Following ADHD long-term: "a persistence rate of 27.8%"

Studies such as the one published by Michel Lecendreux and colleagues [1] always catch my attention. Research that follows a group of people over a period of years makes for interesting reading; not least because one gets a flavour for what *could* happen when such findings are applied to a larger population.

The Lecendreux findings focused on a few important issues pertinent to a diagnosis of attention-deficit hyperactivity disorder (ADHD) specifically related to (a) the persistence of ADHD, and (b) the idea that signs and symptoms of ADHD not meeting the thresholds for a diagnosis of ADHD might be rather important. Indeed, that they may merit "a subthreshold diagnostic category" of their own.

So, based on a starting participant sample of just over a thousand families including a child in the "6-12 years age range", interviews were conducted covering various aspects of ADHD and beyond: "symptoms of ADHD, conduct disorder, and oppositional defiant disorder as well as family living situation, school performance, sleep disturbance, eating habits, use of supplemental iron, and history of ADHD treatment." Approaching half of the original sample (492 / 1012) were followed up some 9 years later where "the persistence of ADHD and its impairments and the emergence of new conditions were assessed."

Results: "At follow-up, 16.7% of the children diagnosed with ADHD at baseline met full criteria for ADHD and 11.1% met criteria for subthreshold ADHD, yielding a persistence rate of 27.8%." Diagnosis of ADHD was, by the way, based on DSM-5 criteria (see here). That figure of 27.8% in terms of ADHD persistence from childhood to early adulthood is potentially an important one. It tells us that for a majority of children diagnosed with ADHD in childhood, their symptoms of inattention, hyperactivity and impulsivity will reduce to such a degree that they are no longer considered clinically significant or at least not reaching thresholds for a diagnosis of ADHD. Whether such a reduction in symptoms is through processes such as maturation or the timely implementation of intervention/management strategies needs quite a bit more work. Whether also ADHD potentially 'morphs' into something else as people age also needs further exploration (see here).

Another important detail was also mentioned by Lecendreux et al: "Among children not diagnosed with ADHD at baseline, 1.1% met criteria for ADHD at follow-up." Such a figure is important in relation to the concept of adult-onset ADHD [2] and the question of whether ADHD is a diagnosis with foundations always rooted in infancy. The Lecendreux findings suggest that for some people, this might not be the case and opens the door to possible talk about acquired ADHD for examples. This also sounds very familiar (see here).

Insofar as the issue of a possible 'subthreshold diagnostic category' for ADHD, I find myself agreeing with the "dimensional conceptualization" mentioned by the authors. Several other conditions / states / diagnoses have recognised 'lite versions' of the label. In autism for example, one might see this as social communication disorder (SCD) or mention of the broader autism phenotype (BAP). I'm even minded to place the label known as pathological demand avoidance (PDA) in a similar bracket given recent opinions (see here). Such chatter about 'lite' does not and should not downplay the effects of such sub-threshold labels. It merely acknowledges that there may be a wider spectrum of issues / difficulties experienced outside of the receipt of a core diagnosis.

So it should perhaps be the same with ADHD too, given what is beginning to emerge on the long-term 'effects' that a diagnosis of ADHD and subthreshold ADHD might bring (see here and see here).

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[1] Lecendreux M. et al. A 9-Year Follow-Up of Attention-Deficit/Hyperactivity Disorder in a Population Sample. J Clin Psychiatry. 2019 May 7;80(3). pii: 18m12642.

[2] Cooper M. et al. Investigating late-onset ADHD: a population cohort investigation. J Child Psychol Psychiatry. 2018 Oct;59(10):1105-1113.

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More welcomed (and interesting) research on pathological demand avoidance (PDA)

Pathological demand avoidance (PDA) [syndrome] is a label that currently occupies an unusual place in psychiatric and developmental circles. Defined by "obsessive non-compliance, distress, and florid challenging and socially inappropriate behaviour", PDA has seemingly found a place (somewhere) on the autism spectrum, but at the time of writing, does not actually occupy any unique position in any of the current systems of diagnostic classification mentioning autism (e.g. DSM, ICD). The National Autistic Society (NAS) here in Blighty talk about PDA in the context of "a behaviour profile within the autistic spectrum" but that's just one description among others.

The rise and rise of the term PDA as a specific diagnosis is firmly rooted (geographically) here in Blighty. This is probably as a result of the first description of PDA emanating from the late Elizabeth Newson during her time at the Early Years Diagnostic Centre (now called the Elizabeth Newson centre). Not everyone however is totally convinced that PDA is an independent syndrome (see here) or indeed, whether it is deserving of its specific and exclusive link with the autism spectrum at the cost of other labels... I'll be touching on that last point again in this post.

After that long introduction, I bring the findings reported by Vincent Egan and colleagues [1] to the blogging table, and some more welcome research in this area. The name of the research game for Egan et al was to adapt the Extreme Demand Avoidance Questionnaire (EDA-Q) "an informant-rating instrument" into a self-report version - the Extreme Demand Avoidance Questionnaire—Adult version (EDA-QA). Two studies are reported on in this context: "In Study 1, we use this measure to examine the relationship between PDA traits, ASD [autism spectrum disorder] traits, and other psychopathology dimensions, in a community sample of adults reporting self-identified psychopathology" and: "The second study examined the EDA-QA in a community sample and measured ASD traits more thoroughly, using the full ASQ." Yes, that's ASQ as in AQ (the Autism Spectrum Quotient) "used to quantify cognitive and behavioural features associated with ASD" and all the baggage that goes with it (see here and see here).

Results: yes, the EDA-QA was "reliable, univariate, and correlated with negative affect, antagonism, disinhibition, psychoticism, and ASQ score." This bearing in mind that the nearly 350 people who took part in study 1 were all self-reporting on the various instruments used, were "recruited from a variety of specialist on-line blogs and community forums focusing on the needs and concerns of persons with ASD" and were described as "a highly educated group." I also note that the words 'self-identifying' were also used extensively during the study write-up, specifically: "29 individuals reporting self-identified ASD also reported having PDA, 44 persons claimed to have PDA alone, and a further 19 self-identified PDA alongside depression or anxiety; separately, 59 persons claimed to have formally diagnosed ASD." Even the authors acknowledge that "self-reported ASD is not without it’s difficulties." No arguments from me there (see here and see here) and others have similar opined.

When it came to study 2 results, we are told that: "A path analysis to fit the data indicated that ASQ and EDA-QA scores were positively related." Irrespective of my various musings on how the ASQ (AQ) is not seemingly 'specific' when it comes to traits being 'linked to autism', this is an encouraging result. But there was more too... "The EDA-QA measure was associated with lower agreeableness, lower emotional stability, and higher scores on the ASQ. The effects were stronger for personality traits than for ASQ scores, suggesting it may be personality that differentiates how ASD traits are expressed, with more emotionally unstable and antagonistic persons with ASD expressing PDA-type qualities." One of the thoughts I had about this finding - 'personality that differentiates how ASD traits are expressed' - is the 'tie up' between the expression of autistic traits in relation to something like borderline personality disorder (BPD) (see here and see here) that has become more frequent in the peer-reviewed science arena recently. Yet more evidence perhaps that 'self-identifying' or 'self-diagnosis' when it comes to autism is not necessarily the most accurate measure?

The authors conclude that their instrument has promise and "could be easily integrated into assessment packages currently used with prisoners, mentally disordered offenders, and homeless people, where PDA may be suspected." Minus any big headlines regarding those particular groups (see here for example), I think examination of PDA in some of those contexts could be rather revealing. The link, for example, between PDA and offending behaviour (see here) in the context that SRED (Self-Report Early Delinquency Scale) scores - indicating "higher overall self-reported delinquency" -  significantly positively correlated with EDA-QA is an intriguing finding. That also AQ scores showed no such association with SRED scores might also suggest that PDA is not as necessarily well suited to an all-encompassing link to autism (autistic traits) as many people might think...

Let's hope that there is more research to come on the topic of PDA.

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[1] Egan V. et al. The Measurement of Adult Pathological Demand Avoidance Traits. J Autism Dev Disord. 2018 Aug 23.

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"evidence does not support the validity of pathological demand avoidance as an independent syndrome"

Pathological Demand Avoidance (PDA) mentioned in the title of this post represents "a behaviour profile within the autism spectrum" according to one authoritative source.

As I mentioned in a blogpost a few years back discussing PDA (see here), the label encompasses quite a few characteristics that overlap with facets of autism. Importantly however, it also includes a few other elements, including 'resisting and avoiding the ordinary demands of life' and the 'active use of various strategies to resist demands via social manipulation', not readily associated with autism (see here for further information). The late Prof. Liz Newson talked quite a bit about PDA [1] and I was honoured to see her speak so passionately about this topic on a few occasions.

As per the UK National Autistic Society (NAS) entry on PDA, the label is "increasingly, but not universally, accepted as a behaviour profile that is seen in some individuals on the autism spectrum." Such a description sets the scene for how things stand at the moment with regards to PDA and it's current lack of formal acceptance in the various diagnostic manuals despite relatively common usage, at least here in Blighty. The viewpoint article published by Jonathan Green and colleagues [2] is likely to provoke reactions on both sides of the debate of whether PDA is an "independent syndrome" or merely reflects "an important known range of co-occurring difficulties for many children with autism spectrum disorder." Green et al suggest the latter.

This is a difficult topic to talk about. Not least because there are quite a few children and adults who have been diagnosed with PDA. The idea that these people may have been 'mis-diagnosed' or perhaps even given the label on the basis of a diagnostic 'fad' has the potential to cause quite a bit of distress both to them, their parents / caregivers and various other people who have an interest in their education and development. I make no value judgements on the Green paper aside from looking at the quality of the [current] peer-reviewed science upon which it is based.

On the topic of the peer-reviewed science on PDA, well, the term 'limited in quantity' probably best describes it so far, which is a bit surprising given the increasingly popularity of the label. I daresay that this point probably impacted on the conclusion reached by Green and colleagues, but there are some important things to highlight so far.

The paper by Elizabeth O'Nions and colleagues [3] talking about the possibility of identifying PDA via the use of the DISCO (Diagnostic Interview for Social and Communication Disorder) covered some important issues. First: "the sense that identifying PDA features in individuals within the autism spectrum may serve an important clinical function in providing tailored educational and support strategies" is mentioned. In these times when autism is increasingly being talked about in the plural sense ('the autisms') and rarely as a 'stand-alone' diagnosis (see here), PDA perhaps represents a first important step in categorising or sub-categorising part of the autism spectrum. It's perhaps no coincidence that the name Gillberg also appears on quite a bit of the literature talking about PDA, with his interest in the overlapping concept of ESSENCE including autism (see here). I might add that this is not the first time that efforts have been made with regard to formulating a diagnostic instrument for PDA [4].

Second, O'Nions and colleagues both in their adapting DISCO to diagnosis paper and other peer-reviewed publications [5] make reference to how data suggest that "a number of the traits characteristic of PDA are not very specific to the PDA phenotype and may be relatively common across the autism and problem behaviour phenotypes." They observed for example that: "Outrageous acts and lack of concern for their effects draw parallels with conduct problems and callous-unemotional traits" and even that: "The pathological demand avoidance group displayed comparable levels of autistic traits and peer problems to the autism spectrum disorders group and anti-social traits approaching those seen in the conduct problems and callous-unemotional traits group." This is important in any debate about whether PDA is deserving of a stand-alone diagnosis status or something more 'comorbid'. It should also be viewed alongside the idea that autistic traits are not seemingly just autism-specific (see here) but also occur across various different labels and diagnoses (see here). Going back to the idea for example, that callous-unemotional and anti-social traits seem to be part and parcel of some PDA, I'll draw your attention to a group of conditions where such issues are also seemingly 'over-represented' (see here) and how such conditions are themselves over-represented when it comes to the autism spectrum [6] (see here also). In short, it's [clinically] complicated.

Finally, although by no means a specific gender-linked diagnosis, I note that there are facets of the description of PDA that could 'overlap' with issues that are 'rising' when it comes to autism and in particular, female autism. So, again from the NAS description, the phrase "appears social at first and to be people-orientated" is mentioned in connection to PDA; complemented by observations on the use of 'role-play' with regard to obtaining needs and wants. I've specifically mentioned female autism in this context because of the growing interest in how the female presentation of autism might be subtly different (camouflaged) from the male presentation (see here), bearing in mind the need not to make too many sweeping generalisations (see here).

To reiterate, I remain neutral as to the current position of PDA as a distinct entity or something more 'co-occurring' symptom-wise. I do think the Green findings should be a 'call to action' for more research on this topic in terms of symptom comparisons and importantly, symptom presentation more longitudinally. With my interest in all-things 'comorbidity' in relation to autism (see here) I'd also like to see more investigations done on how the comorbidity profile may be similar/different in relation to more classical presentations of autism. And then there's biology to consider, and whether PDA notably 'differs' across any physiological measure(s) compared with other manifestations of the autism spectrum?

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[1] Newson E. et al. Pathological demand avoidance syndrome: a necessary distinction within the pervasive developmental disorders. Arch Dis Child. 2003 Jul;88(7):595-600.

[2] Green J. et al. Pathological Demand Avoidance: symptoms but not a syndrome. The Lancet Child & Adolescent Health. 2018. March 23.

[3] O'Nions E. et al. Identifying features of 'pathological demand avoidance' using the Diagnostic Interview for Social and Communication Disorders (DISCO). Eur Child Adolesc Psychiatry. 2016 Apr;25(4):407-19.

[4] O'Nions E. et al. Development of the 'Extreme Demand Avoidance Questionnaire' (EDA-Q): preliminary observations on a trait measure for Pathological Demand Avoidance. J Child Psychol Psychiatry. 2014 Jul;55(7):758-68.

[5] O'Nions E. et al. Pathological demand avoidance: exploring the behavioural profile. Autism. 2014 Jul;18(5):538-44.

[6] Gordon-Lipkin E. et al. Anxiety and Mood Disorder in Children With Autism Spectrum Disorder and ADHD. Pediatrics. 2018 Mar 30. pii: e20171377.

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Autism and the 'female camouflage effect'

Two papers provide some blogging fodder today. The first is from Agnieszka Rynkiewicz and colleagues [1] (open-access available here) who introduces a concept that many people with an interest in autism might have considered: a 'female camouflage effect' in autism. The second paper is by C Ellie Wilson and colleagues [2] and continues the idea that sex/gender differences present in autism might have some important implications for diagnostic evaluation.

Both these papers entertain the idea that although the history of autism has been very 'male-dominated' in light of the sex ratio for the label for example (see here), science and clinical practice is coming round to the idea that there may be important sex/gender differences in the presentation of core issues (see here) that might mean quite a few females have been 'over-looked' or 'under-identified' when it comes to autism. It's of increasing interest.

Rynkiewicz et al set about to present "an innovative computerized technique to objectively evaluate the non-verbal modality of communication (gestures) during two demonstration tasks of ADOS-2 (Autism Diagnostic Observation Schedule, Second Edition)." ADOS, by the way, is one of the gold-standard assessment instruments designed with autism in mind (see here). As part of their really interesting report on "automated coding of non-verbal mode of communication (gestures)" and computation of a "Gesture Index (GI)" they compared results from boys and girls ("high-functioning" as they describe them) and whether "females with autism had a higher GI compared to males with autism."

After data were crunched and the like, the authors concluded that: "High-functioning females with autism might present better on non-verbal (gestures) mode of communication than boys with autism." Further: "This may be because they are effective at camouflaging other diagnostic features." Potentially very important information indeed.

The second paper by Wilson et al continues the theme that sex/gender might have a part to play on the manifestation of autism and onwards diagnostic evaluation. With the aim of reporting "sex differences in clinical outcomes for 1244 adults (935 males and 309 females) referred for autism spectrum disorder assessment", researchers found among other things that: "Males had significantly more repetitive behaviours/restricted interests than females." Onwards: "The sexes may present with different manifestations of the autism spectrum disorder phenotype and differences vary by diagnostic subtype."

Variation in the presentation of repetitive and/or restricted behaviours/interests by sex has been talked about in the peer-reviewed research before [3]. As part of a wider suggestion of a specific female phenotype of autism potentially emerging (see here) (being careful with those generalisations) I'd like to think that a greater awareness of such issues could notably enhance the whole diagnostic system especially for females. Indeed, one area that I think would substantially benefit from a little more inspection of a potential 'female camouflage effect' in autism is that of the 'diagnosis' (although not formally noted in standardised texts) of pathological demand avoidance (PDA). At least one person has talked about female autism and the overlap with PDA (see here) and I'm minded to suggest that they might be on to something rather important.

Oh, and since I'm on the topic of sex/gender and autism, I'm minded to bring in the paper by Katarzyna Chawarska and colleagues [4] talking about infant 'at-risk for autism' girls and social attention potentially pertinent to discussions on any female camouflage effect...

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[1] Rynkiewicz A. et al. An investigation of the 'female camouflage effect' in autism using a computerized ADOS-2 and a test of sex/gender differences. Mol Autism. 2016 Jan 21;7:10.

[2] Wilson CE. et al. Does sex influence the diagnostic evaluation of autism spectrum disorder in adults? Autism. 2016. Jan 22.

[3] Van Wijngaarden-Cremers PJ. et al. Gender and age differences in the core triad of impairments in autism spectrum disorders: a systematic review and meta-analysis. J Autism Dev Disord. 2014 Mar;44(3):627-35.

[4] Chawarska K. et al. Enhanced Social Attention in Female Infant Siblings at Risk for Autism. Journal of the American Academy of Child & Adolescent Psychiatry. 2015. Dec 17.

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Rynkiewicz, A., Schuller, B., Marchi, E., Piana, S., Camurri, A., Lassalle, A., & Baron-Cohen, S. (2016). An investigation of the ‘female camouflage effect’ in autism using a computerized ADOS-2 and a test of sex/gender differences Molecular Autism, 7 (1) DOI: 10.1186/s13229-016-0073-0




Wilson CE, Murphy CM, McAlonan G, Robertson DM, Spain D, Hayward H, Woodhouse E, Deeley PQ, Gillan N, Ohlsen JC, Zinkstok J, Stoencheva V, Faulkner J, Yildiran H, Bell V, Hammond N, Craig MC, & Murphy DG (2016). Does sex influence the diagnostic evaluation of autism spectrum disorder in adults? Autism : the international journal of research and practice PMID: 26802113

Pathological Demand Avoidance

This is a bit of a different post in that it's more descriptive than opinion. I would however say that the subject matter is important, particularly given the upcoming changes to the DSM criteria for 'autism spectrum disorders' that have been the subject of so much discussion and speculation.

Pathological Demand Avoidance (PDA). I first heard about PDA quite a few years ago at a small conference held in North-East England. Prof. Elizabeth Newson and colleagues from Nottingham presented some data on the definition of PDA and the varied ways in which PDA was distinguished from, and related to, other autism spectrum conditions. The main features of PDA (as taken from Newson et al*) are:

• A passive early history (watching not interacting) which merges into becoming actively passive (objecting to normal demands).
• Demand avoidance characterised by resisting the ordinary demands of life via social manipulation.
• Apparent lack of sense of social identity, shame or pride (no sense of responsibility).
• Mood lability and a need for control.
• No problem with role playing or pretend play.
• Language delay as a result of passivity.
• Obsessive behaviour.
• Neurological impairment (clumsiness, physical awkwardness).

There are quite a few summaries of this information (one of which can be viewed here). The main differences I take from these description compared with autism seems to focus on the child's intentions, and in particular, the active use of 'social manipulation' in PDA to action those intentions, coupled with no evidence of role and/or pretend play problems. I don't see any plans to formally include PDA in DSM or any other diagnostic text and am a little uncertain why, given that conditions such as Oppositional Defiant Disorder (ODD) have found a place in the diagnostic texts (and will continue to do so).

That's it. And because this was such a short post I leave you with probably the best music video ever - 'Buddy Holly' by Weezer for all you fans of the Fonz.

* Newson E, Le Marechal K, David C. Pathological demand avoidance syndrome: a necessary distinction within the pervasive developmental disorders. Archives of Disease in Childhood. 2003; 88: 595-600.