A "significant step" has been made towards earlier diagnosis and treatment of schizophrenia, researchers have claimed.
The results of a new study have shown that those who go on to develop schizophrenia suffer from an accelerated shrinking of the brain before they become unwell.
Giving brain scans to young people with a family history of the illness could predict the onset of the disease, researchers said.
The findings, published in the journal Biological Psychiatry, follow a decade of work on the subject by researchers at the University of Edinburgh.
The team examined people at high risk of schizophrenia who had two close relatives with the disorder and were aged between 16 and 25 at the start of the study.
The university said it is the first time that such changes in brain size have been found in people at high risk of schizophrenia before they develop any symptoms.
Unlike previous studies, these changes cannot be due to medication because all of the people in the study were not using medication when they took part.
In healthy people, the brain begins to shrink from early adulthood onwards.
Schizophrenia affects one in every 100 people.
It is known that accelerated shrinking of the brain occurs in people with manic depression and schizophrenia, but before now it was not known whether these changes happened before people became unwell.
The study showed that the loss of brain tissue is concentrated in areas of the brain that control personality, decision-making and social behaviour.
Researchers said scans could be used to pinpoint shrinkage of the brain in people at high risk of schizophrenia and could help doctors diagnose the condition and start treatment at an earlier stage, perhaps before illness first appears.
The team looked at the brain scans of 146 people with a family history of schizophrenia, but who had not yet experienced any symptoms, and compared them to scans of 36 people with no such risk.
The scans were taken every 18 months over a 10-year period.