Sunday, 2 April 2017

On the under-studied populations within the autism spectrum

I don't typically post on a Sunday, but given that today - 2nd April - is World Autism Awareness Day I've decided to make an exception. The theme of today's post is based around the notion that the autism spectrum is truly wide and heterogeneous, and although this is fairly universally acknowledged, the current peer-reviewed research literature on autism is perhaps not yet so accepting. So...

Consistent with the idea that scientific research seems to go through cycles of themes/interests, the commentary paper by Bhismadev Chakrabarti [1] (open-access) continues an important theme talking about the representativeness of autism research (see here). Specifically how: "Research on the autistic phenotype has focused mostly on higher functioning individuals on the spectrum, neglecting those on the lower end."

OK, first things first. The idea of 'functioning' in relation to the autism spectrum is something that some people (including myself) find a little problematic. Yes, I know what it is trying to describe in terms of ability levels, adaptive skills and the level of support seemingly required as examples. But like many things when it comes to the autism spectrum, the [sweeping] generalisation that high-functioning autism automatically means 'can function' autism and low-functioning autism conversely means 'can't' doesn't really do justice to the complexity underneath such categorisations. I say all that acknowledging that no simple, viable alternative currently exists to replace 'functioning' at the present time.

Chakrabarti takes the reader through the issues of research representativeness based on the findings reported by Jack & Pelphrey [2] and their research review of neuroimaging studies in relation to autism. They concluded that: "There is a paucity of neuroimaging research on ASD [autism spectrum disorder] + ID [intellectual disability], ASD + MV [minimally verbal], and ASD + R [developmental regression], and what findings do exist are often contradictory, or so sparse as to be ungeneralizable."

I'm gonna pull out a couple of key points raised by Chakrabarti that are worthy of lots more research and clinical inspection.

First: "Should we be thinking of these different populations (MV, R and ID) as distinct subgroups within ASD?" Set within the context of 'the plural autisms' (see here) and how autism as a singular label seems to have very little usefulness as a research starting point (see here), it strikes me that Chakrabarti's suggestion of 'phenotypic dimensions' is quite a good one. The fact that developmental regression gets a look-in is also quite important (see here and see here) (no, not every single case of autism was present before or at birth/early infancy).

Second, on the question of 'neuroimaging phenotypes' akin to some of the parameters set out in the RDoC alternative to DSM (see here) I think we have to wait and see. From what we already know about neuroimaging results when it comes to the autism spectrum as a whole, there is no one 'brain area' seemingly linked to all diagnoses of autism (see here) as things currently stand, bearing in mind the limitations of the technology currently used. I don't doubt however that specific groups of people on the autism spectrum might be more likely to show definite collective brain pathology (see here) particularly where certain over-represented comorbidity might complete the clinical picture. The current state of findings in this area also has implications for the use of problematic terms such as 'neurotypical' to denote not-autism (I personally have no idea what neurotypical looks like on a brain scan nor in terms of development, behaviour, maturation or comorbidity).

I'm hoping that papers/commentaries such as the one from Chakrabarti are a call to action when it comes to making autism research 'work' for everyone on the autism spectrum. That and acknowledging that the existing - skewed - research base might be missing some important details when it comes to the very wide and very heterogeneous autisms...

To close and without getting too political, I want to link to a piece that was published in the Huffington Post this week (see here) discussing the idea of 'celebrating' world autism awareness day. It's something that I've seen quite a lot of these past years. Reiterating that the autism spectrum is indeed wide and heterogeneous, I found the article to very moving particularly the writer's notion that: "What I will do is celebrate my son for who he is... But I won’t celebrate the struggles we call autism." Appreciating that autism as a label is 'identity' for some on the spectrum, such sentiments reaffirm the requirement to ensure that all voices on the autism spectrum are heard, and that 'celebration' is reserved for people and their achievements, not their labels...

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[1] Chakrabarti B. Commentary: Critical considerations for studying low-functioning autism. J Child Psychol Psychiatry. 2017 Apr;58(4):436-438.

[2] Jack A. & A Pelphrey K. Annual Research Review: Understudied populations within the autism spectrum - current trends and future directions in neuroimaging research. J Child Psychol Psychiatry. 2017 Apr;58(4):411-435.

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ResearchBlogging.org Chakrabarti B (2017). Commentary: Critical considerations for studying low-functioning autism. Journal of child psychology and psychiatry, and allied disciplines, 58 (4), 436-438 PMID: 28346760