Thread by @Richard_Autism

Crikey, does anyone else get moments of inspiration when they are doing nothing serious, i.e., "trivial" activities (e.g., for me, making cups of tea, going to the shops, in the bathroom etc)?

Subtext to this, I just had a potentially important one. Yesterday's one about @PDASociety acting like a disreputable information source on PDA by claiming research has not disclosed conflicts of interest as "more authoritative".

For the record, I do not view the PDA Society, or the clinic which did that research as particularly reputable information sources on PDA. Presently viewing them akin to reputability of "pro" ABA/ PBS supporters on ABA/ PBS.

To be clear, it is not just those two parties I have issues with as PDA information sources. I obviously have issues with likes of Christie, O'Nions & to a lesser extent Happe.

There is a substantial amount of things which seems to get overlooked by "PDA as an ASD" supporters to make their claim PDA is an ASD. Give one quick example on this.

So how PDA does not conform to accepted autism understandings, seems to be explained away due to possible "collider bias", a point been made by O'Nions & others in recent literature.

They seem not to consider if the best (& simplest) explanation is that perhaps PDA is not a form of autism, or even if logically Newson's PDA can be fudged in with autism.

I go into great detail on this here:


I am going to provide an abridged version.

First thing to note is that while accepted autism subtypes were replaced with single ASD in DSM-5, it is still essentially the same construct from DSM-4/ ICD10 to allow for diagnoses to be transferable between DSM4 to DSM-5.

ICD10 & DSM4 had similar definitions for Asperger's etc, based on triad of impairment. The triad of impairment has been collapsed to dyad of impairment in DSM-5.

Now for one Newson knew what triad of impairment of autism was in early 1980s & used it to diagnose equivalent of Asperger's in about 80 autistic adults. Newson was NOT trying to make PDA conform to triad of impairment.

In none of her three published diagrams for PDA does Newson seem to base PDA on triad of impairment. Two diagrams have triad of impairment in for Asperger's & Autistic Disorder.

DSM-5 ASD diagnosis represents collapsing of accepted three autism subtypes: Aspergers, Autistic Disorder & Pervasive Developmental Disorder- Not Otherwise Specified (PDD-NOS).

Now we come to a key difference between accepted DSM-4 understandings of autism spectrum, PDD-NOS, and Pervasive Developmental Disorders diagnostic groupings.

First thing to point out, in the DSM-4 PDD-NOS is a residual diagnosis for those not meeting threshold for either Autistic Disorder or Asperger's Syndrome, hence why these three diagnoses represent accepted autism spectrum.

Newson viewed the autism spectrum to ONLY be made up of Asperger's & Autistic Disorder, it did NOT include PDD-NOS. There is a good reason for this.

This is because Newson views PDD-NOS to much broader than DSM-4 version. Newson's version includes non-autistic persons as her diagnostic grouping for Pervasive Developmental Disorders is different to DSM-4.

Accepted DSM-4 Pervasive Developmental Disorders, has:
Asperger's Syndrome
Autistic Disorder.
PDD-NOS.
Childhood Disintegrative Disorder
Rett’s Syndrome

Newson's version of Pervasive Developmental Disorders is broader than this as it includes.
Autistic Disorder
Asperger's Syndrome
PDA.
Specific Language Impairments (which include things like dyslexia & aphasia).

Prevalence rates for Specific Language Impairments is 3%-7%. Newson's PDD-NOS definition is when a person does not threshold for any of:
Aspergers
Autistic Disorder
PDA
Specific Language Impairment.

Thus Newson's PDD-NOS includes non-autistic persons, while accepted DSM4 version of PDD-NOS does NOT include non-autistic persons.

Obviously, Newson's Pervasive Developmental Disorder diagnostic grouping includes MANY non-autistic persons in, perhaps a few times more than total number of autistic persons.

Obviously, Newson's PDA cohort also includes some non-autistic persons in it. Newson screened & excluded cases who displayed features of autism, from her cohort.

"It is useful to describe Asperger syndrome and classic autism together as forming the autistic spectrum;...

... but in our view it is not useful to use ‘autistic spectrum disorders’ as synonymous with ‘pervasive developmental disorders’, as has become more prevalent lately in the UK....

... PDA is a pervasive developmental disorder but not an autistic spectrum disorder: to describe it as such would be like describing every person in a family by the name of one of its members." Newson et al 2003 supplementary notes.

Screenshot from Newson et al (2003) supplementary notes with the quoted text in.

The point here is that Newson is telling readers not to conflate her Pervasive Developmental Disorders with the autism spectrum, & it would be a mistake to do so (which ironically is something Christie likes to do).

Also due to the inclusion of Specific Language Impairments, Newson's Pervasive Developmental Disorders does not require Disorders within it to have repetitive behaviours and interests (RRBIs), obviously broader than accepted DSM-4 grouping.

Final point to make on this, the collapsing of accepted DSM-4 autism subtypes into DSM-5 autism spectrum disorder was done WITHOUT consideration of PDA.

Summing up
Newson's autism spectrum is narrower than DSM-4.
Newson's PDD-NOS is many times broader than DSM-4 & includes non-autistic persons.
Newson's Pervasive Developmental Disorders grouping is many times broader than DSM-4 & includes non-autistic persons

The point I making here, just by comparing nature of Newson's clinical constructs versus accepted iterations of the constructs, it clearly does NOT make any sense to view PDA as a form of autism.

@threadreaderapp please could you unroll?

Thank you in advance.

I would point out, that Christie & others would probably argue PDA has social communication issues & RRBIs, hence autism is best place for it go.

There are problems with this, as it is unclear if PDA has social communication issues. Even if it has social communication issues, they maybe be the RESULT of anxiety based RRBIs, & how the impact social interactions.

Simple rebuttal is that one can create a new diagnostic grouping for PDA to go into instead of autism, & Newson established the precedent for this with her own diagnostic grouping she used from 1986 - 1996.

There are other issues with viewing PDA as a form of autism, which I discuss here, including seemingly leading to weird research results like comfortable in roleplay & pretend not clustering with other demand-avoidant traits.
osf.io/3w86h/

Also worth pointing out off the top of my head, I am yet to see either Christie/ Eaton/ O'Nions/ Happe acknowledge Newson using her own diagnostic grouping before she adapted it into her own version of Pervasive Developmental Disorders.

@threadreaderapp please can you unroll again?

Thank you again.