"Minor physical anomalies" and autism: hypermobility very much included

'Minor physical anomalies' (MPAs) are defined as "subtle, abnormal morphological features, such as deviations in morphology of the head, eyes, ears, mouth, hands, and feet." I appreciate that such a term is probably not going to everyone's cup of tea, but given the embryological links between organs such as the brain and skin, it's assumed that "MPAs may mirror altered brain development."

That was the starting point for the study results published by Lynnea Myers and colleagues [1] looking for the presence of MPAs in a cohort of over 110 twins, around half of whom had received a concordant or discordant neurodevelopmental disorder diagnosis such as "intellectual disability (ID), communication disorders, autism spectrum disorder (ASD), attention-deficit/hyperactivity disorder (ADHD), specific learning disorders, and motor disorders." Alongside various behavioural and diagnostic assessments, researchers also used a special MPA checklist "containing a total of 179 anomalies for males (24 body regions) and 171 for females (23 body regions)" with their cohort. This checklist also included various other 'issues' that are "commonly assessed for in physical exams."

Various results were produced bearing in mind the quite complicated participant mix included for study (i.e. presence or not of a neurodevelopmental disorder, concordance among twins, zygosity, specific neurodevelopmental diagnosis, etc). Autism was the only neurodevelopmental diagnosis that was "significantly associated with the extent of MPAs." If twins were concordant for autism or autism spectrum disorder (ASD), researchers observed that they "had descriptively the highest median (Md) number of MPAs." Where twins were discordant - one had autism, the other not - researchers still observed MPAs, albeit to a slightly lesser degree (number). Further: "The most common MPAs in participants with ASD included overweight (39%), hypermobility (36%), pes planus (29%), straight eyebrows (29%), vision impairment (25%; 29% of these with corrective lenses), arachnodactyly/long toes (25%), long eyelashes (21%), and microtia (21%)."

Putting to one side the important findings that almost 40% of those with ASD were described as overweight (see here) or that vision issues were present in a quarter (see here), I was drawn to the suggestion that quite a percentage of those with autism (36%) were described as having hypermobility. Hypermobility, where joints are more flexible than usual, in the context of autism is something of an interest of mine (see here and see here). Not least because it is an area of the autism research landscape crying out for a lot more investigation, both as part of a wider 'psychiatric picture' (see here) and also in the 'ESSENCE' context that autism rarely exists in some sort of diagnostic vacuum (see here).

Minus any sweeping generalisations, there are a few potentially important implications either linked to or arising from hypermobility in the context of autism. Poor balance and/or coordination is one possible outcome from hypermobility that would perhaps tie into what has been discussed in the autism research literature for years and years now [2] (even Kanner mentioned it). The observation that functional gastrointestinal (GI) issues such as constipation and diarrhoea also seem to be over-represented in relation to hypermobility [3] also potentially accords with findings pertinent to quite a lot of autism (see here) (bearing in mind that I'm not saying that all bowel issues noted in autism are necessarily hypermobility-connected). If however one was to stretch things further, one might be looking at something like joint hypermobility in the context of connective tissue disorder and what that could mean for something like intestinal permeability issues associated with 'some' autism (see here). I know this is speculative, but at least it provides a research plan of action to include in future investigations in this area.

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[1] Myers L. et al. Minor physical anomalies in neurodevelopmental disorders: a twin study. Child and Adolescent Psychiatry and Mental Health. 2017; 11: 57.

[2] Cassidy S. et al. Dyspraxia and autistic traits in adults with and without autism spectrum conditions. Mol Autism. 2016 Nov 25;7:48.

[3] Fikree A. et al. Functional gastrointestinal disorders are associated with the joint hypermobility syndrome in secondary care: a case-control study. Neurogastroenterol Motil. 2015 Apr;27(4):569-79.

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Low muscle tone and autistic traits

"This large study showed a prospective association of infant muscle tone with autistic traits in childhood."

So said the findings reported by Fadila Serdarevic and colleagues [1] who, looking at nearly 3000 children, were able to assess early motor development and muscle tone "between ages 2 and 5 months" and later parental ratings of autistic traits in children at 6 years of age. Said autistic traits were surveyed using the "the Social Responsiveness Scale (SRS) and the Pervasive Developmental Problems (PDP) subscale of the Child Behavior Checklist." Authors concluded that there was something of a connection between low muscle tone and autistic traits: "Low muscle tone in infancy predicted autistic traits measured by SRS... and PDP" and further: "early detection of low muscle tone might be a gateway to improve early diagnosis of ASD [autism spectrum disorder]."

Just before anyone gets ahead of themselves with this data, it is worth pointing out that despite the large participant group included for study and the prospective nature of the study design, this was a study only really looking at two sets of variables across quite a long time-frame. It's not beyond the realms of possibility that other factors might influence the presentation of [parent-reported] autistic traits outside of just early measures of muscle tone or anything related...

But let's set this research in some context. Muscle tone in a broader sense had been noted to be potentially 'linked' to autism in some of the earliest texts on the topic (see here). More recent discussions on how motor skill in the context of gait for example, might be something important to at least some autism (see here) add to the relevance. One might also look to the some of the typical reasons why low muscle tone (hypotonia) may present to see whether there are areas that could inform autism research too. I note for example, mention of Ehlers-Danlos syndrome (EDS) in some of the texts and this would perhaps appeal to further investigation on any overlap between EDS (or other connective tissues disorders) and autism (see here). Serious infections such as encephalitis and meningitis have also been mentioned in the context of hypotonia, and again, might be indicated in relation to hypotonia and some autism (see here). There is also a possibility that hypotonia could (in some cases) be tied into mitochondrial disease; something else that could be relevant to at least some 'types' of autism (see here). All of these areas are worthy of further research inspection added to the idea that muscle tone might be rather more core to autism than many people might appreciate.

'And the best picture goes to'...

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[1] Serdarevic F. et al. Infant muscle tone and childhood autistic traits: A longitudinal study in the general population. Autism Res. 2017 Feb 9.

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Serdarevic F, Ghassabian A, van Batenburg-Eddes T, White T, Blanken LM, Jaddoe VW, Verhulst FC, & Tiemeier H (2017). Infant muscle tone and childhood autistic traits: A longitudinal study in the general population. Autism research : official journal of the International Society for Autism Research PMID: 28181411

Joint hypermobility and links to psychiatry

"The relationship between JH/HDCT [joint hypermobility / heritable disorders of connective tissue] and mental disorders merits further attention in order to improve current knowledge and clarify a possible common etiology."

There is nothing in the desert and no man needs nothing.

That was the conclusion reached in the paper by Carolina Baeza-Velasco and colleagues [1] looking at the possibility of some interesting connections, outside of just physical presentation, when it comes to the range of conditions headed under the label 'disorders of connective tissue'. The list of diagnoses potentially 'associated' with JH/HDCT by Baeza-Velasco et al is pretty long: "anxiety disorders, depression, schizophrenia, neurodevelopmental disorders (autism, attention deficit/hyperactivity disorder [2], and developmental coordination disorder), eating disorders, personality disorders and substance use/misuse."

From the point-of-view of this blog, mention of the word 'autism' is perhaps the most important suggested link, harking back to some previous discussion of joint hypermobility and gait with the autism spectrum in mind (see here). I'm still pretty interested in seeing this issue followed up in the autism research arena bearing in mind the possible influence of comorbidity as per findings related to the presence of anxiety and joint hypermobility [3] and the question of which comes first: autism or hypermobility?

Music: Glow by Ella Henderson.

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[1] Baeza-Velasco C. et al. Joint hypermobility and the heritable disorders of connective tissue: clinical and empirical evidence of links with psychiatry. Gen Hosp Psychiatry. 2014 Oct 16. pii: S0163-8343(14)00264-3.

[2] Baeza-Velasco C. et al. Connective tissue problems and attention deficit and hyperactivity. ADHD Attention Deficit and Hyperactivity Disorders. 2014. 1866-6647

[3] Sanches SB. et al. Anxiety and joint hypermobility association: a systematic review. Rev Bras Psiquiatr. 2012 Jun;34 Suppl 1:S53-60.

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Baeza-Velasco C, Pailhez G, Bulbena A, & Baghdadli A (2014). Joint hypermobility and the heritable disorders of connective tissue: clinical and empirical evidence of links with psychiatry. General hospital psychiatry PMID: 25459977

Joint hypermobility

Take a look at the picture in this post taken from this link describing joint hypermobility on the NHS Choices website. Notice the unusual orientation of the thumb in the picture, something that most of us would be unable to do without at least having a rather painful broken thumb. This is one example of joint hypermobility, where joints are able to stretch further than normal.

Source: NHS Choices website

I don't know about you but I had several contortionists in the making in my classes at school. Kids who were pretty well versed in showing off their hypermobile joints (often to the detriment of us not so talented children). Not surprisingly these were probably the same kids who easily perfected 'the caterpillar' and similar electric boogaloo moves whilst the rest of us ended up just doin' the slug.

It is probably not surprising that quite a few of the population possess at least one hypermobile joint party trick. Indeed joint laxity or double-jointedness, as it is also (rightly or wrongly) called, seems to be present in an estimated 10-20% of people, mostly without causing any problems. But that is not to say that such suppleness is not without cost in some cases, where joint hypermobility can be linked with pain and other symptoms in some cases to form joint hypermobility syndrome (JHS). Diagnosing JHS is a relatively straight-forward process given the availability of information such as the Brighton criteria although there is still some discussion on the recognition and acceptance of JHS.

Although perhaps an unusual relationship, it has long been known that patients with JHS also present with a variety of other symptoms not necessarily connected to musculoskeletal symptoms. This paper highlighted a range of symptoms stretching (pardon the wordplay) from cardio-respiratory to gastrointestinal (GI) to other effects like migraine and sleep disturbances. My eye was immediately drawn to the GI issues suggested to be associated with JHS primarily because JHS is a disorder of connective tissue. Under such a broad heading, some (like this paper) have suggested a possible link between JHS and functional bowel problems of unexplained origin. Moving further into the GI-JHS link, a recent paper also asked a few questions about screening for coeliac (celiac) disease in cases of JHS (linked also to Ehlers-Danlos syndrome).

For quite a few years now, there have been rumblings about a possible connection between joint hypermobility and some cases of autism; that is children and adults with autism who seem to be very, very supple. Without trying to make any judgments, UK readers might remember a very nimble young chap with autism who did very well on Britain's Got Talent (quite the photo I am sure you will agree).

Searching the published scientific literature all I have been able to find is the odd case study like this one suggestive of an 'association' in individual cases of rare genetic findings. I note however that joint hypermobility has not yet been explored in a more population-wide systematic way for autism spectrum conditions so reports remain anecdotal.

To finish, and keeping the breakdance theme alive, Run DMC reloaded.