From Childhood Schizophrenia to ASD

The Classification of Autism Over Time

#neurodiversity #autism

This is a list of diagnoses that have, historically or currently, been given to autistic people. It includes outdated, pathologizing and possibly offensive language.

The terms in italics are diagnoses that were already considered forms of autism at the time. All other diagnoses are related to autism in some way, for example because of similar characteristics. They are diagnoses that may have been given to autistic children before their traits were recognized as signs of autism.

Note: The term “autism” as used in the DSM-I and DSM-II refers to a “pervasive lack of responsiveness to other people”

Diagnostic and Statistical Manual of Mental Disorders (1952)

Schizophrenic reaction, childhood type Here will be classified those schizophrenic reactions occurring before puberty. The clinical picture may differ from schizophrenic reactions occurring in other age periods because of the immaturity and plasticity of the patient at the time of onset of the reaction. Psychotic reactions in children, manifesting primarily autism, will be classified here.

Diagnostics and Statistical Manual of Mental Disorders, Second Revision (DSM-II, 1968)

Schizophrenia, childhood type This category is for cases in which schizophrenic symptoms appear before puberty. The condition may be manifested by autistic, atypical, and withdrawn behavior; failure to develop identity separate from the mother's; and general unevenness, gross immaturity and inadequacy in development. These developmental defects may result in mental retardation, which should also be diagnosed.

International Classification of Diseases, 9th Revision (1978)

The 6th to 8th revisions of the ICD already included a chapter on mental disorders, but the 9th was the first to classify autism.

The following “Pervasive Developmental Disorders” (PDD) were classified in the chapter of “Other Psychoses”:

Autistic Disorder Disorder beginning in childhood marked by the presence of markedly abnormal or impaired development in social interaction and communication and a markedly restricted repertoire of activity and interest; manifestations of the disorder vary greatly depending on the developmental level and chronological age of the individual [This] type of autism [is] characterized by very early detection (< 30 months), social coldness, grossly impaired communication, and bizarre motor responses

This diagnosis comes closest to the type of autism first described by Leo Kanner in his 1943 paper “Autistic Disturbances of Affective Contact”. Alternative terms listed in the ICD-9 are “Kanner's syndrome”, “Childhood autism” and “Infantile Psychosis”

Childhood Disintegrative Disorder A pediatric disorder characterized by normal development for at least the first two years of life followed by a severe regression in language, social interaction, bowel or bladder control, and/or motor skills. The affected individual may also exhibit repetitive and stereotyped patterns of behavior similar to autism.

This type was originally described by Theodor Heller in 1908, making it possibly the earliest known form of autism. Heller considered it to be a type of childhood dementia (“dementia infantilis”). An alternative term used in the ICD-9 is Heller's Syndrome.

Other Specified Pervasive Developmental Disorders Neuropsychiatric disorder whose major manifestation is an inability to interact socially; other features include poor verbal and motor skills, singlemindedness, and social withdrawal Syndrome or disorder usually first diagnosed in childhood, characterized by severe and sustained impairment in social interactions and restricted, repetitive patterns of behaviors, interests, and activities

This diagnosis included multiple terms, including:

Unspecified Pervasive Developmental Disorder

This category was used to diagnose people who met the overall description of a “pervasive develoomental disorder” but didn't qualify for any of the above diagnoses. This diagnosis is often simply referred to as “autistic traits”.

DSM-III (1980)

The DSM-III classification of autism was overall very similar to the ICD-9, since they were published at around the same time. The descriptions in the DSM starting with the third revision are much more detailed than the ones in it's predecessors. So instead of copying the entire descriptions, I will summarize them best as I can.

Like the ICD-9, the DSM-III also used a category called Pervasive Developmental Disorders which included:

Infantile Autism

Equivalent of the ICD-9 Autistic Disorder. A key characteristic was a “pervasive lack of responsiveness to other people”, which actually used to be the definition of the word “autism”. Other signs were language deficits, absent or “peculiar” speech (e.g. echolalia), a resistance to change, and “peculiar” attachments to objects or topics. Infantile Autism was believed to be about three times more common in boys than in girls. It was also considered very rare, with 2-4 out of 10,000 cases.

Childhood Onset Pervasive Developmental Disorder

This type of autism was believed to have its onset later than Infantile Autism (between 30 months and 12 years of age). Diagnosis required a “gross and sustained impairment in social relationships”, as well as other characteristics. Those other characteristics could include things like sensory hyper- or hyposensitivity, “oddities of motor movements” (stimming), resistance to change, or certain differences in emotion or nonverbal communication. “Sudden explosive anxiety” was also considered a trait of childhood onset PDD. This diagnosis is the first (in either the ICD or DSM) to recognize differences in sensory processing as an autistic trait.

Atypical Pervasive Developmental Disorder

Equivalent of ICD-9 unspecified PDD

In another category (Other disorders of infancy, childhood and adolescence), the DSM-III included the diagnosis:

Schizoid Disorder of Childhood and Adolescence

This used to be considered an early-onset personality disorder, but today “Schizoid Disorder of Childhood” is believed to be a part of the autism spectrum. Characteristics included social isolation and -anhedonia (a lack of enjoyment of social interaction), an apparent disinterest in friends, and a lack of interest in social activities. It's important to remember that psychology is only starting to take into account the actual thoughts and opinions of autistic people; diagnoses like this one were likely often made based on perceived behavior rather than what the child actually wanted.

ICD-10 (published 1990, used 1994-Dec 2021) and DSM-IV (1994)

Putting these together because they are extremely similar. Like their respective predecessors, both of these use the category “Pervasive Developmental Disorders” to diagnose autism:

Autistic Disorder (DSM) or Childhood Autism (ICD)

Characteristics are divided into three groups: 1. “Impairment in Social Interaction” 2. “Impairment in Communication” 3. “Restricted, repetitive and stereotyped patterns of behavior, interests, and activities”

In addition, one of these three needs to be present before the age of three years: “Delay od abnormal functioning in” 1. Language 2. Reciprocal social interaction 3. Symbolic Play

Childhood Disintegrative Disorder

CDD includes a typical development for two years, then a sudden loss of skills between the ages of two and ten. Those skills may include language, social skills, bladder control, play, or motor skills.

It also includes the same three sets of characteristics as seen in “Autistic Disorder” / “Childhood Autism”

Asperger's Disorder (DSM) or Asperger Syndrome (ICD)

A form of autism with no significant delays in language or cognitive development. Diagnosis only requires “impairment in social interaction” and “repetitive behavior, not impairment in communication” (Although it should be mentioned that nonverbal communication is mostly covered by the social interaction aspect)

While the ICD-10 and DSM-5 criteria are very similar to each other, there are other descriptions and sets of diagnostic criteria that directly contradict these or one another. In other words, nobody is quite sure what exactly AS even is – it seems to have been used to describe multiple types of autism that are in some way similar to Hans Asperger's descriptions of his patients.

One of the alternative terms listed in the ICD-10 is “Schizoid Disorder of Childhood”, hence why I listed that diagnosis earlier.

Atypical Autism

In the DSM, this is includes in Pervasive Developmental Disorder – Not Otherwise Specified, but in the ICD, it's a separate diagnosis. Atypical Autism refers to a form of autism that does not meet criteria for childhood autism, either because the minimum number of traits aren't met, or because autistic traits first occured after the age of three, or both.

Other Pervasive Developmental Disorder

Pervasive Developmental Disorder – Not Otherwise Specified, including Atypical Autism (DSM) or Unspecified Pervasive Developmental Disorder (ICD)

This diagnosis is given to people who have characteristics of PDD but who don't meet the criteria for any specific one. According to some studies, PDD-NOS includes three main groups of people:

  1. Those who do not have impairments in communication (and thus don't meet criteria for Childhood Autism) but who have a language or cognitive delay (and thus don't meet criteria for Asperger Syndrome)
  2. Those whose autistic traits can't be fully identified, for example because they were diagnosed later in life (and may not have records of their childhood), or because intellectual disability/ communucation difficulties make ir difficult to udentify autistic traits
  3. Those who mostly meet the criteria for Childhood Autism/ Autistic Disorder, but with little repetitive behaviors

Pervasive Developmental Disorders that are not considered forms of autism [anymore] include:

DSM-5 (2013) and ICD-11 (published 2018, used starting 2022)

In the most recent diagnostic manuals, autism has been merged into one diagnosis:

Autism Spectrum Disorder

ASD includes two main categories: 1. “Persistent deficits in social communication and social interaction”. This includes deficits in social-emotional reciprocity, nonverbal communication, and relationships. 2. “Restricted, repetitive patterns of behavior, interests, or activities”, including characteristics such as sensory hypo- or hypersensitivity, stimming, need for sameness or routine, or intense interests.

ASD is also the first diagnosis to recognize that a. Autistic traits may be masked later in life b. Autistic traits may not become obvious until demands become too high

This last part makes the diagnosis more inclusive, and adult diagnosis easier and more common. However, a diagnosis of ASD requires a lot more characteristics than previous diagnoses, especially in the area of social interaction.

Because of this, only ca. 57% of all people diagnosed with Autistic Disorder, Asperger's Disorder, or PDD-NOS meet the criteria for ASD. This mostly affects those diagnosed with PDD-NOS, followed by those with Asperger Syndrome. Those diagnosed with Autistic Disorder meet the criteria for ASD in 3 out of 4 cases.

The DSM-5 does specify that people who received any of the above diagnoses using the DSM-IV, should receive a diagnosis of ASD. However, a lot of people who are (or will be) assessed later will not meet criteria for ASD, even though they previously would have received a diagnosis of a PDD. The most common reason for this is not meeting the threshold for “impairments in social interaction and communication”. A diagnosis for Asperger's, for example, only required one out of three characteristics in this area, while a diagnosis of ASD requires all three.

Social (Pragmatic) Communication Disorder (DSM only)

This diagnosis is closely related to autism and has been called a “reincarnation of PDD-NOS”.

More specifically, it would probably fit the third “type” of PDD-NOS quite well – SCP is characterized by similar difficulties in communication as ASD, but a lack of repetitive behavior. The DSM specifies that autistic people may mask repetitive behavior later in life so SCP should only be diagnosed if the person has never met that part of the ASD criteria.

SCP includes four main characteristics:

  1. “Deficits in communication for social purposes”, e.g. greeting
  2. Problems adapting communication to context
  3. Difficulties following rules for communication
  4. Difficulty understanding nonliteral aspects of language (e.g. sarcasm)
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