Monday, December 29, 2008

An assortment of 2008 autism papers

Here's a handful of interesting autism-related papers published in 2008, ranging across scales and subjects:

1. Autism and speech: Gernsbacher et al. (2008)

Why can't some autistic children speak? The remarkably few existing explanations for this high-profile phenomenon have collapsed under scrutiny. This embarrassing failure on the part of autism researchers was, at long last, addressed in 2008. Dr Gernsbacher and colleagues found "prominent associations among early oral- and manual-motor skills and later speech fluency" in a large sample of autistic children, who ranged from highly to minimally fluent. Early oral-motor skills are therefore crucial in explaining why some autistic children can't speak. What's more, associated manual-motor skills should be considered a confound in "assessing autistic cognition, receptive language, and ‘nonverbal’ social communication."

2. An effective intervention: Tyrer et al. (2008)

This was a multi-site RCT of three different interventions targeting "aggressive challenging behaviour" in intellectually disabled adults, a minority of whom were autistic. The authors found that haloperidol, risperidone, and placebo all resulted in rapid, dramatic and sustained decrease in the targeted behaviours. And while "no important differences between the treatments were recorded," after four weeks of treatment, "the greatest decrease was with placebo." The conclusion? "Antipsychotic drugs should no longer be regarded as an acceptable routine treatment for aggressive challenging behaviour in people with intellectual disability."

3. Absolute pitch for speech: Heaton et al. (2008)

In the past two years, Pamela Heaton and her colleagues have published a series of papers about enhanced perception of speech in autism. This case study goes a step farther in showing exceptional absolute pitch for speech in an autistic adult, AC, who has had little musical training. The authors found that "AC's naming of speech pitch was highly superior" compared with nonautistic controls who had absolute pitch--many of whom had extensive musical training. While delayed in his development of speech, AC had gone on to be competent in numerous languages. This calls into question the ubiquitous assumption that enhanced processing of perceptual aspects of speech in autistics can only be detrimental to what are regarded as much more important language abilities.

4. Unsung autism epidemiology: Williams et al. (2008)

Autism epidemiology tends to get a lot of media coverage, but this UK study, whose methodology resembles the much-publicized 2007 CDC epi studies, somehow got overlooked. Within "a large representative population sample" the authors found a prevalence of autism ranging from 51.5/10,000 (using more stringent standards) to 61.9/10,000 (using more relaxed standards). That's 1 in 194 to 1 in 162, strikingly lower than the 1 in 86 reported in a famous 2006 UK study involving a slightly older cohort. Within this sample, less than 15% were assessed to be in the range of intellectual disability, with this proportion falling to 13% for those with the specific diagnosis of autism (a higher rate, 27%, was found in those diagnosed with "atypical autism"). Also, having an autistic child was not associated with paternal age (a hot subject these days), and was only slightly associated with maternal age. Clearly, these are not the kinds of findings that attract the media, or autism advocates who produce press releases.

5. Rational autistics, irrational researchers: De Martino et al. (2008)

This paper gets both honourable and dishonourable mention. The study itself was a great idea, well-executed with important and fascinating findings. Autistics were shown to perform with enhanced logical consistency, avoiding irrational and irrelevant biases that distorted decision-making in their nonautistic controls. However, autistics' enhanced performance in this study was interpreted by the authors as a litany of autistic failures, imbalances, impairments, deficits, reduced capacities, weaknesses, and impoverishments (several invocations of some of these), none of which were actually found. The authors concluded that they have discovered a "core neurobiological deficit" in autistics. In years to come, we can look forward to interventions designed to overcome this core autistic deficit and to ensure that autistics become as irrational as nonautistics.


References:

De Martino, B., Harrison, N.A., Knafo, S., Bird, G., & Dolan, R.J. (2008). Explaining enhanced logical consistency during decision making in autism. Journal of Neuroscience, 28, 10746-10750.

Gernsbacher, M.A., Sauer, E.A., Geye, H.M., Schweigert, E.K., & Goldsmith, H.H. (2008). Infant and toddler oral- and manual-motor skills predict later speech fluency in autism. Journal of Child Psychology and Psychiatry, 49, 43-50.

Heaton, P., Davis, R.E., & Happé, F.G. (2008). Research note: Exceptional absolute pitch perception for spoken words in an able adult with autism. Neuropsychologia, 46, 2095-2098.

Tyrer, P., Oliver-Africano, P.C., Ahmed, Z., Bouras, N., Cooray, S., Deb, S., Murphy, D., Hare, M., Meade, M,, Reece, B., Kramo, K., Bhaumik, S., Harley, D., Regan, A., Thomas, D., Rao, B., North, B., Eliahoo, J., Karatela, S., Soni, A., & Crawford, M. (2008). Risperidone, haloperidol, and placebo in the treatment of aggressive challenging behaviour in patients with intellectual disability: A randomised controlled trial. Lancet, 371, 57-63.

Williams, E., Thomas, K., Sidebotham, H., & Emond, A. (2008). Prevalence and characteristics of autistic spectrum disorders in the ALSPAC cohort. Developmental Medicine and Child Neurology, 50, 672-677.