Proneness, urbanicity, trauma, and cannabis triggering psychotic states in large urban centers

The two past decades have seen the production of a vast amount of evidence about the genetic and nongenetic factors that contribute to the onset of psychosis from various fields of research. The present article reviews recent evidence from four of these fields that were shown to be strongly associated with psychosis: proneness, urbanicity, trauma, and cannabis use.

The evidence reviewed shows that all four sets of factors investigated here are implicated in the occurrence of psychosis. The specificity and complexity of these associations, however, are not yet clear and recent findings show that the directions of the associations described may be different than we first thought.

It is clear that psychosis is strongly affected by a number of environmental determinants that act in concert with genetic determinants to cause psychotic disorders; however, these influences are complex and their actual impact may be difficult to establish because of poor definitions and specificity. Urbanicity in special is a poorly defined concept that seems to encompass different sets of factors in each study, which hinders discussions and conclusions regarding its impact.