Dual case study of continued use vs cessation of cannabis in psychosis: a theoretically informed approach to a hard problem

Purpose Cannabis use in the context of psychosis has been shown to have a negative impact on prognosis and yet it is difficult to treat. Recent randomized controlled trials all have negative findings and novel approaches is sought after. This paper aims to use an embodied cognition framework to add to the understanding of cannabis use in psychosis. Design/methodology/approach The paper presents longitudinal, qualitative data on two individuals diagnosed with schizophrenia and using cannabis at least twice weekly prior to inclusion in the study. Factors influencing cannabis use were mapped in dialogue with the participants. Each participant was interviewed six times over the course of a year. The analysis was informed theoretically to describe processes maintaining or ameliorating cannabis use over time. Findings This study shows that a systems approach for understanding changes in cannabis use is meaningful; the richness of observations add to the understanding of differences in outcomes. Findings suggest that reductions in cannabis use in psychosis could be dependent on synergistic effects between contextual conditions. Attending closer to the experience of patients may help inform future interventions. However, interventions focusing on single mechanisms may be futile, if an array of individual, formative experiences are a prerequisite for change. A systemic understanding of dual diagnosis calls for tailored, individualized interventions. Originality/value The research tests a novel systemic perspective on cannabis use in psychosis by applying it to qualitative longitudinal data. Adding a systemic perspective may help develop future interventions addressing cannabis use in psychosis, which has long been considered a “hard problem” in dual diagnosis treatment.