The contribution of cannabis use to variation in the incidence of psychotic disorder across Europe (EU-GEI): a multicentre case-control study

Crocettarachele Sartorio, Giada Tripoli, Giovanna Marrazzo, Laura Ferraro, Caterina La Cascia, Fabio Seminerio, Daniele La Barbera, Marta Di Forti, Ilaria Tarricone, Mara Parellada, Esther Lorente-Rovira, Anne-Marie Tronche, Doriana Cristofalo, Peter B Jones, Tom P Freeman, Lucia Sideli, Javier González Peñas, Robin M Murray, Simona A Stilo, Elsje Van Der VenThomas Charpeaud, Charlotte Gayer-Anderson, Daniella Van Dam, Gonzalo López Montoya, Craig Morgan, Stephanie Beards, Manuel Arrojo, Grégoire Baudin, Ma Soledad Olmeda, Flora Frijda, Covadonga M Díaz-Caneja, Emilio Sánchez, Kathryn Hubbard, Giada Tripoli, Fabio Seminerio, Baptiste Pignon, Crocettarachele Sartorio, Julio Sanjuán, James B Kirkbride, Pedro Cuadrado, Silvia Amoretti, Harriet Quigley, Paz Garcia-Portilla, Marta Rapado, Giovanna Marrazzo, Estela Jiménez-López, Eva Velthorst, Jim Van Os, Miguel Bernardo, Miquel Bernardo, Mario Matteis, Nathalie Franke, Emiliano González, Hannah E Jongsma, Elles Messchaart, Covadonga Martínez, Covadonga M Díaz-Caneja, Paulo Rossi Menezes, Aziz Ferchiou, Victoria Rodriguez, Jean-Romain Richard, Cristina Marta Del-Ben, Rosana Shuhama, Domenico Berardi, Juan Nacher, Laura Roldán Díaz, Ma Dolores Moltó, Camila Marcelino Loureiro, Sarah Tosato, Michael Lynskey, Pak C Sham, José Juan Rodríguez Solano, Andrea Tortelli, Enrique García Bernardo, Celso Arango, Stéphane Jamain, Bart Pf Rutten, Franck Schürhoff, Fabian Termorshuizen, Chiara Bonetto, Pilar A. Sáiz, Javier Costas, Julio Bobes, Jean-Paul Selten, Michael Lynskey, Marion Leboyer, Paulo Rossi Menezes, Lieuwe De Haan, Mirella Ruggeri, Angel Carracedo, Andrei Szöke, Cathryn M Lewis, Diego Quattrone, Bibiana Cabrera, Lucia Sideli

Risultato della ricerca: Article

58 Citazioni (Scopus)

Abstract

BackgroundCannabis use is associated with increased risk of later psychotic disorder but whether it affects incidence of the disorder remains unclear. We aimed to identify patterns of cannabis use with the strongest effect on odds of psychotic disorder across Europe and explore whether differences in such patterns contribute to variations in the incidence rates of psychotic disorder.MethodsWe included patients aged 18–64 years who presented to psychiatric services in 11 sites across Europe and Brazil with first-episode psychosis and recruited controls representative of the local populations. We applied adjusted logistic regression models to the data to estimate which patterns of cannabis use carried the highest odds for psychotic disorder. Using Europe-wide and national data on the expected concentration of Δ9-tetrahydrocannabinol (THC) in the different types of cannabis available across the sites, we divided the types of cannabis used by participants into two categories: low potency (THC <10%) and high potency (THC ≥10%). Assuming causality, we calculated the population attributable fractions (PAFs) for the patterns of cannabis use associated with the highest odds of psychosis and the correlation between such patterns and the incidence rates for psychotic disorder across the study sites.FindingsBetween May 1, 2010, and April 1, 2015, we obtained data from 901 patients with first-episode psychosis across 11 sites and 1237 population controls from those same sites. Daily cannabis use was associated with increased odds of psychotic disorder compared with never users (adjusted odds ratio [OR] 3·2, 95% CI 2·2–4·1), increasing to nearly five-times increased odds for daily use of high-potency types of cannabis (4·8, 2·5–6·3). The PAFs calculated indicated that if high-potency cannabis were no longer available, 12·2% (95% CI 3·0–16·1) of cases of first-episode psychosis could be prevented across the 11 sites, rising to 30·3% (15·2–40·0) in London and 50·3% (27·4–66·0) in Amsterdam. The adjusted incident rates for psychotic disorder were positively correlated with the prevalence in controls across the 11 sites of use of high-potency cannabis (r = 0·7; p=0·0286) and daily use (r = 0·8; p=0·0109).InterpretationDifferences in frequency of daily cannabis use and in use of high-potency cannabis contributed to the striking variation in the incidence of psychotic disorder across the 11 studied sites. Given the increasing availability of high-potency cannabis, this has important implications for public health.
Lingua originaleEnglish
pagine (da-a)427-436
Numero di pagine10
RivistaTHE LANCET. PSYCHIATRY
Volume6
Stato di pubblicazionePublished - 2019

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Cannabis
Psychotic Disorders
Case-Control Studies
Incidence
Dronabinol
Logistic Models
Population
Population Control
Causality
Brazil
Psychiatry
Public Health
Odds Ratio

All Science Journal Classification (ASJC) codes

  • Psychiatry and Mental health
  • Biological Psychiatry

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The contribution of cannabis use to variation in the incidence of psychotic disorder across Europe (EU-GEI): a multicentre case-control study. / Sartorio, Crocettarachele; Tripoli, Giada; Marrazzo, Giovanna; Ferraro, Laura; La Cascia, Caterina; Seminerio, Fabio; La Barbera, Daniele; Di Forti, Marta; Tarricone, Ilaria; Parellada, Mara; Lorente-Rovira, Esther; Tronche, Anne-Marie; Cristofalo, Doriana; Jones, Peter B; Freeman, Tom P; Sideli, Lucia; González Peñas, Javier; Murray, Robin M; Stilo, Simona A; Van Der Ven, Elsje; Charpeaud, Thomas; Gayer-Anderson, Charlotte; Van Dam, Daniella; López Montoya, Gonzalo; Morgan, Craig; Beards, Stephanie; Arrojo, Manuel; Baudin, Grégoire; Olmeda, Ma Soledad; Frijda, Flora; Díaz-Caneja, Covadonga M; Sánchez, Emilio; Hubbard, Kathryn; Tripoli, Giada; Seminerio, Fabio; Pignon, Baptiste; Sartorio, Crocettarachele; Sanjuán, Julio; Kirkbride, James B; Cuadrado, Pedro; Amoretti, Silvia; Quigley, Harriet; Garcia-Portilla, Paz; Rapado, Marta; Marrazzo, Giovanna; Jiménez-López, Estela; Velthorst, Eva; Van Os, Jim; Bernardo, Miguel; Bernardo, Miquel; Matteis, Mario; Franke, Nathalie; González, Emiliano; Jongsma, Hannah E; Messchaart, Elles; Martínez, Covadonga; Díaz-Caneja, Covadonga M; Menezes, Paulo Rossi; Ferchiou, Aziz; Rodriguez, Victoria; Richard, Jean-Romain; Del-Ben, Cristina Marta; Shuhama, Rosana; Berardi, Domenico; Nacher, Juan; Roldán Díaz, Laura; Moltó, Ma Dolores; Marcelino Loureiro, Camila; Tosato, Sarah; Lynskey, Michael; Sham, Pak C; Rodríguez Solano, José Juan; Tortelli, Andrea; García Bernardo, Enrique; Arango, Celso; Jamain, Stéphane; Rutten, Bart Pf; Schürhoff, Franck; Termorshuizen, Fabian; Bonetto, Chiara; Sáiz, Pilar A.; Costas, Javier; Bobes, Julio; Selten, Jean-Paul; Lynskey, Michael; Leboyer, Marion; Menezes, Paulo Rossi; De Haan, Lieuwe; Ruggeri, Mirella; Carracedo, Angel; Szöke, Andrei; Lewis, Cathryn M; Quattrone, Diego; Cabrera, Bibiana; Sideli, Lucia.

In: THE LANCET. PSYCHIATRY, Vol. 6, 2019, pag. 427-436.

Risultato della ricerca: Article

Sartorio, C, Tripoli, G, Marrazzo, G, Ferraro, L, La Cascia, C, Seminerio, F, La Barbera, D, Di Forti, M, Tarricone, I, Parellada, M, Lorente-Rovira, E, Tronche, A-M, Cristofalo, D, Jones, PB, Freeman, TP, Sideli, L, González Peñas, J, Murray, RM, Stilo, SA, Van Der Ven, E, Charpeaud, T, Gayer-Anderson, C, Van Dam, D, López Montoya, G, Morgan, C, Beards, S, Arrojo, M, Baudin, G, Olmeda, MS, Frijda, F, Díaz-Caneja, CM, Sánchez, E, Hubbard, K, Tripoli, G, Seminerio, F, Pignon, B, Sartorio, C, Sanjuán, J, Kirkbride, JB, Cuadrado, P, Amoretti, S, Quigley, H, Garcia-Portilla, P, Rapado, M, Marrazzo, G, Jiménez-López, E, Velthorst, E, Van Os, J, Bernardo, M, Bernardo, M, Matteis, M, Franke, N, González, E, Jongsma, HE, Messchaart, E, Martínez, C, Díaz-Caneja, CM, Menezes, PR, Ferchiou, A, Rodriguez, V, Richard, J-R, Del-Ben, CM, Shuhama, R, Berardi, D, Nacher, J, Roldán Díaz, L, Moltó, MD, Marcelino Loureiro, C, Tosato, S, Lynskey, M, Sham, PC, Rodríguez Solano, JJ, Tortelli, A, García Bernardo, E, Arango, C, Jamain, S, Rutten, BP, Schürhoff, F, Termorshuizen, F, Bonetto, C, Sáiz, PA, Costas, J, Bobes, J, Selten, J-P, Lynskey, M, Leboyer, M, Menezes, PR, De Haan, L, Ruggeri, M, Carracedo, A, Szöke, A, Lewis, CM, Quattrone, D, Cabrera, B & Sideli, L 2019, 'The contribution of cannabis use to variation in the incidence of psychotic disorder across Europe (EU-GEI): a multicentre case-control study', THE LANCET. PSYCHIATRY, vol. 6, pagg. 427-436.
Sartorio, Crocettarachele ; Tripoli, Giada ; Marrazzo, Giovanna ; Ferraro, Laura ; La Cascia, Caterina ; Seminerio, Fabio ; La Barbera, Daniele ; Di Forti, Marta ; Tarricone, Ilaria ; Parellada, Mara ; Lorente-Rovira, Esther ; Tronche, Anne-Marie ; Cristofalo, Doriana ; Jones, Peter B ; Freeman, Tom P ; Sideli, Lucia ; González Peñas, Javier ; Murray, Robin M ; Stilo, Simona A ; Van Der Ven, Elsje ; Charpeaud, Thomas ; Gayer-Anderson, Charlotte ; Van Dam, Daniella ; López Montoya, Gonzalo ; Morgan, Craig ; Beards, Stephanie ; Arrojo, Manuel ; Baudin, Grégoire ; Olmeda, Ma Soledad ; Frijda, Flora ; Díaz-Caneja, Covadonga M ; Sánchez, Emilio ; Hubbard, Kathryn ; Tripoli, Giada ; Seminerio, Fabio ; Pignon, Baptiste ; Sartorio, Crocettarachele ; Sanjuán, Julio ; Kirkbride, James B ; Cuadrado, Pedro ; Amoretti, Silvia ; Quigley, Harriet ; Garcia-Portilla, Paz ; Rapado, Marta ; Marrazzo, Giovanna ; Jiménez-López, Estela ; Velthorst, Eva ; Van Os, Jim ; Bernardo, Miguel ; Bernardo, Miquel ; Matteis, Mario ; Franke, Nathalie ; González, Emiliano ; Jongsma, Hannah E ; Messchaart, Elles ; Martínez, Covadonga ; Díaz-Caneja, Covadonga M ; Menezes, Paulo Rossi ; Ferchiou, Aziz ; Rodriguez, Victoria ; Richard, Jean-Romain ; Del-Ben, Cristina Marta ; Shuhama, Rosana ; Berardi, Domenico ; Nacher, Juan ; Roldán Díaz, Laura ; Moltó, Ma Dolores ; Marcelino Loureiro, Camila ; Tosato, Sarah ; Lynskey, Michael ; Sham, Pak C ; Rodríguez Solano, José Juan ; Tortelli, Andrea ; García Bernardo, Enrique ; Arango, Celso ; Jamain, Stéphane ; Rutten, Bart Pf ; Schürhoff, Franck ; Termorshuizen, Fabian ; Bonetto, Chiara ; Sáiz, Pilar A. ; Costas, Javier ; Bobes, Julio ; Selten, Jean-Paul ; Lynskey, Michael ; Leboyer, Marion ; Menezes, Paulo Rossi ; De Haan, Lieuwe ; Ruggeri, Mirella ; Carracedo, Angel ; Szöke, Andrei ; Lewis, Cathryn M ; Quattrone, Diego ; Cabrera, Bibiana ; Sideli, Lucia. / The contribution of cannabis use to variation in the incidence of psychotic disorder across Europe (EU-GEI): a multicentre case-control study. In: THE LANCET. PSYCHIATRY. 2019 ; Vol. 6. pagg. 427-436.
@article{9943f5bc7a9543759f9e3879d3c45381,
title = "The contribution of cannabis use to variation in the incidence of psychotic disorder across Europe (EU-GEI): a multicentre case-control study",
abstract = "BackgroundCannabis use is associated with increased risk of later psychotic disorder but whether it affects incidence of the disorder remains unclear. We aimed to identify patterns of cannabis use with the strongest effect on odds of psychotic disorder across Europe and explore whether differences in such patterns contribute to variations in the incidence rates of psychotic disorder.MethodsWe included patients aged 18–64 years who presented to psychiatric services in 11 sites across Europe and Brazil with first-episode psychosis and recruited controls representative of the local populations. We applied adjusted logistic regression models to the data to estimate which patterns of cannabis use carried the highest odds for psychotic disorder. Using Europe-wide and national data on the expected concentration of Δ9-tetrahydrocannabinol (THC) in the different types of cannabis available across the sites, we divided the types of cannabis used by participants into two categories: low potency (THC <10{\%}) and high potency (THC ≥10{\%}). Assuming causality, we calculated the population attributable fractions (PAFs) for the patterns of cannabis use associated with the highest odds of psychosis and the correlation between such patterns and the incidence rates for psychotic disorder across the study sites.FindingsBetween May 1, 2010, and April 1, 2015, we obtained data from 901 patients with first-episode psychosis across 11 sites and 1237 population controls from those same sites. Daily cannabis use was associated with increased odds of psychotic disorder compared with never users (adjusted odds ratio [OR] 3·2, 95{\%} CI 2·2–4·1), increasing to nearly five-times increased odds for daily use of high-potency types of cannabis (4·8, 2·5–6·3). The PAFs calculated indicated that if high-potency cannabis were no longer available, 12·2{\%} (95{\%} CI 3·0–16·1) of cases of first-episode psychosis could be prevented across the 11 sites, rising to 30·3{\%} (15·2–40·0) in London and 50·3{\%} (27·4–66·0) in Amsterdam. The adjusted incident rates for psychotic disorder were positively correlated with the prevalence in controls across the 11 sites of use of high-potency cannabis (r = 0·7; p=0·0286) and daily use (r = 0·8; p=0·0109).InterpretationDifferences in frequency of daily cannabis use and in use of high-potency cannabis contributed to the striking variation in the incidence of psychotic disorder across the 11 studied sites. Given the increasing availability of high-potency cannabis, this has important implications for public health.",
author = "Crocettarachele Sartorio and Giada Tripoli and Giovanna Marrazzo and Laura Ferraro and {La Cascia}, Caterina and Fabio Seminerio and {La Barbera}, Daniele and {Di Forti}, Marta and Ilaria Tarricone and Mara Parellada and Esther Lorente-Rovira and Anne-Marie Tronche and Doriana Cristofalo and Jones, {Peter B} and Freeman, {Tom P} and Lucia Sideli and {Gonz{\'a}lez Pe{\~n}as}, Javier and Murray, {Robin M} and Stilo, {Simona A} and {Van Der Ven}, Elsje and Thomas Charpeaud and Charlotte Gayer-Anderson and {Van Dam}, Daniella and {L{\'o}pez Montoya}, Gonzalo and Craig Morgan and Stephanie Beards and Manuel Arrojo and Gr{\'e}goire Baudin and Olmeda, {Ma Soledad} and Flora Frijda and D{\'i}az-Caneja, {Covadonga M} and Emilio S{\'a}nchez and Kathryn Hubbard and Giada Tripoli and Fabio Seminerio and Baptiste Pignon and Crocettarachele Sartorio and Julio Sanju{\'a}n and Kirkbride, {James B} and Pedro Cuadrado and Silvia Amoretti and Harriet Quigley and Paz Garcia-Portilla and Marta Rapado and Giovanna Marrazzo and Estela Jim{\'e}nez-L{\'o}pez and Eva Velthorst and {Van Os}, Jim and Miguel Bernardo and Miquel Bernardo and Mario Matteis and Nathalie Franke and Emiliano Gonz{\'a}lez and Jongsma, {Hannah E} and Elles Messchaart and Covadonga Mart{\'i}nez and D{\'i}az-Caneja, {Covadonga M} and Menezes, {Paulo Rossi} and Aziz Ferchiou and Victoria Rodriguez and Jean-Romain Richard and Del-Ben, {Cristina Marta} and Rosana Shuhama and Domenico Berardi and Juan Nacher and {Rold{\'a}n D{\'i}az}, Laura and Molt{\'o}, {Ma Dolores} and {Marcelino Loureiro}, Camila and Sarah Tosato and Michael Lynskey and Sham, {Pak C} and {Rodr{\'i}guez Solano}, {Jos{\'e} Juan} and Andrea Tortelli and {Garc{\'i}a Bernardo}, Enrique and Celso Arango and St{\'e}phane Jamain and Rutten, {Bart Pf} and Franck Sch{\"u}rhoff and Fabian Termorshuizen and Chiara Bonetto and S{\'a}iz, {Pilar A.} and Javier Costas and Julio Bobes and Jean-Paul Selten and Michael Lynskey and Marion Leboyer and Menezes, {Paulo Rossi} and {De Haan}, Lieuwe and Mirella Ruggeri and Angel Carracedo and Andrei Sz{\"o}ke and Lewis, {Cathryn M} and Diego Quattrone and Bibiana Cabrera and Lucia Sideli",
year = "2019",
language = "English",
volume = "6",
pages = "427--436",
journal = "The Lancet Psychiatry",
issn = "2215-0366",
publisher = "Elsevier Ltd",

}

TY - JOUR

T1 - The contribution of cannabis use to variation in the incidence of psychotic disorder across Europe (EU-GEI): a multicentre case-control study

AU - Sartorio, Crocettarachele

AU - Tripoli, Giada

AU - Marrazzo, Giovanna

AU - Ferraro, Laura

AU - La Cascia, Caterina

AU - Seminerio, Fabio

AU - La Barbera, Daniele

AU - Di Forti, Marta

AU - Tarricone, Ilaria

AU - Parellada, Mara

AU - Lorente-Rovira, Esther

AU - Tronche, Anne-Marie

AU - Cristofalo, Doriana

AU - Jones, Peter B

AU - Freeman, Tom P

AU - Sideli, Lucia

AU - González Peñas, Javier

AU - Murray, Robin M

AU - Stilo, Simona A

AU - Van Der Ven, Elsje

AU - Charpeaud, Thomas

AU - Gayer-Anderson, Charlotte

AU - Van Dam, Daniella

AU - López Montoya, Gonzalo

AU - Morgan, Craig

AU - Beards, Stephanie

AU - Arrojo, Manuel

AU - Baudin, Grégoire

AU - Olmeda, Ma Soledad

AU - Frijda, Flora

AU - Díaz-Caneja, Covadonga M

AU - Sánchez, Emilio

AU - Hubbard, Kathryn

AU - Tripoli, Giada

AU - Seminerio, Fabio

AU - Pignon, Baptiste

AU - Sartorio, Crocettarachele

AU - Sanjuán, Julio

AU - Kirkbride, James B

AU - Cuadrado, Pedro

AU - Amoretti, Silvia

AU - Quigley, Harriet

AU - Garcia-Portilla, Paz

AU - Rapado, Marta

AU - Marrazzo, Giovanna

AU - Jiménez-López, Estela

AU - Velthorst, Eva

AU - Van Os, Jim

AU - Bernardo, Miguel

AU - Bernardo, Miquel

AU - Matteis, Mario

AU - Franke, Nathalie

AU - González, Emiliano

AU - Jongsma, Hannah E

AU - Messchaart, Elles

AU - Martínez, Covadonga

AU - Díaz-Caneja, Covadonga M

AU - Menezes, Paulo Rossi

AU - Ferchiou, Aziz

AU - Rodriguez, Victoria

AU - Richard, Jean-Romain

AU - Del-Ben, Cristina Marta

AU - Shuhama, Rosana

AU - Berardi, Domenico

AU - Nacher, Juan

AU - Roldán Díaz, Laura

AU - Moltó, Ma Dolores

AU - Marcelino Loureiro, Camila

AU - Tosato, Sarah

AU - Lynskey, Michael

AU - Sham, Pak C

AU - Rodríguez Solano, José Juan

AU - Tortelli, Andrea

AU - García Bernardo, Enrique

AU - Arango, Celso

AU - Jamain, Stéphane

AU - Rutten, Bart Pf

AU - Schürhoff, Franck

AU - Termorshuizen, Fabian

AU - Bonetto, Chiara

AU - Sáiz, Pilar A.

AU - Costas, Javier

AU - Bobes, Julio

AU - Selten, Jean-Paul

AU - Lynskey, Michael

AU - Leboyer, Marion

AU - Menezes, Paulo Rossi

AU - De Haan, Lieuwe

AU - Ruggeri, Mirella

AU - Carracedo, Angel

AU - Szöke, Andrei

AU - Lewis, Cathryn M

AU - Quattrone, Diego

AU - Cabrera, Bibiana

AU - Sideli, Lucia

PY - 2019

Y1 - 2019

N2 - BackgroundCannabis use is associated with increased risk of later psychotic disorder but whether it affects incidence of the disorder remains unclear. We aimed to identify patterns of cannabis use with the strongest effect on odds of psychotic disorder across Europe and explore whether differences in such patterns contribute to variations in the incidence rates of psychotic disorder.MethodsWe included patients aged 18–64 years who presented to psychiatric services in 11 sites across Europe and Brazil with first-episode psychosis and recruited controls representative of the local populations. We applied adjusted logistic regression models to the data to estimate which patterns of cannabis use carried the highest odds for psychotic disorder. Using Europe-wide and national data on the expected concentration of Δ9-tetrahydrocannabinol (THC) in the different types of cannabis available across the sites, we divided the types of cannabis used by participants into two categories: low potency (THC <10%) and high potency (THC ≥10%). Assuming causality, we calculated the population attributable fractions (PAFs) for the patterns of cannabis use associated with the highest odds of psychosis and the correlation between such patterns and the incidence rates for psychotic disorder across the study sites.FindingsBetween May 1, 2010, and April 1, 2015, we obtained data from 901 patients with first-episode psychosis across 11 sites and 1237 population controls from those same sites. Daily cannabis use was associated with increased odds of psychotic disorder compared with never users (adjusted odds ratio [OR] 3·2, 95% CI 2·2–4·1), increasing to nearly five-times increased odds for daily use of high-potency types of cannabis (4·8, 2·5–6·3). The PAFs calculated indicated that if high-potency cannabis were no longer available, 12·2% (95% CI 3·0–16·1) of cases of first-episode psychosis could be prevented across the 11 sites, rising to 30·3% (15·2–40·0) in London and 50·3% (27·4–66·0) in Amsterdam. The adjusted incident rates for psychotic disorder were positively correlated with the prevalence in controls across the 11 sites of use of high-potency cannabis (r = 0·7; p=0·0286) and daily use (r = 0·8; p=0·0109).InterpretationDifferences in frequency of daily cannabis use and in use of high-potency cannabis contributed to the striking variation in the incidence of psychotic disorder across the 11 studied sites. Given the increasing availability of high-potency cannabis, this has important implications for public health.

AB - BackgroundCannabis use is associated with increased risk of later psychotic disorder but whether it affects incidence of the disorder remains unclear. We aimed to identify patterns of cannabis use with the strongest effect on odds of psychotic disorder across Europe and explore whether differences in such patterns contribute to variations in the incidence rates of psychotic disorder.MethodsWe included patients aged 18–64 years who presented to psychiatric services in 11 sites across Europe and Brazil with first-episode psychosis and recruited controls representative of the local populations. We applied adjusted logistic regression models to the data to estimate which patterns of cannabis use carried the highest odds for psychotic disorder. Using Europe-wide and national data on the expected concentration of Δ9-tetrahydrocannabinol (THC) in the different types of cannabis available across the sites, we divided the types of cannabis used by participants into two categories: low potency (THC <10%) and high potency (THC ≥10%). Assuming causality, we calculated the population attributable fractions (PAFs) for the patterns of cannabis use associated with the highest odds of psychosis and the correlation between such patterns and the incidence rates for psychotic disorder across the study sites.FindingsBetween May 1, 2010, and April 1, 2015, we obtained data from 901 patients with first-episode psychosis across 11 sites and 1237 population controls from those same sites. Daily cannabis use was associated with increased odds of psychotic disorder compared with never users (adjusted odds ratio [OR] 3·2, 95% CI 2·2–4·1), increasing to nearly five-times increased odds for daily use of high-potency types of cannabis (4·8, 2·5–6·3). The PAFs calculated indicated that if high-potency cannabis were no longer available, 12·2% (95% CI 3·0–16·1) of cases of first-episode psychosis could be prevented across the 11 sites, rising to 30·3% (15·2–40·0) in London and 50·3% (27·4–66·0) in Amsterdam. The adjusted incident rates for psychotic disorder were positively correlated with the prevalence in controls across the 11 sites of use of high-potency cannabis (r = 0·7; p=0·0286) and daily use (r = 0·8; p=0·0109).InterpretationDifferences in frequency of daily cannabis use and in use of high-potency cannabis contributed to the striking variation in the incidence of psychotic disorder across the 11 studied sites. Given the increasing availability of high-potency cannabis, this has important implications for public health.

UR - http://hdl.handle.net/10447/348500

UR - https://www.thelancet.com/action/showPdf?pii=S2215-0366(19)30048-3

M3 - Article

VL - 6

SP - 427

EP - 436

JO - The Lancet Psychiatry

JF - The Lancet Psychiatry

SN - 2215-0366

ER -