I saw on my local news last night a brief story about a new study using magnetic resonance imaging (MRI) to look at the brains of individuals with autism. The idea was to identify regions of the brain that may behave differently in those with autism as compared to those without autism, with the ultimate aim being to provide an objective means of diagnosing the disorder.
Currently, autism is diagnosed using questionnaires and subjective measures, like the Autism Diagnostic Observation Schedule (ADOS) or the Autism Diagnostic Interview (ADI). These tools rely on questions asked of the parents, as well as a clinician's observations of the child's behavior. The subjective nature of the ADOS and ADI open the diagnosis up to some variability, depending on the biases of the clinician and others involved. The result is that there can be slight differences in the diagnostic scores between observers.
This new study may change that.
Published online ahead of print yesterday in the journal Autism Research and titled Atypical diffusion tensor hemispheric asymmetry in autism, Dr. Nicholas Lange, of Harvard Medical School and McLean Hospital, and his colleagues studied 30 males aged 7-28 years and 30 matched controls. They also performed a replication sample with 12 autistic males and 7 matched controls. Individuals with autism were high-functioning and satisfied the full criteria for idiopathic autism (i.e., autism with no clear cause).
The researchers used MRI to look at the white matter microstructure (WMM) of two regions of the temporal lobe: the superior temporal gyrus (STG) and the temporal stem. According to the authors, these regions contain "circuitry central to language, emotion, and social cognition" and would thus be promising candidates for understanding the neurobiology of autism. There seems to be some precedence for this, as the STG has been associated with early onset schizophrenia.
What Lange, et al., found was that these regions exhibited reversed asymmetry of activity compared to controls. In other words, from what I understand, they found that autistic individuals showed greater activity in the right hemisphere and decreased activity in the left hemisphere, while controls had the opposite. Someone a bit more versed in the jargon, please correct me on this if I am wrong (not being a neurologist or radiologist).
The promise this study's findings hold is an objective method of diagnosing autism. With an objective measure such as this, it may be possible to provide a definitive diagnosis earlier than the ADOS or ADI allow, thus providing parents the opportunity to start intervention (e.g., ABA) much sooner. The common idea is that the sooner one can start treatment, the better the outcome will be for the child.
In statements to the press, the researchers stress that their results are not ready for clinical application, and I agree. Although I do not have access to the full text of the study and some of the jargon is a bit above my head, I do realize that this is a small study and its results need to be independently replicated. A couple things come to mind that need to happen. First, they need a larger trial. There are just too few subjects in this one to obtain adequate power to ensure the results are real. Second, they need to use younger subjects. Because children are rapidly changing as they grow, the findings from this study may not hold up in a younger population, rendering the technique useless as a means of early diagnosis. Third, the subjects in this trial were described as high-functioning. Because of the subject selection, the results may not apply for individuals with more severe autism.
There is still a great deal that we do not know about autism, but studies such as this aim to shine a light on that vast unknown. Gradually, we uncover more and more about the physiology and etiology of autism. As the discoveries mount, we come that much closer to finding the cause(s) and, from there, treatments for autism spectrum disorders. Lange, et al., present an interesting study, but it is not a silver bullet. Much, much more work needs to be done before their findings can be applied in the field.