Scientists have discovered a new method for the early diagnosis of the mental disorder schizophrenia.
The joint study involving Cambridge University found that patients with the condition have high levels of glucose in their brain and spinal fluid.
At present, the diagnosis of the mental disorder is based on interviews and observation and a patient must show symptoms for at least six months.
It is hoped the new method of diagnosis will lead to new and earlier treatment.
The joint study was also conducted by the University of Cologne and Imperial College London.
The team analysed cerebrospinal fluid from 152 volunteers.
Of these, 54 had recently been diagnosed with schizophrenia, 70 were healthy, and 28 were receiving some form of treatment.
Scientists found changes in the way the body metabolised glucose in the group of 54 volunteers, when compared to the group without schizophrenia.
Cambridge University's Dr Sabine Bahn said: "These biomarkers could enable us to develop new early or pre-symptomatic treatments to improve outcomes or even prevent disease symptoms."
Dr Tsz Tsang, from Imperial College London, said: "We were surprised to find such apparent chemical imbalances in the spinal fluids of people with a psychiatric disorder.
"Determining the presence of these 'biomarkers' in fluids that are more easily accessible, such as blood or urine, may provide a more convenient platform for diagnosing neuropsychiatric conditions in the future."
Dr Tsang's colleague, Dr Elaine Holmes, added: "This research could be of huge importance in how we deal with schizophrenia. It shows we can now spot the changes which occur before it becomes a major problem."
Schizophrenia affects about one in every 100 people.
Rethink's Director of Public Affairs, Paul Corry:
Paul Corry, of the mental health charity Rethink, said: "What this research shows is that schizophrenia is a very complex condition involving the interplay of several factors; including biomarkers.
"However, it is important to understand that schizophrenia is much more than the presentation of increased levels of glucose.
"It is profoundly affected by social factors such as poverty, early life experiences and trauma."