In 2000, a research team from the University of Edinburgh identified a gene known as Disrupted in Schizophrenia One (DISC1).which was found to increase the chance of people developing schizophrenia, clinical depression and bipolar disorder (manic depression). In the team's latest study they have found another similar gene - phosphodiesterase 4B (PDE4B) - which could also increase the risk of mental illness if damaged. The scientists say the extent of the damage influences the type and severity of illness a person has.

However, the researchers also pointed out that environmental factors could also influence the chances of an individual developing mental illness. The researchers concluded: It is now clear that the DISC1 gene plays an important role in the risk of developing schizophrenia or bipolar affective disorder. 'The new genetic link we have made to PDE4B and how that links back to DISC1 sheds much needed light on these debilitating disorders. It also suggests a new way of thinking about developing new medicines. The Scots researchers worked alongside scientists from pharmaceutical company Merck, Sharp & Dohme Limited. Peter Hutson from Merck Sharp & Dohme, said: Mental illness remains a scourge of society. Our insights into the important role that the proteins PDE4B and DISC1 may play in the mis-function of the brain that leads to schizophrenia will lead our thinking in the development of new treatments for this disorder.