Interoception and body awareness in autism

"Interoception: the sense of the physiological condition of the body" [1].

This was an important concept detailed in the paper by Lisa Fiene and Charlotte Brownlow [2] with autism in mind. Looking at how adults diagnosed with an ASD (autism spectrum disorder) "interpret elements of the interoceptive sense, which includes thirst, hunger, temperature, satiety" researchers questioned those on the spectrum (n=74) and asymptomatic controls (n=228) with "self-reported perceptions of body awareness... and thirst awareness" in mind.

Based on data derived from the Body Awareness Questionnaire (BAQ) and Thirst Awareness Scale (TAS), a lower level of of body and thirst awareness was reported for the autism group. Indeed, authors reported "a large effect" when it came to the differences between the groups. Ergo: "difficulty with sensing internal bodily states could theoretically impact on the physical and mental health, social interactions and self-awareness of adults with ASD."

These are potentially very important results. Allowing for the fact that self-report measures were used and that those towards the more 'able' end of the autism spectrum were only included for study, the idea that basic sensations such as hunger and thirst might not always be sensed and acted upon by some on the autism spectrum is a little worrying.

Outside of the reports of issues with response to temperature noted for some on the autism spectrum which may fall into the area of altered interoception, the idea that thirst, hunger and satiety mechanisms might also show some alteration for some potentially taps into quite a few other areas too. One might for example, entertain the idea that issues with interoception might tie into the growing evidence base looking at feeding practices and weight issues with autism in mind (see here), accepting that feeding practices/habits are probably not the only variable related to weight issues (see here). I wonder also if the reported issues with the hormone ghrelin in cases of autism might also show some involvement too (see here). Polydipsia - excessive thirst - also has some research history with autism in mind (see here) that might also require a little more investigation. Examining the issue of interoception and autism with the various sensory issues linked to the diagnosis (see here) is probably a good idea.

Music: Foals - Spanish Sahara.

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[1] Craig AD. How do you feel? Interoception: the sense of the physiological condition of the body. Nature Reviews Neuroscience. 2002; 3: 655-666.

[2] Fiene L. & Brownlow C. Investigating interoception and body awareness in adults with and without autism spectrum disorder. Autism Res. 2015 Mar 25.

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Fiene L, & Brownlow C (2015). Investigating interoception and body awareness in adults with and without autism spectrum disorder. Autism research : official journal of the International Society for Autism Research PMID: 25808391

Altered ghrelin levels in boys with autism

"Honey, it's the '90s, remember?"

Saudi Arabia and autism research? It must be at least one author from the research tag-team that is Mostafa and Al-Ayadhi.

Indeed, in today's post it is Laila Al-Ayadhi featured on the paper by Felwah S. Al-Zaid and colleagues [1] (open-access) who concluded on: "a potential role for the hormone ghrelin in the pathogenesis of autism".

Ghrelin, by the way, is often called the 'hunger hormone' as a result of its effects in relation to energy homoeostasis. Alongside another hormone called leptin (which has also been implicated in cases of autism) the long-and-short of food intake regulation seem to be covered by these hormones [2].

The Al-Zaid paper is open-access but I'll direct you to a few important points...

• A case-control study, authors looked at various measures for 31 boys diagnosed with autism compared with 28 age- and sex-matched controls.
• Alongside various anthropometric measures, plasma and serum levels of "acyl ghrelin (AG), des-acyl ghrelin (DG), total testosterone (TT), free testosterone (FT), leptin and growth hormone (GH)" were measured. These were single spot measures with samples taken "after an overnight fast". 
• Results: the autism group were on average heavier than controls but aside from that, no other physical measure was significantly different (mean height was greater in the autism group but just escaped significance). Both acyl ghrelin and des-acyl ghrelin levels were significantly lower in the autism group. By contrast, leptin levels were higher in the autism group (as per other independent findings) and free and total testosterone levels were significantly elevated compared to controls. Taking into account the effect of weight and it's link to adiposity, authors also showed that an analysis of a smaller subgroup (autism, n=27; controls, n=28) where mean weight was controlled for, found a similar trend in hormone levels (see this link to Table 3 of the paper) bearing in mind how body fat can influence the parameters.
• Various correlational analyses were completed on the data but given the relatively small participant groups and the use of spot samples I'm not particularly minded to read too much into these findings at this time.
• The authors conclude that their study: "contributes significantly to the understanding of hormonal dysregulation in the pathophysiology of autism, as it provides baseline data regarding hormonal profiles in autism and substantiates potential clinical interventions".

Small participants numbers and a "lack of female subjects with autism" kinda prohibit me from reading too much into these findings as they stand. I've already made mention of the research trend when it comes to elevated leptin levels and autism (see the paper from Rodrigues and colleagues [3] as one example). Likewise, testosterone levels and autism have received quite a bit of autism research attention down the years (see here). Indeed, elevations in testosterone levels not described in-utero with some potential relationship to foetal programming, has been the stuff of controversy in autism research circles [4].

Going back to the primary ghrelin findings and the observations of lower levels detected in their autism group, the authors speculate on some of the hows and whys of their findings. Gastrointestinal (GI) issues get a call-out and how some of the variety of GI issues noted in cases of autism "could affect the gastric mucosa and interfere with the normal function of ghrelin-secreting cells". although no particulars about GI issues are included in their descriptions of their cohort. One additional issue that I would perhaps add to the whole inflammation, dysbiosis et al discussions would be how ghrelin seems to play some role in GI motility [5] too. That being said, 'wide-ranging' is perhaps the best way to describe what biological processes ghrelin might impact on [6].

I was a touch surprised that the more usual role for ghrelin in terms of hunger and energy homoeostasis was not given more prominence in the Al-Zaid article on autism. Food and feeding patterns are important topics when it comes to autism as per discussions on the extremes sometimes noted in cases of autism (see here) and the increasingly important issue of weight (see here) (which also seemed to be picked up in the authors' findings). One might speculate that hunger and signals linked to hunger might be similarly tied into at least some of the feeding issues reported in autism?

As I seem to do in many discussions these days, I'll reiterate that there is quite a bit more to see and do in research terms on the relationship between ghrelin and related hormones and autism. The additional suggestion from Ghanizadeh [7] about the ghrelin being a "promising therapeutic target for co-occurring autism and epilepsy" might also be worthy of greater inspection.

Music to close. Iggy Pop and Lust for Life.

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[1] Al-Zaid FS. et al. Altered ghrelin levels in boys with autism: a novel finding associated with hormonal dysregulation. Sci Rep. 2014 Sep 26;4:6478.

[2] Klok MD. et al. The role of leptin and ghrelin in the regulation of food intake and body weight in humans: a review. Obes Rev. 2007 Jan;8(1):21-34.

[3] Rodrigues DH. et al. Changes in Adipokine Levels in Autism Spectrum Disorders. Neuropsychobiology 2014;69:6-10

[4] Geier DA. & Geier MR. A prospective assessment of androgen levels in patients with autistic spectrum disorders: biochemical underpinnings and suggested therapies. Neuro Endocrinol Lett. 2007 Oct;28(5):565-73.

[5] Greenwood-Van Meerveld B. et al. Ghrelin as a target for gastrointestinal motility disorders. Peptides. 2011 Nov;32(11):2352-6.

[6] Delporte C. Structure and physiological actions of ghrelin. Scientifica (Cairo). 2013;2013:518909.

[7] Ghanizadeh A. Ghrelin as a promising therapeutic target for co-occurring autism and epilepsy. Epilepsy Behav. 2011 Feb;20(2):420-1.

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Al-Zaid FS, Alhader AA, & Al-Ayadhi LY (2014). Altered ghrelin levels in boys with autism: a novel finding associated with hormonal dysregulation. Scientific reports, 4 PMID: 25257829