Doctors believe the test could be useful

A team from Albert Einstein College of Medicine in New York found brain abnormalities in children with the condition.

They believe these changes disrupt the transmission of signals that regulate behaviour.

The research was presented at a meeting of the Radiological Society of North America.

Our goal is to detect and treat this disease early, so we can stop the progression before full-fledged symptoms develop. Dr Manzar Ashtari

The researchers used a sophisticated scanning technique called diffusion tensor imaging (DTI).

They found abnormalities in tissue known as white matter in an area of the brain called the frontal lobe, which controls emotions and many thinking processes.

In particular, they found problems with the development of a protective coating around brain cells called myelin.

Not only does myelin protect the cells, it also enhances their ability to transmit signals.

But it seems that in patients with schizophrenia, the cells that carry out the process of myelination are defective.

Crucial period

This can render teenagers particularly vulnerable, as myelin is usually laid down most rapidly during the teenage years.

Lead researcher Dr Manzar Ashtari said: "This is a critical time for adolescents who are still maturing emotionally.

"During the myelination process, microstructural damage to developing white matter fibre tracts may lead to developmental abnormalities.

"These are the types of abnormalities we observed in the frontal white matter regions in the children with schizophrenia."

Schizophrenia is usually only diagnosed in young people after symptoms such as hallucinations, delusions, lack of motivation and bizarre behaviour become apparent, and persist for a significant period of time.

In many cases a diagnosis is not made until the patient has become an adult.

However, the researchers hope it should be possible to use DTI to identify white matter abnormalities before symptoms become apparent.

Dr Ashtari said: "Our goal is to detect and treat this disease early, so we can stop the progression before full-fledged symptoms develop.

"If the malformation in the myelination process is the cause of schizophrenia, future special efforts can be focused in production of therapeutic agents that speed up or restart the myelination process."

Complex disease

Paul Corry, of the schizophrenia charity Rethink, told BBC News Online: "In Britain, the average time from first onset of schizophrenia to treatment is 18 months - a totally unacceptable period during which a great deal of lasting damage can be done.

"Reaching people early is essential. These findings highlight some of the possibilities that would come with increased research into schizophrenia. However, schizophrenia is about a lot more than 'faulty wiring.'

"We have a developing understanding of how many people may be at increased risk of developing schizophrenia but do not do so for a host of social and environmental reasons.

"We need to set this research in that social context."