Tuesday, February 7, 2012

Conference report: BioAutism 2012

BioAutism speakers and organisers. Photo by Dee McGrath (QBI).


A couple of weeks ago, I attended the BioAutism 2012 conference at the (very swanky) Queensland Brain Institute in Brisbane. It was a pretty long day for me but, although I was cursing when my alarm went off at 4:30am, it was well worth the trip.

What struck me as I sat waiting for the plane home, digesting the meeting (and a slightly plasticky pizza), is that there are a whole lot of Australian autism researchers doing a whole lot of really interesting work. If there was a theme to the meeting, it was one of people looking at familiar problems in unfamiliar and innovative ways.

Rather than trying to describe all 13 presentations, I thought I'd share three that really illustrate this point.

Broader Autism Phenotype in extended families

The first example came from a presentation by Natasha Brown, looking at the broader autism phenotype - the idea that relatives of people with autism tend to have some traits characteristic of autism, even if they don't actually meet criteria for autism themselves.

The conventional approach is to just look at a group of people who have an autistic relative and compare them to a group of people who don't. However, as Brown pointed out, it's becoming increasingly apparent that there are a wide range of different genetic events that are implicated in causing autism, so lumping relatives of different autistic people together risks losing or diluting a lot of useful information at both the clinical and the genetic level.

The approach that Brown and colleagues are taking is to identify extended families that include multiple autistic individuals, look at how different autistic traits cluster together, and then look for genetic anomalies that predict whether a person within the family will be autistic or show substantial autistic traits. Brown presented data from one family that included nine individuals with autism and 15 with the broader autism phenotype. By looking at the family tree and comparing this to the results of genetic testing, they were able to tentatively link the presence of autism or autistic traits to a small region on chromosome 17.

Gut malfunction in a mouse model of autism

A second example of a slightly leftfield approach was work presented by Elisa Hill, also of Melbourne Uni. Like other research groups across the world, she and her colleagues have been looking at the behaviour of mice with a mutation of the Neuroligin gene and the effects of different drugs on those behaviours.

But they have also been looking at how the genetic mutations affect the intestines of these mice. It turns out that we (as in us vertebrates) have a complete nervous system in our intestines, known as the enteric nervous system; and that genes expressed in the brain are also expressed in the gut. Hill and colleagues dissected out the colons of some of the mice and measured the colonic muscle contractions in response to different drug solutions.  The muscle contractions were reduced in the mutant mice, suggesting that the mutation affected the way the gut works.

This is pretty interesting because many people with autism have gastro-intestinal problems, leading to the hypothesis that gut problems somehow cause autism. Hill's preliminary findings point towards an alternative explanation for this link - certain mutations that cause autism might also lead to malfunction of the gut.

Individual differences in responsiveness to intervention

Finally, Giacomo Vivanti from Latrobe University presented some preliminary findings from a study looking at the effectiveness of the Early Start Denver Model intervention. Compared to other interventions, this has a relatively good evidence base, with a randomized control trial suggesting that kids with autism on the program tend to do better than those who don't get the intervention.

However, as Vivanti noted, not all kids derive the same benefit. Some show huge improvements, but others are less responsive. So rather than just seeing whether the intervention overall had a net positive effect, the Latrobe researchers are trying to work out whether there are characteristics of individual children that predict the extent to which they are likely to benefit.

The preliminary results were encouraging and somewhat surprising. The best predictor wasn't a measure of language use or social interaction, as I would have expected, but how much the kids interacted appropriately with objects.

On reflection, this perhaps makes sense, if we assume that kids who don't interact with objects are less likely to engage in the activities that are involved in the intervention, and so are less likely to benefit. It's still very early days with this research, but I'm convinced that this strategy is the way to go for intervention research.


Further reading:

1 comments:

  1. Jon;
    The discussion of the broader autism phenotype (BAP) at the conference is intriguing. There is a huge difference between a trait and a disorder. I have been researching the data behind a new conceptual model of autism first introduced by Michael Rutter which states the heritable genetic variances underlying what has been called the broader autism phenotype (BAP) may not be the same as the genetic and environmental factors involved in the disruption of early brain development and the transition to a broad spectrum of neurodevelopmental and neuropsychiatric disorders with or without co-occurring autism. The model implies that there are two independent mechanisms operating in autism etiology that act synergistically, in what Rutter has called the ‘two-hit’ hypothesis. When both independent mechanisms are present it follows a developmental trajectory leading to clinically diagnosed autism. When the BAP component part is not present it leads to a broad spectrum of developmental problems but does not lead to a clinical diagnosis of autism.

    The model can be observed in studying Downs Syndrome with or without co-occurring autism. Plomin’s group in the UK has been studying the prevalence of and heritability of the BAP in general population twins by recruiting thousands of twin pairs present in the Twins Early Development Registry (TEDS). Plomin’s group has found that the genetic variances underlying the BAP is highly heritable and that 5% of all general population children were found to possess ‘extreme autistic-like traits’ and “Around 10% of all children showed only social impairment, only communicative difficulties or only rigid and repetitive interests and behavior, and these problems appeared to be at a level of severity comparable to that found in children with diagnosed ASD in our sample ( Happe Arnold et al )”.

    Independent mechanisms have been demonstrated in Downs Syndrome with or without co-occurring autism. Ghaziuddin compared a group of Downs Syndrome children with or without co-occurring autism. In Downs Syndrome with co-occurring autism there was an excess of first degree relatives who met the description of BAP features compared to first degree relatives in children with Downs Syndrome without co-occurring autism who did not meet the description of BAP features. None of the first degree relatives in Downs Syndrome with co-occurring autism were diagnosed either with Downs Syndrome or autism ( Ghaziuddin M ) (Ghaziuddin1997 ).

    References

    Happe F, Ronald A, Plomin R. Time to give up on a single explanation for autism. Nat Neurosci. 2006 Oct;9(10):1218-20.
    http://dept.wofford.edu/neuroscience/neuroseminar/pdfFall2011/4-explaining-autism.pdf

    Ghaziuddin M. Autism in Down's Syndrome: family history correlates. J Intellect Disabil Res. 1997 Feb;(Pt1):87-91.
    http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2788.1997.tb00681.x/abstract


    Ghaziuddin M. Autism in Down's Syndrome: A family history. J Intellect Disabil Res. 2000 Oct;44(Pt 5):562-6.
    http://www.ncbi.nlm.nih.gov/pubmed/11079353

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