Wednesday, 24 October 2012

More autism developmental trajectory research

Bloomers. No not the clothing variety, but the group described by Christine Fountain and colleagues* (open-access) in their paper on developmental trajectories in autism covered in this post. The bloomers grouping describing a specific group of children with autism who "experienced rapid gains, moving from severely affected to high functioning".

Crateva religiosa @ Wikipedia  
The whole idea of looking at children in the here and now and trying to predict where they will be in X years time seems to be gaining some ground in autism research circles.

The paper by Katherine Gotham and colleagues**, she of the revised algorithm*** for everyone's best loved gold standard autism assessment instrument, the ADOS, joins the crystal-ball reading, based as one might expect on longitudinal ADOS scores.

In brief:

  • The aim was to plot developmental trajectory in cases of autism. The hypothesis: "a substantial minority of children will show marked changes in ASD severity over time, with “Improvers” demonstrating the highest mean baseline and rate of growth in verbal IQ (VIQ)". The speculation: a link between autism 'functioning' and verbal intelligence, accepting that functioning means different things to different people.
  • Quite a large group of children (N=345) were examined, with at least one 'estimate' of an autism diagnosis at some point between the ages of 2 - 15 years and who received more than one ADOS session.
  • Results: move over Christine Fountain and your six developmental trajectories, Gotham et al describe a statistical model made up of 4 classes which best represented the observed data.
  • The majority of participant stuck to their allocated class based on severity of symptoms according to ADOS, although participants allocated to two of the classes showed increasing and decreasing severity of symptoms over development. As hypothesised, verbal intelligence was an important factor in predicting class membership increasing "at the greatest rate in the improving class".
  • Discussions start to turn to a possible role for trajectories in terms of endophentotypes and further delineation of the autism spectrum.

Once again, I'm really quite interested in this research and indeed this whole area of investigation. I've kinda said it before about how autism is, in some cases, actually quite an unstable diagnosis and how, given this instability combined with the heterogeneity and elevated risk for comorbidity noted across the autism spectrum, we need to find new ways to look at autism research outside of just an autism diagnosis as a starting point. In that respect it's good to see that people are starting to look into this issue (and not just the MIND Institute and their Autism Phenome Project).

Using ADOS to measure symptoms longitudinally is by no means a new phenomenon as per other articles from the authorship team such as this one from Lord and colleagues**** who reported again on four trajectory classes and again highlighted verbal ability as being involved. Elizabeth Pellicano***** likewise reported on developmental trajectory (using ADOS) and also detailed instances of 'diagnostic discontinuity'.

The suggestion that verbal intelligence might be a key part of predicting where a child with autism might be in X years time is also not a new concept. Gillespie-Lynch and colleagues****** (open-access) followed twenty participants with autism from child- to adulthood suggesting that "both early childhood language and RJA [responsiveness to joint attention] predicted adult social functioning". I'm sure that the movers and shakers of the new DSM-V 'social affect' bundling  with autism in mind were very happy to read this. Language and verbal intelligence it appears are pretty crucial to how autism progresses, bearing in mind what is known about verbal intelligence outside of autism.

There's not too much more to add to this post and topic of investigation. I should perhaps mention that when we talk about bloomers and improvers with autism spectrum disorders in mind, there is still a little bit of a gap as to the potential effects from intervention on certain cases. Research which I have been involved with for example, suggested that ADOS scores can also change alongside the adoption of dietary intervention at least in some cases of autism. I hold back from saying that this is 'proof' of any change in clinical presentation, but one does wonder exactly what effects interventions like those based in education or behavioural programs (early intervention?) might have for the current studies in this area.

Oh, and the idea that autism is actually autisms...

To finish, a spot of the fiddles is in order as Bellowhead go Ten Thousand Miles Away. Land ho!

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* Fountain C. et al. Six developmental trajectories characterize children with autism. Pediatrics. 2012; 12: e1112-20.

** Gotham K. et al. Trajectories of autism severity in children using standardized ADOS scores. Pediatrics. October 2012.

*** Gotham K. et al. The Autism Diagnostic Observation Schedule: revised algorithms for improved diagnostic validity. J Autism Dev Disord. 2007; 37: 613-27.

**** Lord C. et al. Patterns of developmental trajectories in toddlers with autism spectrum disorder. J Consult Clin Psychol. 2012; 80: 477-489.

***** Pellicano E. Do autistic symptoms persist across time? Evidence of substantial change in symptomatology over a 3-year period in cognitively able children with autism. Am J Intellect Dev Disabil. 2012; 117: 156-166.

****** Gillespie-Lynch K. et al. Early childhood predictors of the social competence of adults with autism. J Autism Dev Disord.  2012; 42: 161-174.


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ResearchBlogging.org Gotham, K., Pickles, A., & Lord, C. (2012). Trajectories of Autism Severity in Children Using Standardized ADOS Scores PEDIATRICS, 130 (5) DOI: 10.1542/peds.2011-3668