Tuesday, 4 June 2013

Toe walking and autism

Whilst grazing, as one does, on the plains of the Internet savanna, I stumbled across an interesting article by Williams and colleagues* (open-access) describing a protocol for a study looking at toe walking. As what normally happens with me, memories of autism research times gone by started to flood back, culminating with the question: what ever happened to research looking at toe walking in cases of autism?
En Pointe @ Wikipedia  

Going back quite a few years now, I remembered one occasion when I had research reasons to be in contact with the family of a young girl diagnosed with autism. I quite vividly remember this youngster because of her almost ballet-like gait, hoisting her body weight (which it has to be said was only a very slender frame) on the front portion of her feet; her heels almost never touching the ground for the duration of my visit. The parents I recall, described how she would spend literally hours toe walking; her gait intertwined with various stereotypies depending on her mood and disposition at the time.

Most people will know about the links suggested between autism and issues with gait as per studies like the one from Fournier and colleagues** and the one from Green and colleagues***. Indeed just flicking through an old copy of the ADI (Autism Diagnostic Interview) which I have to hand, I note that in the general behaviours section there is an entry under gait and the words 'up on toes' and 'toe-walking' detailed as part and parcel of the schedule, even if not part of the diagnostic algorithm.

So what evidence is there for toe walking being linked to cases of autism?

  • I was actually quite taken aback as to how few references there were for toe walking research in relation to autism as listed in PubMed. One the more important studies seems to be this one from Barrow and colleagues**** which was also discussed on a SFARI entry (see here). Barrow et al suggested that toe walking might be a facet of quite a few cases of autism - during childhood - and raised "the possibility of a secondary orthopedic deformity" to be present. Barrow also reported a disparity in results between the autisms (autism vs. Asperger syndrome) which might also tie into the various research looking at toe walking from a language point of view (see here) or the possibility of a cognitive developmental issue (see here).
  • The possibility that toe walking might be a 'red flag' for the presentation of autism had been previously discussed as exemplified by the paper from Mandell and colleagues***** (open-access). As a parcel of behavioural presentations including 'hand flapping' and 'sustained odd play', they suggested that toe walking was associated with a decrease in the age of diagnosis. Someone it seems, has been taking its presence quite seriously.
  • The paper by McDougle and colleagues****** (who is talking about some very interesting concepts these days) on tryptophan depletion in cases of autism offers some interesting links between everyone's favourite aromatic amino acid and behaviours such as toe walking. Their results, based on the very complicated area of tryptophan and serotonin chemistry in relation to autism, might have some connection back to more recent mouse model results (see here).

Of course there are other papers looking at toe walking and autism (even with a potential mitochondrial slant to them) but I'm not going to bore you with all the details. Obviously one has to keep in mind that toe walking is not an exclusively autism-linked trait and that some children can present with such a behaviour without presenting with other features linked to a diagnosis of autism or anything else.

I do wonder about a few things based on this collected work: whether we should, following Barrow's suggestion, be screening for orthopaedic issues where sustained toe walking presents in cases of autism, and indeed whether this heralds any link (or not) to things like joint hypermobility (see this post). Whether also toe walking might correlate with other signs and symptoms around either comorbidity (such as cerebral palsy) or even other slightly less well-defined motor-related behaviours are important questions too. That also, for the most part, examination of toe walking in cases of autism has tended to concentrate on the early years of childhood, leaves quite a wide gap into how far maturity acts on such behaviours, and indeed the extent to which toe walking persists into adulthood in cases of autism.

To close, I don't do advice on this blog. But if you really want some life advice, then how about listening to this chap and starting with wearing sunscreen.... (dancing is also a good idea).

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* Williams CM. et al. Do external stimuli impact the gait of children with idiopathic toe walking? A study protocol for a within-subject randomised control trial. BMJ Open. 2013; 3: e002389.

** Fournier KA. et al. Motor coordination in autism spectrum disorders: a synthesis and meta-analysis. J Autism Dev Disord. 2010; 40: 1227-1240.

*** Green D. et al. The severity and nature of motor impairment in Asperger's syndrome: a comparison with specific developmental disorder of motor function. J Child Psychol Psychiatry. 2002; 43: 655-668.

**** Barrow WJ. et al. Persistent toe walking in autism. J Child Neurol. 2011; 26: 619-621.

***** Mandell DS. et al. Factors associated with age of diagnosis among children with autism spectrum disorders. Pediatrics. 2005; 116: 1480–1486.

****** McDougle CJ. et al. Effects of tryptophan depletion in drug-free adults with autistic disorder. Arch Gen Psychiatry. 1996; 53: 993-1000.

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ResearchBlogging.org Barrow WJ, Jaworski M, & Accardo PJ (2011). Persistent toe walking in autism. Journal of child neurology, 26 (5), 619-21 PMID: 21285033