Autism spectrum disorders (ASD) are a group of biologically based neurodevelopmental disorders characterized by impairments in three major domains:
1. socialization
2. communication
3. behavior
These disorders include
· autistic disorder (classic autism, sometimes called early infantile autism, childhood autism, or Kanner's autism),
· Rett disorder,
· childhood disintegrative disorder,
· pervasive developmental disorder, not otherwise specified (PDD-NOS), and
· Asperger disorder (also known as Asperger syndrome
A recent study by Ecker et al demonstrated how a multiparameter classification approach can be used to characterize the complex and subtle structural pattern of gray matter anatomy implicated in adults with ASD. A set of five morphological parameters including volumetric and geometric features at each spatial location on the cortical surface was used to discriminate between people with ASD and controls using a support vector machine (SVM) analytic approach and to find a spatially distributed pattern of regions with maximal classification weights.
On the basis of these patterns, SVM was able to identify individuals with ASD at a sensitivity and specificity of up to 90% and 80%, respectively. However, the ability of individual cortical features to discriminate between groups was highly variable, and the discriminating patterns of regions varied across parameters.
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| Morphometric feature | Correctly classified (%) | Sensitivity (%) | Specificity (%) | p |
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| Left hemisphere | | | | |
| All parameters | 85 | 90 | 80 | 0* |
| Cortical thickness | 90 | 90 | 90 | 0* |
| Radial curvature | 72.5 | 65 | 80 | <0.001 |
| Average convexity | 70 | 75 | 65 | <0.004 |
| Metric distortion | 80 | 80 | 80 | 0* |
| Pial area | 77.5 | 70 | 85 | 0* |
| Right hemisphere | | | | |
| All parameters | 65 | 60 | 70 | <0.03 |
| Cortical thickness | 60 | 65 | 55 | <0.01 |
| Radial curvature | 52.5 | 50 | 55 | <0.30 |
| Average convexity | 50 | 40 | 60 | <0.40 |
| Metric distortion | 57.5 | 45 | 70 | <0.06 |
| Pial area | 45 | 45 | 45 | <0.60 |
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The classification was specific to ASD rather than neurodevelopmental conditions in general (e.g., attention deficit hyperactivity disorder). These results confirm the hypothesis that the neuroanatomy of autism is truly multidimensional, and affects multiple and most likely independent cortical features. The spatial patterns detected using SVM may help further exploration of the specific genetic and neuropathological underpinnings of ASD, and provide new insights into the most likely multifactorial etiology of the condition.
@The Journal of Neuroscience August 2010
