At present, diagnoses of schizophrenia are based on observations of patients' behaviour. Typically, they feel their lives are being controlled, and their thoughts directed by others. They hear voices and can form delusions about the world around them. Just 1 per cent of the population suffer from the condition, which is known to involve the activity of dopamine, a chemical involved in communications between nerve cells.
Dopamine locks on to receptor molecules on brain cells and directs their behaviour.
So the Weizmann team analysed the genetic material that controls the making of receptors instead - and found a significant difference in one particular type, known as D3 receptors. It was found schizophrenics had, on average, more than three times the amounts of dopamine of healthy individuals, with levels varying from between 2.4 to 7.1. Pinpointing mental status from blood could be a powerful tool in dealing with psychiatric illnesses. But Fuchs warned the technique would have to be rigorously tested before being brought into widespread use. It is unlikely to be accurate enough.