Sensory processing issues are present throughout the autism spectrum

I want to make an initial point about the paper by Corentin Gonthier and colleagues [1] and their research findings titled: 'Sensory Processing in Low-Functioning Adults with Autism Spectrum Disorder: Distinct Sensory Profiles and Their Relationships with Behavioral Dysfunction', I'm not a great fan of the use of the term 'functioning' when it comes to autism.

Yes, I know what message it's trying to convey in terms of 'severity' of autism and/or accompanying learning (intellectual) disability and/or the level of day-to-day adaptive skills a person possesses with the aim of providing some indication of how 'able' or 'disabled' they are. My issue, and indeed I'm not the only one with a bee in their bonnet about this, are that the terms 'low functioning' and 'high functioning' rarely provide an accurate portrayal of the cumulative aspects of a person. One example of this can be seen in the quite depressing statistics when it comes to employment and autism, and how even those 'high-functioning' people on the spectrum, sometimes with above average intellect, are much less likely to be employed than their peers. High-functioning does not always mean 'can-function' in real life (even those with seemingly impressive skills) and importantly, tends to take little account of how comorbid issues such as anxiety can be so utterly disabling for a person.

I digress. The Gonthier study set about asking an important question about an important group: do the various sensory processing issues quite commonly reported in those on the more able side of the autism spectrum also extend to those peoples with more profound difficulties? Based on data "collected for a representative sample of inpatients in autism care centers (N = 148) and a non-clinical control group" researchers concluded that yes, sensory dysfunction is "highly prevalent in low-functioning adults with ASD [autism spectrum disorder]" but no, there is no 'one-size-fits-all' profile for this population. Indeed, that lack of a universal profile in the cohort studied pretty much mirrors what has been noted in  the 'more able' autism phenotype.

One other detail mentioned in the Gonthier findings also caught my eye in that sensory dysfunction "predicts specific patterns of behavioral disorders" at least in this cohort. This is an intriguing suggestion that potentially amongst the myriad of issues falling under the heading of 'challenging behaviours' for example, there may be a role for sensory processing issues too. It does kinda make sense that sensory issues could invoke some of those so-called challenging behaviours allied to other research looking, for example, at how pain might manifest among some of those on the autism spectrum (see here). It also makes for an even stronger case that screening for the presence of ophthalmic issues as one potential source/complication of those sensory issues should be more widely indicated irrespective of where someone lies on the autism spectrum (see here) (and whatever description you use of their place on the spectrum).

But a lot more research is required on the topic of sensory processing issues, and indeed, covering the entire autism spectrum in line with other writings [2] ...

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[1] Gonthier C. et al. Sensory Processing in Low-Functioning Adults with Autism Spectrum Disorder: Distinct Sensory Profiles and Their Relationships with Behavioral Dysfunction. J Autism Dev Disord. 2016 Jun 30.

[2] Tager-Flusberg H. et al. Conducting research with minimally verbal participants with autism spectrum disorder. Autism. 2016 Jun 26. pii: 1362361316654605.

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Gonthier C, Longuépée L, & Bouvard M (2016). Sensory Processing in Low-Functioning Adults with Autism Spectrum Disorder: Distinct Sensory Profiles and Their Relationships with Behavioral Dysfunction. Journal of autism and developmental disorders PMID: 27364513

Autism: visual stress and coloured overlays?

The small study from Amanda Ludlow & Arnold Wilkins [1] is introduced for your reading pleasure today and the idea that "atypical sensory behaviours and symptoms of visual stress" were not uncommon features when it came to a diagnosis of autism and/or Tourette's syndrome (TS). As per that opening sentence, this was a small study - 12 children with autism, 12 children with TS and 12 controls - but that doesn't mean that the results might not be important...

So far you might be slightly underwhelmed by the idea that sensory issues (and onwards linked behaviours) might be over-represented when it comes to autism given what has already been talked about for quite a few years. But... following the introduction of a colour overlay (a coloured plastic sheet placed over text) supposedly thought to reduce visual stress, for at least for some children with autism there seemed to be some potential effects noted: "Four of the 12 children with ASD [autism spectrum disorder] and none of the control children read over 15% more quickly with an overlay." The test by the way, used to assess reading performance was the Wilkins Rate of Reading Test designed by one of the authors.

I'm interested in these findings. In one of the earliest posts on this blog, I discussed the idea that visual perceptual issues accompanying a diagnosis of autism might, to some extent, be 'countered' via the use of coloured overlays or tinted glasses (sometimes called Irlen lenses) (see here). Alongside a few quite well-known people on the autism spectrum using such visual aids, there is quite an appetite for this type of approach here in Blighty as for example, per the writings and practice of people such as Ian Jordan. Accepting that the plural of anecdote is not data, I've seen Ian talk about his work, and some of the case studies are really rather interesting including the possibility of a link between vision and coordination.

A quick scan of the other peer-reviewed literature in this area suggests that Ludlow & Arnold are no strangers to this potentially important area of autism research although quite a bit more needs to be done with regards to effectiveness and perhaps identify those potential 'best responders' to this type of approach. I might also suggest that said investigations might also benefit from some good old-fashioned ophthalmic inquiry too given what is starting to be understood about eye pathology and autism (see here).

I appreciate that talk of Irlen lenses and coloured overlays may not be everyone's cup of tea in light of the various 'discussions' these interventions have had when it comes to the diagnosis of dyslexia down the years. Yes, science definitely needs to come before any big claims are made or marketed. But the idea that sensory issues might be a rather common occurrence in relation to autism and that vision in particular might be an important source of those sensory issues reported perhaps means that this research avenue should be more thoroughly explored given that there may be something that can be done to alleviate visual stress as and when it does occur.

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[1] Ludlow AK. & Wilkins AJ. Atypical Sensory behaviours in children with Tourette's Syndrome and in children with Autism Spectrum Disorders. Res Dev Disabil. 2016 Jun 7;56:108-116.

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Ludlow AK, & Wilkins AJ (2016). Atypical Sensory behaviours in children with Tourette's Syndrome and in children with Autism Spectrum Disorders. Research in developmental disabilities, 56, 108-116 PMID: 27286465

Vision impairment and ADHD?

Science often has the ability to surprise.

So it was when I first read the paper by Dawn Decarlo and colleagues* (open-access here) which suggested that: "children with vision impairment may be more likely to be diagnosed with ADHD [attention deficit hyperactivity disorder] than children in the general population". I should point out that this observation should not be totally unexpected given some media for other studies by the authors (see here).

Lady in a green jacket @ Wikipedia  

The Decarlo study was based on a question of "whether the prevalence of parent-reported ADHD diagnosis in a cohort of pediatric low vision subjects was similar to that reported for the general population". It seems researchers were a little bit worried that there may be some mixing up of the signs and symptoms of possible ADHD as a consequence of a child's visual impairment and sought to further look into the issue.

So, bearing in mind the paper is open-access, a few study details:

• Alabama, USA was the study setting, and the medical records of participants (N=245) with low vision were drawn from two sites. Researchers garnered various details about participants covering basic demographic information and that relevant to vision including "primary ocular diagnosis, presence or absence of nystagmus, and best-corrected visual acuity in each eye". They also asked participants' parents whether or not their child had ever received a diagnosis of ADHD and had state and national ADHD prevalence estimates to hand.
• Results: the Alabama state ADHD prevalence estimate (based on 2007 data) was 14.3% and the US national prevalence 9.5%. The parent-reported prevalence rate of study children ever having a diagnosis of ADHD was 22.9% (56.245). Examination of an additional cohort of 19 children with almost total vision loss for a diagnosis of ADHD was 10%.
• Albinism - a condition concerned with the production of melanin - was the most frequently reported eye problem among participants (16%) and similar to the issue of optic nerve hypoplasia (ONH), saw a prevalence of ADHD diagnosis at 20% of these cases. Indeed, ONH has previously been linked with 'behavioural problems' in other research** and indeed, some of the features of autism***.
• Researchers concluded: "the prevalence of parent-reported ADHD among children with vision impairment in the present study is considerably higher than that reported by the Centers for Disease Control and Prevention".

There is obviously more to do in this area insofar as ascertaining whether these results are more widely applicable to cases of paediatric vision impairment or just a statistical blip. Noting for example, that the State of Alabama has an ADHD prevalence estimate some way above the US national estimate, might imply that ADHD is more generally apparent as a diagnosis there, so children were more likely to receive a diagnosis as a result of better screening facilities for example. Indeed, in my review of some of the [worldwide] prevalence rates of pediatric ADHD rates (see here), the figures coming back were nearer the US national average than the Alabama state estimate although potentially rising.

The lack of an external control group looking both at asymptomatic controls or even those children with something like hearing impairment in the Decarlo study, means that some caution must be exercised before leaning too far into the suggestion of any relationship.

The question of what mechanism might be behind any association is also important. I could suggest that the quite recent report of a link between solar intensity and ADHD (see here) might potentially offer some clues if one is to assume that vision is a common denominator across these areas of research. That being said, it is quite a tentative link and as yet, I can offer no further support for this suggestion.

Perhaps more relevant are the discussions about shared genetic/environmental influences which affect vision and potentially, risk of ADHD, as being linked to any association. Taking you back to the paper by Antoine and colleagues**** which was discussed in another post (see here) on inner ear conditions being linked to hyperactivity, one might assume similar mechanisms to be plausible. That also the paper by Kim and colleagues***** reported issues with vision function and colour vision to be linked with cases of adult ADHD is something else to throw into the mix.

Whatever the reason(s) for such a correlation, I am intrigued by the Decarlo findings and wait attentively for any further movement in this area of investigation.

Music to close, and having recently heard the song Purple Rain on the radio, I have a rekindled respect for Prince...

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* Decarlo DK. et al. Prevalence of attention-deficit/hyperactivity disorder among children with vision impairment. J AAPOS. 2014 Feb;18(1):10-4.

** Teär Fahnehjelm K. et al. Optic nerve hypoplasia in children and adolescents; prevalence, ocular characteristics and behavioural problems. Acta Ophthalmol. 2013 Oct 7.

*** Parr JR. et al. Social communication difficulties and autism spectrum disorder in young children with optic nerve hypoplasia and/or septo-optic dysplasia. Dev Med Child Neurol. 2010 Oct;52(10):917-21.

**** Antione MW. et al. A Causative Link Between Inner Ear Defects and Long-Term Striatal Dysfunction. Science. 2013; 341: 1120-1123.

***** Kim S. et al. Visual function and color vision in adults with Attention-Deficit/Hyperactivity Disorder. J Optom. 2014 Jan-Mar;7(1):22-36.

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Decarlo DK, Bowman E, Monroe C, Kline R, McGwin G Jr, & Owsley C (2014). Prevalence of attention-deficit/hyperactivity disorder among children with vision impairment. Journal of AAPOS : the official publication of the American Association for Pediatric Ophthalmology and Strabismus / American Association for Pediatric Ophthalmology and Strabismus, 18 (1), 10-4 PMID: 24568975