Friday, 29 August 2014

Oxytocin and autism: the hype?

Consider some excerpts from two recent papers looking at oxytocin (OXT) - the "love hormone"(!) - and the autism spectrum disorders (ASDs)...
“It’s not the years, honey. It’s the mileage”

"These findings indicate that dysregulated OXT biology is not uniquely associated with ASD social phenotypes as widely theorized, but instead variation in OXT biology contributes to important individual differences in human social functioning, including the severe social impairments which characterize ASD" according to Karen Parker and colleagues [1]. Some media accompanying this paper can be found here.

and

"Participants who received oxytocin showed no benefit following treatment on primary or secondary outcomes" according to the findings reported by Adam Guastella and colleagues [2].

For those who have followed the autism research scene over the years, you'll know that discussions about some connection between the neuropeptide oxytocin and autism have figured quite prominently. Indeed, I've covered OXT and autism before on this blog (see here). Media headlines like the one from the BBC suggesting that the "Love hormone 'helps autistic brain'" have been quite a regular feature, building up OXT to almost Saintly proportions. Unfortunately, as has often been the case with autism (sorry, the autisms) the science has not exactly followed the hype. Take for example the paper by Dadds and colleagues [3] who, prior to Guastella et al, reported that: "Compared to placebo, intranasal oxytocin did not significantly improve emotion recognition, social interaction skills, or general behavioral adjustment in male youths with autism spectrum disorders".

I'm not saying that all the research on OXT and autism is bunk because that's obviously not true [4]. As per the meta-analysis by Preti and colleagues [5] there may, for example, be some merit in continuing looking at where and when OXT use might be indicated including that related to important comorbidity [6]. The route of administration - intranasal (via the nose) - is for me, also a really interesting drug delivery method which may be applicable to many, many different medicines indicated for autism or peripheral symptoms/conditions.

But what the Parker and Guastella studies do tell us, is that once again, grand over-arching theories of autism seemingly serve no-one well. The study by Bedford and colleagues [7] perhaps said it best with their data arguing: "against cognitive theories of ASD which propose that a single underlying factor has cascading effects across early development leading to an ASD outcome". Replace cognitive theories with biological ones and science seems to be getting a little closer to what looks like the real nature of the autisms, heterogeneity, comorbidity and all... Oh, and then there is some interesting data on how oxytocin might be affecting the "second brain" (gastrointestinal function) as well as the grey-pinkish matter [8]. Move over melatonin (see here)?

Music to close and I'm happy to be stuck with you... (stick with the video, the music does eventually kick in).

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[1] Parker KJ. et al. Plasma oxytocin concentrations and OXTR polymorphisms predict social impairments in children with and without autism spectrum disorder. PNAS. 2014. August 4.

[2] Guastella AJ. et al. The effects of a course of intranasal oxytocin on social behaviors in youth diagnosed with autism spectrum disorders: a randomized controlled trial. J Child Psychol Psychiatry. 2014 August 2.

[3] Dadds MR. et al. Nasal oxytocin for social deficits in childhood autism: a randomized controlled trial. J Autism Dev Disord. 2014 Mar;44(3):521-31.

[4] LoParo D. & Waldman ID. The oxytocin receptor gene (OXTR) is associated with autism spectrum disorder: a meta-analysis. Mol Psychiatry. 2014 August 5.

[5] Preti A. et al. Oxytocin and autism: a systematic review of randomized controlled trials. J Child Adolesc Psychopharmacol. 2014 Mar;24(2):54-68.

[6] Hall SS. et al. Effects of intranasal oxytocin on social anxiety in males with fragile X syndrome. Psychoneuroendocrinology. 2012 Apr;37(4):509-18.

[7] Bedford R. et al. Additive effects of social and non-social attention during infancy relate to later autism spectrum disorder. Dev Sci. 2014 Jul;17(4):612-20.

[8] Welch MG. et al. Oxytocin regulates gastrointestinal motility, inflammation, macromolecular permeability, and mucosal maintenance in mice. Am J Physiol Gastrointest Liver Physiol. 2014 Aug 21. pii: ajpgi.00176.2014.

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ResearchBlogging.org Parker, K., Garner, J., Libove, R., Hyde, S., Hornbeak, K., Carson, D., Liao, C., Phillips, J., Hallmayer, J., & Hardan, A. (2014). Plasma oxytocin concentrations and OXTR polymorphisms predict social impairments in children with and without autism spectrum disorder Proceedings of the National Academy of Sciences DOI: 10.1073/pnas.1402236111


ResearchBlogging.org Guastella AJ, Gray KM, Rinehart NJ, Alvares GA, Tonge BJ, Hickie IB, Keating CM, Cacciotti-Saija C, & Einfeld SL (2014). The effects of a course of intranasal oxytocin on social behaviors in youth diagnosed with autism spectrum disorders: a randomized controlled trial. Journal of child psychology and psychiatry, and allied disciplines PMID: 25087908