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The association between reasons for first using cannabis, later pattern of use, and risk of first-episode psychosis: the EU-GEI case-control study

Spinazzola, Edoardo, Quattrone, Diego, Rodriguez, Victoria, Trotta, Giulia, Alameda, Luis, Tripoli, Giada, Gayer-Anderson, Charlotte, Freeman, Tom P., Johnson, Emma C., Jongsma, Hannah E., Stilo, Simona, La Cascia, Caterina, Ferraro, Laura, La Barbera, Daniele, Lasalvia, Antonio, Tosato, Sarah, Tarricone, Ilaria, D'Andrea, Giuseppe, Galatolo, Michela, Tortelli, Andrea, Tagliabue, Ilaria, Turco, Marco, Pompili, Maurizio, Selten, Jean-Paul, de Haan, Lieuwe, Rossi Menezes, Paulo, Del Ben, Cristina M., Santos, Jose Luis, Arrojo, Manuel, Bobes, Julio, Sanjuán, Julio, Bernardo, Miguel, Arango, Celso, Kirkbride, James B., Jones, Peter B., O'Donovan, Michael ORCID:, Rutten, Bart P., Van Os, Jim, Morgan, Craig, Sham, Pak C., Austin-Zimmerman, Isabelle, Li, Zhikun, Vassos, Evangelos, Murray, Robin M. and Di Forti, Marta 2023. The association between reasons for first using cannabis, later pattern of use, and risk of first-episode psychosis: the EU-GEI case-control study. Psychological Medicine 53 (15) , pp. 7418-7427. 10.1017/S0033291723001071

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Background While cannabis use is a well-established risk factor for psychosis, little is known about any association between reasons for first using cannabis (RFUC) and later patterns of use and risk of psychosis. Methods We used data from 11 sites of the multicentre European Gene-Environment Interaction (EU-GEI) case–control study. 558 first-episode psychosis patients (FEPp) and 567 population controls who had used cannabis and reported their RFUC. We ran logistic regressions to examine whether RFUC were associated with first-episode psychosis (FEP) case–control status. Path analysis then examined the relationship between RFUC, subsequent patterns of cannabis use, and case–control status. Results Controls (86.1%) and FEPp (75.63%) were most likely to report ‘because of friends’ as their most common RFUC. However, 20.1% of FEPp compared to 5.8% of controls reported: ‘to feel better’ as their RFUC (χ2 = 50.97; p < 0.001). RFUC ‘to feel better’ was associated with being a FEPp (OR 1.74; 95% CI 1.03–2.95) while RFUC ‘with friends’ was associated with being a control (OR 0.56; 95% CI 0.37–0.83). The path model indicated an association between RFUC ‘to feel better’ with heavy cannabis use and with FEPp-control status. Conclusions Both FEPp and controls usually started using cannabis with their friends, but more patients than controls had begun to use ‘to feel better’. People who reported their reason for first using cannabis to ‘feel better’ were more likely to progress to heavy use and develop a psychotic disorder than those reporting ‘because of friends’.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Medicine
MRC Centre for Neuropsychiatric Genetics and Genomics (CNGG)
Publisher: Cambridge University Press
ISSN: 0033-2917
Date of First Compliant Deposit: 5 June 2023
Date of Acceptance: 3 April 2023
Last Modified: 16 Jan 2024 13:47

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