Regions of the brain are known to differ in people with autism. Red and orange show areas that are thicker or larger, while the blue shows a reduction in size compared with a non-autistic brain. (MRC)

Autism in adults can be diagnosed using MRI brain scans, British scientists have found.

The 15-minute scans were used to identify autism spectrum disorder (ASD) with an accuracy of 90 per cent in 20 people who were previously diagnosed.

"Our study offers a 'proof of concept' for describing the complex multidimensional grey matter differences in ASD," Dr. Christine Ecker, a lecturer in forensic and neurodevelopmental sciences at London's Institute of Psychiatry and her co-authors concluded in Wednesday's issue of the Journal of Neuroscience.

In the experiment, magnetic resonance imaging scans were reconstructed into 3-D images and analyzed using computer software programmed to spot structural changes in the brain's grey matter by measuring areas that relate to behaviour, language and vision. Changes in shape and thickness point to the disorder.

A capability to diagnose ASD based on objective biological tests rather than the current method of relying on personality traits could help identify patients more quickly who need treatment, Ecker said.

The tests were done on 20 men aged 20 to 68 and an equal number of healthy volunteers.

Participants were tested the conventional way and then had their brains scanned to compare the two techniques.

The scans were used to correctly identify ASD 90 per cent of the time, and 80 per cent of the healthy control subjects were correctly classified, the researchers said.

Application for children unclear

The study's authors cautioned that the technique strongly depends on the characteristics of the sample of participants, which in this case were high-functioning adults with autism and Asperger's syndrome.

The MRI scans are currently a research tool and not a diagnostic one.

In children, other studies suggest accelerated brain growth is one of the strongest markers for autism.

"I think there's considerable reason to believe that whatever is distinct about brain development may actually be different in children than it is in adults," said Dr. Lonnie Zwaigenbaum of the Autism Research Centre at the University of Alberta in Edmonton.

Combined with other resources, however, the findings could help diagnose adults with mild autism, Zwaigenbaum said.

Missing piece

Serge Deuvletian, 35, of Montreal was diagnosed with a form of autism in 2008 after being on a waiting list for two years.

"It's pretty much like living your whole life with a piece of the puzzle missing without knowing exactly what the piece is or where the piece is," said Deuvletian. "So it was nice to finally find that piece."

Communication was difficult, Deuvletian recalled. He never dated in high school or college, and said he missed out on some career opportunities.

But Deuvletian added a lot has changed since he was finally diagnosed. He is now a veterinarian with access to services and has made friends with other people who live with the condition.

ASD is a lifelong and disabling condition caused by abnormalities in brain development.

The research was funded by the U.K. Medical Research Council and the Wellcome Trust and National Institute for Health Research.