Cannabis use as a potential mediator between childhood adversity and first-episode psychosis: results from the EU-GEI case–control study
Giulia Trotta, Victoria Rodríguez, Diego Quattrone, Edoardo Spinazzola, Giada Tripoli, Charlotte Gayer‐Anderson, Tom P. Freeman, Hannah E. Jongsma, Lucia Sideli, Monica Aas, Simona A. Stilo, Caterina La Cascia, Laura Ferraro, Daniele La Barbera, Antonio Lasalvia, Sarah Tosato, Ilaria Tarricone, Giuseppe D’Andrea, Andrea Tortelli, Franck Schürhoff, Andreı̈ Szöke, Baptiste Pignon, Jean‐Paul Selten, Eva Velthorst, Lieuwe de Haan, Pierre‐Michel Llorca, Paulo Rossi Menezes, Cristina Marta Del‐Ben, José Luis Santos, Manuel Arrojo, Julio Bobes, Julio Sanjuán, Miquel Bernardo, Celso Arango, James B. Kirkbride, Peter B. Jones, Alexander Richards, Bart P. F. Rutten, Jim van Os, Isabelle Austin-Zimmerman, Zhikun Li, Craig Morgan, Pak C. Sham, Evangelos Vassos, Chloe C. Y. Wong, Richard P. Bentall, Helen L. Fisher, Robin Murray, Luis Alameda, Marta Di Forti, EU-GEI WP2 Group
Abstract
BACKGROUND: Childhood adversity and cannabis use are considered independent risk factors for psychosis, but whether different patterns of cannabis use may be acting as mediator between adversity and psychotic disorders has not yet been explored. The aim of this study is to examine whether cannabis use mediates the relationship between childhood adversity and psychosis. METHODS: Data were utilised on 881 first-episode psychosis patients and 1231 controls from the European network of national schizophrenia networks studying Gene-Environment Interactions (EU-GEI) study. Detailed history of cannabis use was collected with the Cannabis Experience Questionnaire. The Childhood Experience of Care and Abuse Questionnaire was used to assess exposure to household discord, sexual, physical or emotional abuse and bullying in two periods: early (0-11 years), and late (12-17 years). A path decomposition method was used to analyse whether the association between childhood adversity and psychosis was mediated by (1) lifetime cannabis use, (2) cannabis potency and (3) frequency of use. RESULTS: The association between household discord and psychosis was partially mediated by lifetime use of cannabis (indirect effect coef. 0.078, s.e. 0.022, 17%), its potency (indirect effect coef. 0.059, s.e. 0.018, 14%) and by frequency (indirect effect coef. 0.117, s.e. 0.038, 29%). Similar findings were obtained when analyses were restricted to early exposure to household discord. CONCLUSIONS: Harmful patterns of cannabis use mediated the association between specific childhood adversities, like household discord, with later psychosis. Children exposed to particularly challenging environments in their household could benefit from psychosocial interventions aimed at preventing cannabis misuse.