Researchers in the EU are attempting to unravel the causes of schizophrenia and related psychotic disorders by examining the role that genes and different environments play in the onset of these conditions. Epidemiologists, psychologists, psychiatrists, neuroscientists, pharmacologists, biostatisticians, and geneticists will all play a role in this unique large-scale project. EU support for the research came from the EU-GEI ('European network of national schizophrenia networks studying gene-environment interactions') project, which received EUR 11.62 million under the Health Theme of the Seventh Framework Programme (FP7). The project, involving more than 7,500 patients and their families from 15 countries, is the largest effort to date to understand how gene-environment interactions underlie schizophrenia risk. Partners involved in the project include the nationally funded schizophrenia or mental health networks of France, Germany, the Netherlands, Spain, Turkey and the UK, as well as other research institutes and a number of small and medium-sized (SMEs) in Australia, Austria, Belgium, Hong Kong/China, Ireland, Italy and Switzerland. The project is designed to focus on the effects of gene-environment interactions on brain pathways and psychological vulnerability, and to elucidate how subtle, but measurable behavioural expressions of vulnerability for psychotic disorder are mediated by cerebral and psychological pathways. Follow-up research in the project is expected to establish why, in some individuals, expression of vulnerability will never progress to overt illness, while in others, schizophrenia will manifest in clinical expression. Led by Professor Jim van Os from the School for Mental Health and Neuroscience (MHeNS) at the University of Maastricht (MUMC) in the Netherlands, the researchers want to examine behavioural expressions of vulnerability, occasioned by gene-environment interactions, that they say are 'best captured as subtle alterations in mood, perception, volition and thought in response to minor stressors in the flow of daily life'. However, since no tools currently exist to adequately monitor these alterations, European enterprises and start-ups in the EU-GEI project will develop new technology to make such monitoring possible. The scientists believe that given the evidence for detrimental effects of big cities on mental health and a wide range of somatic disorders, the impact of increasing urbanisation and other environmental risk factors in European countries, such as migration, should be prioritised in the research. They highlight that growing up in an urban area has been shown to be associated with an increased risk of developing psychotic disorder in later life; children growing up in big cities seemingly have a more than two-fold risk of developing such a disorder compared to children in rural environments. Migration has likewise been cited as a trigger for psychotic disorders with immigrant populations facing a much higher risk of developing them compared to the risk in both the host country and the country of origin. Other studies have found that cannabis use, in particular heavy use during adolescence, also increases the risk of developing a psychotic disorder, as does childhood trauma. The researchers hope that the development of new tools during this project will allow them not only to actually measure vulnerability to psychotic disorders caused by gene-environment interaction, but also to monitor, and possibly even modify, vulnerability at the behavioural level. The project is due to end in May 2015.