1952.  Since then, the definition of autism has changed.  At first autistic behaviors were associated with childhood schizophrenia.  It wasn’t until 1980 and the third volume of the DSM when autism became listed as its own disorder.   

When the fourth volume came out in 1994, there were 4 subcategories under autism and 16 different criteria for diagnosis.  These 4 subcategories were Asperger’s Disorder, Rett’s Disorder, and Childhood Disintegrative Disorder, and Pervasive Developmental Disorder Not Otherwise Specified (PDD-NOS).  Asperger’s became known as high-functioning autism.  Rett’s and Childhood Disintegrative Disorders were used to describe children that began typically developing but then regressed, with autistic like symptoms.  PDD-NOS became the catchall term for those who didn’t meet all of the criteria for autism, those who presented with atypical symptoms, or those who don’t conform to a typical autism diagnosis. 


dsm5In 2013, when the fifth volume of the DSM was released, all 4 subcategories were combined into a single label, Autism Spectrum Disorder (ASD).  The removal of Asperger’s was controversial at the time.  However, the umbrella label of ASD includes autism symptoms with or without intellectual disability, with or without language impairment and with differing levels of severity. 

What is Rett’s syndrome? 

Rett’s syndrome is a genetic neurological disorder that leads to severe impairments.  It is caused by mutations on the X chromosome and occurs almost entirely in females.  The rare disorder affects 1 in 10,000 females (International Rett Syndrome Foundation).  Like autism, Rett’s syndrome has a varying degree of severity, affecting speaking, eating, walking, and breathing.  Rett’s is usually detected between 6 –18 months because of missed developmental milestones or regression.  One of the most easily identified characteristics of Rett’s syndrome is constant repetitive hand movements.  Other symptoms include: 


  • Loss of speech 
  • Loss of purposeful hands 
  • Involuntary hand movements 
  • Loss of mobility or gait disturbances 
  • Loss of muscle tone 
  • Seizures 
  • Scoliosis 
  • Breathing issues 
  • Sleep disturbances 
  • Slowed rate of growth for head, feet and hands 
  • A period of regression 

There are 4 stages of Rett’s syndrome: Stage I is the early onset stage and occurs from 6 –18 months.  The second stage is the rapid destructive stage and occurs from 1 – 4 years.  Stage III is considered the plateau stage and occurs from preschool to adulthood.  The final stage is late motor deterioration stage and is defined by loss of walking. 

Rett’s is different from autism in a couple ways.  Children have autistic like symptoms at an early age, but they disappear as they develop.  There are certain symptoms that do not occur in autism: reduced rate of head growth, loss of purposeful hands, loss of mobility and irregular breathing.  Another big difference is that people with Rett’s prefer other people to objects and they enjoy affection. 

What is Childhood Disintegrative Disorder? 


Childhood Disintegrative Disorder (CDD), or Heller’s syndrome, is a developmental disorder in which children develop normally until 3 or 4 years old and then they lose skills they have already learned (Tidy 2021).  These skills include motor skills, language development, and social skills.  The disorder is extremely rare with 1 in 100,000 boys having it.  CDD occurs 8 times more often in boys than in girls.  The cause is unknown, but the neurobiology of the brain is suspected to be a contributing factor.  Symptoms of this disorder include regression in the following areas: 

  • Expressive or receptive language skills 
  • Social skills 
  • Self-care skills 
  • Play skills 
  • Motor skills 
  • Bladder or bowel control 

Other symptoms include: 

  • Repetitive and restricted interests or behaviors 
  • Two years of normal development 
  • Gradual or rapid regression 
  • Child’s awareness of regression 
  • Emotional problems 
  • Becoming averse to physical contact 
  • Seem to be hallucinating 
  • Fearfulness 
  • Seizures 

Compared to autism, childhood disintegrative disorder creates similar social and communication difficulties.  The main difference is that there are usually 3-4 years of typical development, while those with autism begin missing milestones around 1.5 – 2 years.  Epilepsy also occurs more often in Childhood Disintegrative Disorder than with autism. 


Additional Resources: 

The CDC’s Developmental Milestone Checklist can be helpful in monitoring your child’s progress.  Autism-Help.org has lots of information on Asperger’s and the other pervasive development disorders.  Here is more information on Rett’s Syndrome. The CDC and National Institute of Health also have an abundance of information on ASD. 

Tidy, C., Knott, L. (2021). Childhood Disintegrative Disorder.  Patient Info.  Retrieved from: https://patient.info/doctor/childhood-disintegrative-disorder-hellers-syndrome  

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