Brain waves could provide the first objective test for schizophrenia, a study here has shown. Measuring the magnetic field produced by electrical currents in the brain can identify patients with the mental disorder, scientists found. Currently, schizophrenia can only be diagnosed by assessing a patient\'s symptoms and looking at their medical history. The findings are published in the journal Physiological Measurement. The psychotic illness usually starts in late adolescence and can cause hallucinations, delusions, paranoia and social withdrawal. Doctors diagnose schizophrenia by ticking off a defined set of symptoms, but during lucid moments patients can appear quite normal, and might even try to cover up their condition. The non-invasive magnetoencephalogram (MEG) technique was used by British and Spanish researchers to compare individuals with schizophrenia and healthy individuals. They found two specific signals that were significantly different in the psychotic patients. In addition, four brain wave signals from the schizophrenia patients were found to change with age in a way not seen in healthy volunteers. Lead researcher Dr Javier Escudero, from the University of Plymouth, south west England, said \"At present, there is no blood, cerebrospinal fluid, brain imaging or neurophysiological test for schizophrenia in routine clinical practice. The diagnosis relies on the interpretation of symptoms and clinical history according to consensus criteria.