Children with autism could soon be diagnosed using a 15-minute brain scan developed by British scientists.
Tests on adults show an accuracy rate of 90 per cent, which paves the way for detecting the condition at an earlier stage when treatment may be more effective.
At £200 a time, the scanning technique is much cheaper than conventional diagnosis using a team of clinicians, which can up to £2,000.
Scientists behind the breakthrough at the Institute of Psychiatry, King’s College London, hope it could be in widespread use within two years.
Dr Christine Ecker, who carried out the study funded by the Medical Research Council, said more than 600,000 Britons have autism but half are undiagnosed.
She said: ‘We have shown that a scan is fast and accurate.
‘It could help get rid of long waiting lists, which are extremely stressful for patients and their families, and allow treatment to be offered sooner.’
Autism, or autistic spectrum disorder (ASD), is an umbrella term for a range of developmental disorders that have a lifelong effect on someone’s ability to interact socially and communicate.
Around one child in every 100, mostly male, has autism and the number of cases seems to be increasing.
The new technique uses a magnetic resonance imaging (MRI) scanner and computer software to produce 3D images that can detect changes in the structure of different regions of the brain.
Some parts vary in size when compared with a composite based on healthy brains, particularly in areas dealing with language and behaviour. For instance, changes in the volume of the basal ganglia, which regulates movement, may result in repetitive behaviour.
Tests on 20 healthy adults, 20 adults with ASD and 19 adults with Attention Deficit Hyperactivity Disorder, all men aged between 20 and 68 years, found scanning was 90 per cent accurate, according to a study published in the Journal of Neuroscience.
Dr Ecker said about 10 per cent of the men were either wrongly diagnosed with autism or incorrectly given the all-clear, but this represented a high degree of accuracy for medical testing.
She said tests on children were about to begin, along with more research on adults.
She said: ‘These differences in the brain are more pronounced in children so we are confident it will prove even more accurate.’
Scanning will not replace clinicians making a diagnosis but assist the process, she added.
‘It will speed it up. Unfortunately autism is a lifelong condition and there is no cure yet, but if behavioural intervention is given earlier then it could greatly improve the quality of these people’s lives,’ she added.
At present, ASD is chiefly diagnosed by observing behavioural traits using a battery of tests which can take a whole day and cost as much as £2,000.
Universities and Science Minister David Willetts called the study ‘very exciting’.
Declan Murphy, professor of psychiatry and brain maturation at the Institute of Psychiatry, who led the research, said: ‘We think that our new method will help people with ASD to be diagnosed more quickly and cost-effectively.’