Ben-Gurion University and Carnegie Mellon University researchers have disproved a widespread belief among neuroscientists that the brains of people with autism look different than those who do not have autistic spectrum disorder (ASD). In the largest MRI study to date, the Beersheba and Pittsburgh researchers have shown that the brain anatomy of individuals aged 6 to 35 is mostly indistinguishable from that of typically developing individuals and, therefore, of little clinical or scientific value. The study, “Anatomical Abnormalities in Autism?” was just published in the prestigious Oxford journal Cerebral Cortex. The researchers used data on over 1,000 people in the new the Autism Brain Imaging Data Exchange (ABIDE), which provides an unprecedented opportunity to conduct large-scale comparisons of anatomical MRI scans across autism and control groups. This recently released database is a worldwide collection of MRI scans (half with autism and half controls). “Our findings offer definitive answers regarding several scientific controversies about brain anatomy, which have occupied autism research for the past 10 to 15 years,” said Dr. Ilan Dinstein of BGU's psychology and brain and cognitive sciences departments. “Previous hypotheses suggesting that autism is associated with larger intra-cranial gray matter, white matter and amygdala volumes, or smaller cerebellar, corpus callosum and hippocampus volumes were mostly refuted by this new study,” he said. “In the study we performed very detailed anatomical examinations of the scans, which included dividing each brain into over 180 regions of interest and assessing multiple anatomical measures, such as the volume, surface area and thickness of each region.” The researchers then examined how the autism and control groups differed regarding each region and also with respect to groups of regions using more complex analyses. “The most striking finding here was that anatomical differences within both the control group and the autistic group was immense and greatly overshadowed minute differences between the two groups,” Dinstein stated. “For example, individuals in the control group differ by 80 percent to 90% in their brain volumes, while differences in brain volume across autism and control groups differed by 2% to 3% at most. This led us to the conclusion that anatomical measures of brain volume or surface areas do not offer much information regarding the underlying mechanism or pathology of ASD,” explained Dinstein, whose team included Prof. Marlene Behrmann of Carnegie Mellon's psychology department. “These sobering results suggest that autism is not a disorder associated with specific anatomical pathology, and as a result anatomical measures alone are likely to be of low scientific and clinical significance for identifying children, adolescents and adults with ASD, or for elucidating their neuropathology,” he said. Dinstein said he believed that more complex explanations involving combinations of measures in more homogeneous sub-groups were likely to be the answer. This conclusion stands in sharp contrast to numerous reports of significant anatomical differences described by smaller studies, which have typically included comparisons of small samples of only 40 to 50 individuals.
