IN A world first that could bring hope to thousands of schizophrenics, Melbourne scientists have discovered that a form of the disease is linked to a lack of certain proteins in the brain's lining.

The discovery that one in four schizophrenics has the defect could lead to better treatments and earlier diagnosis of the condition.

The breakthrough, by scientists from the Mental Research Health Institute in Parkville, is being compared to the discovery that type 1 and type 2 diabetes were separate diseases requiring different treatments.

"The same will now be true for schizophrenia, a syndrome that affects one in 100 people," said Professor Brian Dean, head of a 10-member team that has spent 15 years searching for the cause of the illness.

"Now we can study a form of schizophrenia in isolation, it makes it much easier to see what is changed in the brains of subjects.