The way autism is diagnosed could become less subjective by using a brain-imaging-based test that is being developed by researchers and that, in early trials, was 94 percent accurate. Autism is now diagnosed through a symptom-based test: A health-care provider observes a patient for the characteristics outlined in the psychology reference book, "The Diagnostic and Statistical Manual IV."

The new test is based on a magnetic resonance imaging (MRI) screen. In its trials, it was able to distinguish between people who have autism and others by changes in their brains. However, the findings were preliminary - researchers tried out this method of diagnosis on only two groups of patients; both groups were males with high-functioning autism.

But this test brings "the potential for younger people to have their autism diagnosed" earlier, said study researcher Nicholas Lange, associate professor of psychiatry at Harvard Medical School and director of the Neurostatistics Laboratory at McLean Hospital in Massachusetts.

Experts say the earlier that autism is diagnosed, the better the intervention by health care experts. Right now, autism can be diagnosed in patients as young as age 3. The disorder involves having trouble communicating and interacting with others, and behaving inappropriately in social situations.

Previous work has suggested MRIs could be used to diagnose autism. A study published in October in the journal Cerebral Cortex found that changes in oxygen levels in the brains of people with autism were less synchronized than in the brains of people without the disorder, meaning areas of the patients' brains weren't signaling properly. These oxygen changes can also be seen in an MRI of the brain, according to University of Utah researchers.

Who has it, and who doesn't?

In Lange's study, 30 men ages 8 to 26 who had been subjectively diagnosed with high-functioning autism, underwent MRI scans of their brains, as did 30 men without autism. The researchers also conducted an imaging test that let them observe how water flows throughout the brain.

They examined six parts of the brain's circuitry and found one observable difference in the men who had autism. In a typical, healthy person, water flows in an organized manner in the left side of the brain and flows in a disorganized way in the right side of the brain.

But in the men with autism, water flowed in a disorganized way in the left side of the brain and in an organized way in the right side of the brain, he said.

"Out of the 30 [men with autism] that we had, we were able to correctly distinguish 28 of them," Lange told MyHealthNewsDaily.

Researchers repeated the study with a second group of 12 men with autism and seven men without autism, and were able to correctly identify all the men who had autism.

"This is very surprising, and it increases the ability to distinguish" people with autism, Lange said.

Future tests needed