20 augustus 2010

Help, my MRI test says we are autistic

A new technique developed at King’s College London uses a fifteen minute MRI scan to diagnose autism spectrum disorder (ASD). The scan is used to analyze the structure of grey matter in the brain, and tests have shown that it can identify individuals already diagnosed with autism with 90% accuracy. The research could change the way that autism is diagnosed – including screening children for the disorder at a young age.

Currently, ASD is diagnosed behaviorally. There is a list of potential symptoms for autism in the DSM, and anyone exhibiting a certain number of these symptoms can be diagnosed. It’s up to parents or family members to recognize signs of ASD, and to have the child observed by a doctor – only then are they diagnosed. If MRI scans can be shown to rapidly and reliably identify the disorder, it will radically change our diagnostic criteria from behavioral to anatomical.

Researchers at the Institute of Psychiatry (IoP) used MRI scans to evaluate the structure, thickness, and shape of the cerebral cortex (i.e. the outer layer) in subjects’ brains. The study looked at three different groups of males: 20 subjects were healthy controls, 20 had prior diagnoses of ASD, and 19 were diagnosed with ADHD. Each group underwent traditional diagnostic methods first: they were given an IQ test, a psychiatric interview, a physical exam and a blood test. Then the subjects were scanned to see if there were biological correlates to their diagnoses.

The researchers found that ASD patients had special cortical features that allowed their brains to be distinguished from the other two groups. By contrast, ADHD brains could not be distinguished from their healthy counterparts. Because of the small sample size, researchers were unable to distinguish between distinct diagnoses along the autism spectrum (e.g autism vs. Asperger’s). Future research will be needed to determine whether the new technique can tease out diagnostic subcategories of the disorder – and whether the same technique can find these differences in childrens’ brains.

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