A new study published this week in the journal Nature suggests there is evidence of autism in the brain well before symptoms start to appear. Typically, the earliest that children are diagnosed with the disorder is at the age of two, although often times it is even later. Scientists may now be able to detect the disorder well before a child's first birthday via a magnetic resonance imaging (MRI) scan. Scientific American reports: Researchers conducted MRI scans on 150 children three times: at six months old, one year and two years. Just over 100 of the children were at high risk because they had an older sibling diagnosed with autism. The faster growth rate of the surface areas of their brains correctly predicted eight times out of 10 which of the high-risk children would go on to be diagnosed with the condition. Enlargement of the brain seemed to correlate with the arrival of symptoms, says Heather Hazlett, a psychologist at the University of North Carolina's Carolina Institute for Developmental Disabilities (CIDD), and the paper's lead author. Still, with only 100 at-risk children, the study is too small to be considered definitive -- nor should doctors rush to use MRIs to diagnose autism, Hazlett says. But if the study results are confirmed in future research, it could offer a new option for screening high-risk children before their symptoms become obvious -- and possibly at a time when treatment will be most effective.