Cannabis and psychosis: What can daily diaries tell us about who is vulnerable?

The association between cannabis use and the initial development of psychotic symptoms has attracted increased interest over the past decade. In particular, researchers have attempted to elucidate whether cannabis use increases the risk of psychosis among vulnerable individuals or may just represent attempts to self-medicate distressing symptoms. While a growing literature suggests that cannabis use may contribute to the development of psychotic symptoms, these findings are based primarily on retrospective assessments that have limited ability to clarify the temporal link between cannabis use and psychotic symptoms. The authors review the literature regarding the link between cannabis use and psychotic symptoms; point out the limitations associated with retrospective assessments; and discuss advantages of incorporating daily diary methods, such as Experience Sampling Method (ESM), to study cannabis use and symptoms during daily functioning in "real world" environments. The authors also discuss potential future applications of ESM in research and clinical practice that may inform the identification of individuals vulnerable to develop psychotic symptoms, as well as the development of treatments that target this population.