On autism and exposure to fragranced consumer products

The findings reported by Anne Steinemann [1] tap into an important issue seemingly relevant to many people diagnosed with autism or an autism spectrum disorder (ASD): exposure to various fragranced products such as air fresheners, deodorants and perfumes can seemingly cause various adverse physiological reactions. I know to some people this might not seem like particularly groundbreaking research, but when you read that almost 60% of autistic adults have been reporting "lost workdays or lost a job, in the past year, due to fragranced product exposure in the workplace" it kinda turns into something a lot more important.

Steinemann reports results across various different geographical cohorts pertinent to "the effects of fragranced products on autistic individuals ages 18–65 in the United States, Australia, and United Kingdom." This was a questionnaire-based study, a "web-based" survey, "part of the SSI [Survey Sampling International] web-based panel." The numbers included for study are in the thousands, with some 4% reporting "medically diagnosed autism" upon which the Steinemann study is based.

The conclusion: "83.7% report adverse health effects from fragranced products." Said effects included "migraine headaches (42.9%), neurological problems (34.3%), respiratory problems (44.7%), and asthma attacks (35.9%)." Further: "Health problems can be severe, with 74.1% of these effects considered potentially disabling under legislation in each country."

As you can perhaps see, exposure to fragranced products is potentially an important issue for many people on the autism spectrum. The Steinemann results are based on discussions with adults (18-65 years) but I daresay there may be much to see with younger cohorts too. I'd also be interested to see whether issues like comorbidity potentially over-represented alongside autism might also exert something of an important effect too.

Solutions? Well, I don't think it's too much to ask if public and workplaces could perhaps look at some of their spaces with a view to reducing their use of fragranced products. If for example, this means cutting back on things like those automated air fresheners that periodically squirt out a cloud of smelly stuff, I'm pretty sure quite a few more people - more than just autistic people - would benefit. Indeed, with all the focus on 'autism hours' these days, I wonder if this could be something to add to the list of being 'autism-friendly'? As for personal scented products and the like, well, if you know that you're going to be interacting with autistic people who might be particularly sensitive to fragrances, how about giving those scented products a miss for that day? I promise that you will still smell OK. I don't think these are unreasonable requests.

Then the next question: why? Why do such symptoms come about and what are the biological mechanism through which such 'sensitivity' occurs? Well, it appears that Steinemann has some research history when it comes to fragrances and autism [2] albeit looking at "the neuromodifications of three selected fragrances on male and female human fetal brain neurons." Oxytocin and arginine vasopressin were the molecular targets in that study. Whether there may be more to see from these compounds in relation to fragrance sensitivity in adults is a question to ask. Such issues also perhaps overlap with other research talking about olfaction and autism (see here and see here). I'm also minded to point readers in the direction of another condition/set of symptoms that could be relevant: multiple chemical sensitivity (MCS). Yes, yes, I know that MCS is disputed in some quarters, even to the point of mentioning the word 'psychosomatic' on some occasions [3], but it strikes me that such high rates of 'fragrance intolerance' in relation to autism *could* also be tied into the presentation of MCS. And such high numbers reporting such an intolerance is probably not just 'all in the mind'.

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[1] Steinemann A. Fragranced consumer products: effects on autistic adults in the United States, Australia, and United Kingdom. Air Quality, Atmosphere & Health. 2018; 10: 1137-1142.

[2] Sealey LA. et al. Environmental factors may contribute to autism development and male bias: Effects of fragrances on developing neurons. Environ Res. 2015 Oct;142:731-8.

[3] Jimenez XF. et al. Polyallergy (Multiple Chemical Sensitivity) is Associated with Excessive Healthcare Utilization, Greater Psychotropic Use, and Greater Mental Health/Functional Somatic Syndrome Disorder Diagnoses: A Large Cohort Retrospective Study. Psychosomatics. 2018 Aug 2. pii: S0033-3182(18)30418-3.

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Diagnosing autism: not to be sniffed at

All rights to Rozenkrantz et al (2015)

'Sniffing could provide autism test' went the BBC headline as the work of Liron Rozenkrantz and colleagues [1] (open-access available here) provided some media fodder and with it ideas "implying a mechanistic link between the underpinnings of olfaction and ASD [autism spectrum disorder] and directly linking an impaired IAM [internal action model] with impaired social abilities."

Looking at the sniff response in 36 children - 18 with autism and 18 asymptomatic (typically developing, TD) - researchers created a wonderful contraption comprising of "a custom-designed double-barreled pediatric nasal cannula that both delivered odors from a computer-controlled air-dilution olfactometer and measured the nasal airflow of the sniff response." With all credit to the authors, the attached picture to this post gives you an idea of what it looked like and how the red tube carried various odours up the nose, and the green tube measured changes in breathing patterns.

Researchers reported that the sniff response - whether or not we take a big sniff of nice smells or a not-so-big sniff of not-so-nice smells - was altered in the group comprising children with autism. "TD children altered their sniff to account for odorant properties within 305 ms of sniff onset." But: "ASD children had a profoundly altered sniff response, sniffing equally regardless of odor valance." So even when faced with the smell of sour milk or rotting fish against more pleasant odours of rose or shampoo, children with autism did not seem to modulate their sniffing behaviour.

"These results imply an altered olfactory response that is evident in children with ASD and is more pronounced with increased autism severity." Bearing in mind the small participant numbers, the results of the sniffing test seemed to tally with some of the ADOS scores obtained for participants as a marker for autism severity; specifically: "the sniff response remained highly predictive of the social affect component of ADOS."

These are interesting results calling out for further [independent] replication. The idea that the 'nose knows' with autism in mind is not necessarily a new one (see here) but put in the context of a potential biological tests for at least some autism, should be investigated further.

Music: Guns N' Roses - Sweet Child O' Mine.

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[1] Rozenkrantz L. et al. A Mechanistic Link between Olfaction and Autism Spectrum Disorder. Current Biology. 2015. 2 July.

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Rozenkrantz, L., Zachor, D., Heller, I., Plotkin, A., Weissbrod, A., Snitz, K., Secundo, L., & Sobel, N. (2015). A Mechanistic Link between Olfaction and Autism Spectrum Disorder Current Biology DOI: 10.1016/j.cub.2015.05.048

Synaesthesia prevalent in autism?

The BBC headline 'Study links synaesthesia to autism' recently caught my eye (and nose!) discussing the paper by Baron-Cohen and colleagues* (open-access) who suggested that: "The rate of synaesthesia in adults with autism was 18.9% (31 out of 164), almost three times greater than in controls".

Colour and sensation @ Wikipedia 

Synaesthesia according to the UK Synaesthesia Association is best described as a "union of the senses" whereby "two or more of the five senses that are normally experienced separately are involuntarily and automatically joined together".

In other words, some people might experience certain words as tastes or see colours when they hear music. The BBC follow-up their coverage of the Baron-Cohen paper with a story about a man who can taste the London Underground map and his efforts to re-design the Tube map according to 'sausage and eggs' and 'putrid meat'.

In their paper, the authors tested the suggestion of overlap between autism - adults with "high-functioning autism or Asperger's syndrome" - and synaesthesia by asking participants with autism and asymptomatic controls to complete a questionnaire on any experiences of synaesthesia alongside something called the Test of Genuineness-Revised (ToG-R) "to validate any self-reported auditory-visual forms of grapheme-colour (GC) and sound-colour (SC) synaesthesia and was sent to all participants in order to detect true and false positives and negatives". That being said, response rates to the ToG-R were not brilliant; as per another quote: "Telephone follow-up to find out why ToG-Rs were not being completed revealed that participants with autism reported fatigue from the 241 possible choices".

Based on their data however, they report that "The rate of synaesthesia in autism (18.9%) was almost three times greater than in the typical sample (7.22%)". They also suggest that this figure might be an under-estimate given that some participants with autism "claimed they did not have synaesthesia, but were judged by the experimenters to have synaesthesia on the basis of their questionnaire responses".

I have to say that I'm very interested in these results. Sensory issues with regards to the autism spectrum are something of growing importance given the effect that they can have on both how a person perceives the world around them and also how such perceptions can impact on day-to-day functioning and quality of life. Even the latest version of DSM saw fit to include sensory issues in their latest redefinition of the autism spectrum (see here).

That being said I still want to see more on this topic done before I totally commit to the likelihood that synaesthesia is frequently prevalent in cases of autism. Questions about how representative these results are for example, to those who present with a greater severity of autistic symptoms or with comorbid learning disability remain as does the question of mechanism and whether there are genetic or biological commonalities to be seen.

I'd also hazard a guess that synaesthesia is just the tip of the iceberg when it comes to sensory and visual issues and autism; indeed whether as per the exclusion criteria for acquired synaesthesia in the Baron-Cohen study "the person had any medical conditions affecting vision". Well, if the Ikeda results are anything to go on, yes would probably be the answer for anything up to 40% of those with autism. How such vision issues would impact on the presentation of synaesthesia remains to be seen. And finally there is the question of whether any other -sia conditions also reported in cases of autism might also show some involvement, as per the chatter about prosopagnosia (face-blindness)?

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* Baron-Cohen S. et al. Is synaesthesia more common in autism? Molecular Autism 2013, 4:40

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Simon Baron-Cohen, Donielle Johnson, Julian Asher, Sally Wheelwright, Simon E Fisher, Peter K Gregersen, & Carrie Allison (2013). Is synaesthesia more common in autism? Molecular Autism, 4 DOI: 10.1186/2040-2392-4-40

Gustational sensitivity and autism: a matter of taste

A sensory friend @ Paul Whiteley

Given the all-but accepted revisions for diagnosing autism spectrum conditions in DSM-5, there is one area of change to the Diagnostic & Statistical Manual entry that I think most people would be satisfied with: the overt inclusion of criteria surrounding unusual reactivity/interest to sensory input or sensory aspects of the environment.

Indeed whilst such sensory - perceptual issues in cases of autism have been known about for some years, many people (including me) have probably wondered to themselves why has it taken so long for this important factor for many people with autism to be included as part of the way the condition is assessed and diagnosed. Well now it is.. or at least will be fairly soon, minus any last minute changes that is.

Having said all that, just because such sensory issues are to be included in the diagnostic text, doesn't mean there is necessarily any consensus on what can be done about them as and when required, as per the recent policy statement by the American Academy of Pediatrics* (full-text).

I digress.

You could literally write a whole book about sensory issues in relation to autism - indeed some people have - but for this post, I'm zooming in on one part of that sensory issue dealing with taste or to use the proper scientific term, gustational sensitivity. I'm also sticking with the term 'sensitivity' in this post as per the assumption that some people on the autism spectrum seem to be particularly sensitive - hypersensitive - to certain types of taste and acknowledging also the opposing result, hyposensitivity to be also potentially present. I hasten to add that everyone, whether autistic or not, has their own individual tastes, likes and dislikes; taste is a very personal thing as per the various discussions on phenylthiocarbamide (PTC) perception which some may remember with regards to 'diagnosing' schizophrenia.

I remember about 15 years ago seeing gustational sensitivity in action with a child with autism. It was during a visit to see a child involved in one of our early research studies to talk to the parents about the food and feeding patterns they were seeing. The child was thirsty and mum brought a drink of cordial for the child. The drink seemed pretty concentrated and when asked about this, mum replied something along the lines of "XX always likes lots of cordial". Indeed not being a connoisseur of cordial drinks, even I could see that there was more cordial than water. That drink would probably have been pretty strong. Such observations have been accompanied by other anecdotal reports of preferences for strong tasting foods in cases of autism. I hasten to add however that not everyone with autism can be found tucking into a vindaloo curry at every opportunity for example, as per this abstract from IMFAR 2012.

Research into the gustational aspects to some cases of autism is still quite thin on the ground. It all really kicked off in the early noughties with this study** by quite a familiar name, Sally Rogers (and colleagues) who noted some interesting differences in parent reported sensory symptoms in children with autism. Taste and smell seemed to show the greatest difference in autism compared with cases of developmental delay, Fragile X syndrome and asymptomatic controls. Sample sizes were relatively small but the results were interesting.

Sue Leekam and colleagues*** (previously from Durham University just down the road from me) were among other groups to further categorise sensory issues in cases of autism; again, with specific reference to smell and taste. This paper by Bennetto and colleagues**** (full-text) put some 'meat on to the bones' with their characterisation of taste (sweet, salty, sour & bitter) perception in autism. I note also reference to a bit of a blast from the past with the use of 'Sniffin' sticks'.

A couple of more papers to mention then I'm finished. This paper by Lane and colleagues***** (including another familiar name, Manya Angley) looked at the possibility of subtyping children with autism on the basis of sensory processing including category headers like taste and smell. And finally, Tavassoli and Baron-Cohen****** add to the evidence base on issues with taste in adults with autism.

From this and other evidence, both scientific and from lay sources, it is fairly clear that at least some people on the autism spectrum seem to present with issues related to the sensory aspects of taste. I've not really talked about related issues such as smell, texture (food texture) and issues like pica which seem also to be related to gustation but nevertheless one needs to bear these in mind also.

The mechanism is still unclear as to why taste perception might be attenuated for some people, accepting that personal preference should not be excluded from any explanation and the realisation of some degree of inter-relatedness between the various senses we all use. I could speculate on one possible mechanism of effect although with the caveat that lots of processes will most likely be (variably) involved, including some recent suggestion of more physiological issues potentially present as per the article from Betalli and colleagues****** (which probably deserves a blog post on its own).

To finish, taste can mean more than one thing; and to show that I have very little of it when it comes to fashions and trends, and in honour of this years Eurovision... whatever it was, nul points for Jemini back in 2003. (Bravo to the Hump for not coming last).

P.S. The hedgehog picture was taken a few nights back outside my house as the little critter was foraging for some tasty earthworms in the garden.

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* Sensory Integration Therapies for Children With Developmental and Behavioral Disorders.
Section on complementary and integrative medicine; Council on children with disabilities.
Pediatrics. May 2012

** Rogers SJ. et al. Parent reports of sensory symptoms in toddlers with autism and those with other developmental disorders. JADD. 2003; 33: 631-642.

*** Leekam SR. et al. Describing the sensory abnormalities of children and adults with autism. JADD. 2007; 37: 894-910.

**** Bennetto L. et al. Olfaction and taste processing in autism. Biological Psychiatry. 2007; 62: 1015-1021.

***** Lane AE. et al. Sensory processing subtypes in autism: association with adaptive behavior. JADD. 2010; 40: 112-122.

****** Tavassoli T. & Baron-Cohen S. Taste identification in adults with autism spectrum conditions. JADD.  October 2011.

******* Betalli P. et al. Autism and esophageal achalasia in childhood: a possible correlation? Report on three cases. Diseases of the Esophagus. May 2012
DOI: 10.1111/j.1442-2050.2012.01358.x