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.

6 comments:

jonathan said...

Hi Michelle, I am still waiting for Morton Gernsbacher or anyone else to give an explaination as to what brain areas would be responsible for autistics inability to talk or speech delays before the age of 36 months, or does she speak about this in the article. Maybe if i get a chance I will go to UCLA biomed and check it out. Until they speak about what exact areas of the brain are involved I really won't buy that this or any other publications represents a significant breakthrough.

I asked Eric Courchesne if it were possible that autistics had some sort of deficit in broca's area in the frontal lobe similar to adult aphasiacs and if this were a good place to look. He stated that developmental brain anomalies were different than those in adults, so it was unlikely they had a problem analogous to broca's aphasia.

Michelle Dawson said...

In response to Mr Mitchell, I suggest he read the paper (Gernsbacher et al., 2008). The methodology and relevant data are there, for anyone who's interested.

Models of autism premised on autistic brains being damaged versions of nonautistic brains have not yet worked out well. Some examples include Jill Boucher's amnesia model, Laurent Mottron's agnosia model (this failure is noted in Mottron et al., 2006), as well as Jocelyne Bachevalier's and David Amaral's amygdala damage models.

For some interesting writing about psychology vs neuroscience, see this and this. From the 2nd link:

"Psychology is needed because we can learn useful, important things about human nature without knowing a thing about what goes on in the brain. A purely psychological understanding of how the visual system processes color, for example, led to the development of color photography and television--well before an MRI showed us which areas of the brain were active while watching TV."

Dinah said...

nice round-up, thank you Michelle, i shall direct my students to these

Anonymous said...

I think not letting infants get third stage Non-REM sleep and fourth stage Non-REM sleep caused the autism epidemics. Parents have been preventing many infants from getting Stage 3 and Stage 4 NREM sleep since the early 1990's. In 1992, only 10% of kids were getting their Stage 3/4 NREM sleep prevented. In 1994 it increase to about 30% and by 1998 it increased to about 65%. Now, over 75% of infants have their Stage 3/4 NREM sleep prevented. I know correlation doesn't always equal causality. But, since stage 3/4 NREM sleep is the only time when memories are transferred from the Hippocampus to the Neocortex I think it could explain part of the rise in autism. All the Best!

Michelle Dawson said...

In response to Anonymous' comment and/or spam (hard to tell, in this era of autism advocacy)... A few years ago, some researchers wrote:

"Epidemics solicit causes; false epidemics solicit false causes."

The same researchers also mentioned evidence for the existence of a

"range of suspected causes of the mythical autism epidemic."

And look, there's another one! Right here, in the comments on a blog post encompassing research showing (again) a high, stable rate of autism. Amazing.

By the way (not that accurate information changes anything), the highest prevalence of autism reported so far has been within a cohort of children born in 1990-1991 (Baird et al., 2006). Children born from 1995 to 1998 have been reported to have a much lower prevalence of autism (Chakrabarti & Fombonne, 2005).

KeithABA said...

"Antipsychotic drugs should no longer be regarded as an acceptable routine treatment for aggressive challenging behaviour in people with intellectual disability."

Hey, Finally something we can completely agree upon!!!!