Thread by @Richard_Autism

Thread on weaknesses of Help4Psychology PDA database:
ingentaconnect.com/contentone/bil…
From public information sources, that indicate it has severe limitations.

The database is constructed by only diagnosing PDA in those the clinic believes are already autistic. Secondly they have a narrow definition of what PDA is. Thirdly, limitations with the tools used:

First off, it assumes that PDA can only be found in autistic persons. Others argue PDA is seen outside of autism. For instance:
onlinelibrary.wiley.com/doi/full/10.11…
and can be explained by other conditions than autism:
unsafespaces.com/tag/pathologic…
and
thepsychologist.bps.org.uk/volume-29/janu…

There is evidence to support these positions:
researchgate.net/publication/33…
Single cases:
link.springer.com/article/10.100…
and:
sciencedirect.com/science/articl…
And
pdaresource.com/files/An%20exa…

Only diagnosing PDA in autistics assumes 1) Newson was correct PDA was Pervasive Developmental Disorder. Phil Christie is correct that PDA is autism subtype. I cover issues with Christie's assumption here:
onlinelibrary.wiley.com/doi/abs/10.111…
and
researchgate.net/publication/33…

Highly likely Newson was incorrect to view PDA as a PDD, she states:
"“hanging together as an entity” is not enough
if that entity is not significantly different from both autism
and Asperger’s syndrome, either separately or apart" (Newson et al 2003, p599)

This statement is supported by how Newson does not base PDA on the triad of impairment underpins modern autism diagnostic criteria. Nor does she draw PDA overlapping the triad of impairment here:

Worth noting that Newson is incorrect to view Specific Language Impairment as a Pervasive Developmental Disorder. Almost certainly incorrect PDA is 100% genetic/ biological in nature. It is reasonable to assume she her views PDA is a PDD is also a mistake.

Reason why Newson is almost certainly mistaken about the causes of PDA, is covered here:
researchgate.net/publication/33…
Also mentioned in Norwegian PDA systematic review by @OrmStian

This then leads onto that PDA literature acknowledges it is problematic fitting PDA into the autism spectrum. References:
pdaresource.com/files/An%20exa…
and
link.springer.com/article/10.100…

I also add further reasons why it is problematic fitting PDA into autism spectrum here:
onlinelibrary.wiley.com/doi/abs/10.111…
PDA has higher rates of persons not meeting clinical threshold compared to autism. PDA is: 44% - 89%. Autism is: 0% - 47%.

The figures for autism are from the Autism Dividend Report, page 52, inverted the percentages to make them comparable to PDA.
nationalautismproject.org.uk/the-autism-div…
An example of how Grahame et al (2020) have misrepresented my work.

Help4Psychology's 3 additional definitions for PDA. I cover issues with these definitions here:
researchgate.net/publication/34…
If anxiety is causing this demand avoidance; the anxiety would be obsessive in nature& the demand avoidance would be compulsive in nature.

Help4Psychology uses Wechsler Intelligence Scales to measure intelligence. The best tool for measuring autistic intelligence is Raven's Progressive Matrices.
journals.plos.org/plosone/articl…

It must be said the ADOS (Autism Diagnostic Observation Schedule) is not designed to assist any clinician/ researcher in to assessing/ identifying features of PDA. I have clarified that with ADOS publisher.

Issues using tools not as designed. EDA-Q is a research tool, it is not designed to be used to make a diagnosis of PDA. Although it is used in this capacity in PDA literature:

The EDA-Q is also noted for having a number of drawbacks which I discuss here:
onlinelibrary.wiley.com/doi/abs/10.111…
For links where EDA-Q is used to diagnose PDA:
ingentaconnect.com/contentone/bil…
and
sciencedirect.com/science/articl…

There are also issues with using the 11 validated PDA questions in a developmental history. Again these questions are not designed to be used in that manner. The 11 validated PDA questions are designed to be used with full DISCO.

Again these 11 DISCO PDA items have a number issues attached them. Mainly that they were validated with arbitrary thresholds, so these questions are essentially unvalidated. researchgate.net/publication/33…

The 11 "validated" PDA DISCO questions only assess for 6 PDA diagnostic traits. As they are essentially unvalidated, one would be better using the 15 unvalidated PDA items that assess 8 PDA diagnostic traits.

There are also problems basing PDA definitions off the PDA literature when it is acting as a community of practice, this matters as PDA literature has not really discussed issues around subtyping autism:
researchgate.net/publication/33…

There is not really an excuse for this @HappeLab has been involved in PDA research, has written about the issues of subtyping autism and was involved in developing DSM5 autism criteria:
jaacap.org/article/S0890-…

It should really not have taken me to discuss the Neurodevelopmental Disorders Workgroup's logic behind removing subtypes to get into the PDA literature, it should have been done by @HappeLab

Getting onto last few pieces of critique of Help4Psychology PDA database.

This is a weak one, but it includes significantly less PDAers than Newson's research:
Less DAPers than Newson had: 111 vs 150.

The database ideally needed to use a tool designed to diagnose PDA as a standalone construct, independent of autism; i.e. Elizabeth Newson's own semi-structured interview:
pdaresource.com/files/An%20exa…

Finally, one would expect that if @GillbergCentre conducted the study, diagnosing it in non-autistic persons, they would see many more PDAers including non-autistic ones:
link.springer.com/article/10.100…

I think that is all the critique and limitations I know of going by public sources.

Until such times that Help4Psychology PDA research results are replicated or not replicated independly using Newson's diagnostic tool and diagnosing in non-autistic persons; their PDA database needs to be treated with caution.
Over to @DrJudes03

For reasons why it is difficult to subtype/ divide autism can be found here:
link.springer.com/article/10.100…

If people need a better image of Newson's "Autistic Family" diagram.

Also 15 unvalidated DISCO PDA items, also need the full DISCO as questions to assess for delayed speech development are in full DISCO.
link.springer.com/article/10.100…

Articles by Langton and Frederickson are also important as they are clear, no consensus over how to diagnose PDA means researchers cannot rely on a PDA dx as an indicator has PDA or not:
tandfonline.com/doi/abs/10.108…

Obviously means that no-one can rely on any PDA dx as an accurate identifier if a person has PDA or not. Raises questions over accuracy of Help4Psychology's definitions are reflective of all PDAers?

@threadreaderapp please unroll

Thank you to @sofadog for this.