December 2, 2010 — A joint research project between Harvard University and University of Utah scientists has resulted in the development of a new biological test for autism.
The test, which uses magnetic resonance imaging (MRI) to measure deviations in brain circuitry, is an objective way of identifying individuals with the disorder and could someday replace the subjective methods that are currently used.
"Autism is diagnosed now with a very subjective measure, a formal interview that takes 4 hours, and with observation of the child for another hour or so. But it’s the doctor’s call. This test is a more definitive way of determining autism early on, by pointing to something in the brain that is biologically based," lead study author Nicholas Lange, ScD, associate professor of psychiatry at Harvard Medical School, Boston, Massachusetts, told Medscape Medical News.
The study was published online November 29 in Autism Research.
Dr. Lange, senior study author Janet E. Lainhart, MD, from the University of Utah, Salt Lake City, and colleagues set out to explore the hypothesis that study of white matter microstructure in regions of the brain responsible for language, emotion, and social cognition would further the understanding of autism neuropathology.
Diffusion tensor imaging measures white matter microstructure by mapping directions of water diffusion in a local brain tissue frame of reference.
"We used this technique because other types of MRI scans, such as the ones that compare the sizes of various parts of the brain between healthy individuals and individuals who have a particular brain disorder, have not shown much difference in autism," Dr. Lange explained.
The researchers took white matter microstructure measurements from the superior temporal gyrus and temporal stem in 30 high-functioning males aged 7 to 28 years who were diagnosed as having autism by the standard subjective scoring system and in 30 matched controls.
They found that, in the subjects with autism, less information was being exchanged in the key areas of the brain responsible for language, social functioning, and emotional behavior.
High Accuracy
"The test was able to detect autism in this high-functioning population with 94% accuracy. This technique shows that someone with autism has less organized wiring," said Dr. Lange.
"So reading the body language of someone you want to get to know is difficult or impossible. Most, if not all people with autism have no friends. There appears to be a lack of ordered directional diffusion along the axons to help them make those connections, and we were able to pinpoint just where this is occurring through this brain circuitry imaging," he added.
Dr. Lange said it is his hope that this test will someday be used in the clinic to make an accurate and prompt diagnosis in young children.
"The diagnosis, if made early enough, would allow the treatment to be tailored to the degree of autism. Intense intervention might help that child, but it is best started early on."
However, the test is not yet ready for prime time.
"We are continuing to study and develop the test, and more findings are due out a year or 2 from now. We are also planning future studies to look at patients with high-severity autism and younger children less than 7 years of age and patients with brain disorders, such as developmental language disorders, attention-deficit/hyperactivity disorder, and obsessive compulsive disorder, who do not have autism."
The study was sponsored by the National Institutes of Mental Health. Dr. Lange and Dr. Lainhart have disclosed no relevant financial relationships.
Autism Res. Published online November 29, 2010.
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Authors and Disclosures
Journalist
Fran Lowry
is a freelance writer for Medscape.
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We sour green apples live our own inscrutable, carefree lives... (Max Frei)
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03 Dec 2010, 4:18 pm
