BACKGROUND: Although cannabis use after a first episode of psychosis has been associated with relapse, little is known about the determinants of this most preventable risk factor for relapse of psychosis. Here we aimed to study whether the effects on outcome vary depending on the type of cannabis consumed and usage pattern. METHODS: In this observational study, we prospectively recruited and followed up patients aged 18-65 years who presented with their first episode of psychosis to psychiatric services in south London, London, UK. Relapse of psychosis within 2 years after onset of psychosis was defined as risk of subsequent admission to hospital. We classified patients into different patterns of cannabis use based on continuity of use after onset of psychosis, potency of cannabis consumed, and frequency of use after the onset of their illness. We used multiple regression analyses (logistic or binominal) to compare the different cannabis use groups and propensity score analysis to validate the results. FINDINGS: Between April 12, 2002, and July 26, 2013, 256 patients presented with a first episode of psychosis. We did follow-up assessments for these patients until September, 2015. Simple analyses showed that former regular users of cannabis who stopped after the onset of psychosis had the most favourable illness course with regards to relapse. In multiple analysis, continued high-frequency users (ie, daily use in all 24 months) of high-potency (skunk-like) cannabis had the worst outcome, indexed as an increased risk for a subsequent relapse (odds ratio [OR] 3·28; 95% CI 1·22-9·18), more relapses (incidence rate ratio 1·77; 95% CI 0·96-3·25), fewer months until a relapse occurred (b -0·22; 95% CI -0·40 to -0·04), and more intense psychiatric care (OR 3·16; 95% CI 1·26-8·09) after the onset of psychosis. INTERPRETATION: Adverse effects associated with continued use of cannabis after the onset of a first episode of psychosis depend on the specific patterns of use. Possible interventions could focus on persuading cannabis-using patients with psychosis to reduce use or shift to less potent forms of cannabis. FUNDING: National Institute for Health Research (NIHR).
BACKGROUND: Although cannabis use after a first episode of psychosis has been associated with relapse, little is known about the determinants of this most preventable risk factor for relapse of psychosis. Here we aimed to study whether the effects on outcome vary depending on the type of cannabis consumed and usage pattern. METHODS: In this observational study, we prospectively recruited and followed up patients aged 18-65 years who presented with their first episode of psychosis to psychiatric services in south London, London, UK. Relapse of psychosis within 2 years after onset of psychosis was defined as risk of subsequent admission to hospital. We classified patients into different patterns of cannabis use based on continuity of use after onset of psychosis, potency of cannabis consumed, and frequency of use after the onset of their illness. We used multiple regression analyses (logistic or binominal) to compare the different cannabis use groups and propensity score analysis to validate the results. FINDINGS: Between April 12, 2002, and July 26, 2013, 256 patients presented with a first episode of psychosis. We did follow-up assessments for these patients until September, 2015. Simple analyses showed that former regular users of cannabis who stopped after the onset of psychosis had the most favourable illness course with regards to relapse. In multiple analysis, continued high-frequency users (ie, daily use in all 24 months) of high-potency (skunk-like) cannabis had the worst outcome, indexed as an increased risk for a subsequent relapse (odds ratio [OR] 3·28; 95% CI 1·22-9·18), more relapses (incidence rate ratio 1·77; 95% CI 0·96-3·25), fewer months until a relapse occurred (b -0·22; 95% CI -0·40 to -0·04), and more intense psychiatric care (OR 3·16; 95% CI 1·26-8·09) after the onset of psychosis. INTERPRETATION: Adverse effects associated with continued use of cannabis after the onset of a first episode of psychosis depend on the specific patterns of use. Possible interventions could focus on persuading cannabis-using patients with psychosis to reduce use or shift to less potent forms of cannabis. FUNDING: National Institute for Health Research (NIHR).
Authors: Delbert G Robinson; Nina R Schooler; Robert A Rosenheck; Haiqun Lin; Kyaw J Sint; Patricia Marcy; John M Kane Journal: Psychiatr Serv Date: 2019-05-14 Impact factor: 3.084
Authors: Karl C Alcover; Oladunni Oluwoye; Liat Kriegel; Sterling McPherson; Michael G McDonell Journal: Schizophr Res Date: 2019-08-02 Impact factor: 4.939
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Authors: Diego Quattrone; Laura Ferraro; Giada Tripoli; Caterina La Cascia; Harriet Quigley; Andrea Quattrone; Hannah E Jongsma; Simona Del Peschio; Giusy Gatto; Charlotte Gayer-Anderson; Peter B Jones; James B Kirkbride; Daniele La Barbera; Ilaria Tarricone; Domenico Berardi; Sarah Tosato; Antonio Lasalvia; Andrei Szöke; Celso Arango; Miquel Bernardo; Julio Bobes; Cristina Marta Del Ben; Paulo Rossi Menezes; Pierre-Michel Llorca; Jose Luis Santos; Julio Sanjuán; Andrea Tortelli; Eva Velthorst; Lieuwe de Haan; Bart P F Rutten; Michael T Lynskey; Tom P Freeman; Pak C Sham; Alastair G Cardno; Evangelos Vassos; Jim van Os; Craig Morgan; Ulrich Reininghaus; Cathryn M Lewis; Robin M Murray; Marta Di Forti Journal: Psychol Med Date: 2020-03-18 Impact factor: 7.723