Monday 27 January 2014

Stability and trajectories in childhood autism

A quote to begin this post taken from the paper by Patricia Towle and colleagues*: "approximately 20% no longer had ASD diagnoses". The background to this observation was a study utilising a "chart abstraction protocol" to examine the longitudinal presentation of autism and in particular, "establishing a rate of diagnostic stability for school-aged children diagnosed with ASD early".
Keep calm and... @ Wikipedia

Stability, and in particular, the diagnostic stability of autism, is fast becoming an interest of mine. I've talked about it a few times with reference to the continued rush to diagnose autism earlier and earlier (see here) and that rather interesting body of work which suggests that in amongst the various trajectories of autism, one of them might include an "optimal outcome" group of children who move out of the diagnostic boundaries that are autism.

Some details. The Towle paper looked at 80 children who were identified with an autism spectrum disorder (ASD) early; as in before the age of 3 years (16-36 months; Time 1). Parents of some of the children provided various details about their child at a follow-up period (7-16 years; Time 2) in order to ascertain where they were at school age including determining diagnosis. As you've probably realised, determining diagnosis involved a review of the various data available to authors and not a formal face-to-face assessment.

Their results from the various data sources analysed suggested a few things. As per the beginning quote, about 20% of the children went "off the spectrum". That being said the authors also report that "important learning challenges" remained for this group which ties in quite nicely with my recent review of optimal outcome (see here). Off the spectrum did not also imply free of the need for classroom support. Towle and colleagues also reported some interesting trends across their various groupings outside of just those related to the "No ASD/LD" category. That for example, attentional issues were pretty widespread across their cohort with a diagnosis of ASD (whether moderate/severe or mild) is informative. Again without boasting, I have talked about the link between autism and conditions like ADHD, and in particular the question of whether managing attentional issues might have some knock-on effects to the presentation of core behaviours. There are quite a few other important factoids to take from the Towle paper but not for today and not for this post.

Whilst however I'm on the topic of trajectories, I wonder if it might also be worthwhile introducing the paper by Venker and colleagues** and their analysis of trajectories of autism severity based in part on calibrated severity scores derived from the Autism Diagnostic Observation Schedule (ADOS). The long-and-short of it was that based on a group of children diagnosed with an ASD, severity trajectories, four of them, were plotted derived from annual follow-ups using ADOS and other measures. Those trajectories were: persistent high, persistent moderate, worsening and improving.

Venker et al found that 80% of their participant group fell into the persistent high and persistent moderate groupings meaning that for the majority of children, there was "little change in overall severity level during early development". That being said, 14% of their sample were placed in the 'improving' grouping and 6% in the 'worsening' grouping hinting at a more fluidic profile for some children on the autism spectrum.

So, there you have it. Two very different ways of looking at autism: chart abstraction vs. annual formal assessment demonstrating both diversity in developmental trajectories in autism and also at least some degree of instability in terms of presented symptoms for some. Whilst the Venker paper has the upper hand in terms of the use of a formal, objective assessments, it's actually the Towle paper which perhaps gives a bigger picture of autism in terms of their focus on other comorbidity and how it may very much complete the clinical picture of autism. Comorbidity might actually turn out to be pretty important for autism as I've hinted about in other posts.

Oh, and I'll be talking about the Deborah Anderson paper*** fairly soon too so stayed tuned.

To close, the picture included with this post, of the 'Keep calm and carry on' ilk also ties into a recent feature I read about the Minnesota experiment during WW2. If you're really interested, I was also brought to quite an interesting paper on the topic (see here, open-access) (with thanks to Mary Mangan & Jeremy Yoder on G+ for the link).


* Towle PO. et al. School-Aged Functioning of Children Diagnosed with Autism Spectrum Disorder Before Age Three: Parent-Reported Diagnostic, Adaptive, Medication, and School Placement Outcomes. J Autism Dev Disord. 2013 Dec 18.

** Venker CE. et al. Trajectories of Autism Severity in Early Childhood. J Autism Dev Disord. 2013 Aug 2.

*** Anderson D. et al. Predicting young adult outcome among more and less cognitively able individuals with autism spectrum disorders. J Child Psychol Psychiatry. 2013 Dec 9. doi: 10.1111/jcpp.12178.

---------- Towle PO, Vacanti-Shova K, Shah S, & Higgins-D'alessandro A (2013). School-Aged Functioning of Children Diagnosed with Autism Spectrum Disorder Before Age Three: Parent-Reported Diagnostic, Adaptive, Medication, and School Placement Outcomes. Journal of autism and developmental disorders PMID: 24346492 Venker CE, Ray-Subramanian CE, Bolt DM, & Weismer SE (2013). Trajectories of Autism Severity in Early Childhood. Journal of autism and developmental disorders PMID: 23907710

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