Department of Social Genetics and Developmental Psychiatry, Institute of Psychiatry, Psychology & Neuroscience, King's College London, UK South London and Maudsley NHS Foundation Mental Health Trust, London, UK
Benjamin W. Bond
South London and Maudsley NHS Foundation Mental Health Trust, London, UK Department of Psychosis Studies, Institute of Psychiatry, Psychology & Neuroscience, King's College London, UK
Edoardo Spinazzola
South London and Maudsley NHS Foundation Mental Health Trust, London, UK Department of Psychosis Studies, Institute of Psychiatry, Psychology & Neuroscience, King's College London, UK
Giulia Trotta
Department of Social Genetics and Developmental Psychiatry, Institute of Psychiatry, Psychology & Neuroscience, King's College London, UK South London and Maudsley NHS Foundation Mental Health Trust, London, UK
Jodie Lynn
South London and Maudsley NHS Foundation Mental Health Trust, London, UK
Richard Malkin
South London and Maudsley NHS Foundation Mental Health Trust, London, UK Tees, Esk and Wear Valleys NHS Foundation Trust, Darlington, UK
Naba Kamran Siddiqui
South London and Maudsley NHS Foundation Mental Health Trust, London, UK
Sultan Demir
South London and Maudsley NHS Foundation Mental Health Trust, London, UK
Titilayomi Opadokun
South London and Maudsley NHS Foundation Mental Health Trust, London, UK
Department of Psychosis Studies, Institute of Psychiatry, Psychology & Neuroscience, King's College London, UK Department of Psychiatry, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR
Zhikun Li
Department of Social Genetics and Developmental Psychiatry, Institute of Psychiatry, Psychology & Neuroscience, King's College London, UK Centre for Neurodevelopmental Disorders New Hunt's House, Guy's Campus King's College London, UK
Andrea Quattrone
South London and Maudsley NHS Foundation Mental Health Trust, London, UK Institute of Biomedical Sciences Abel Salazar (ICBAS), University of Porto, Portugal
Gabriella Baxter
South London and Maudsley NHS Foundation Mental Health Trust, London, UK
Elizabeth Appiah-Kusi
South London and Maudsley NHS Foundation Mental Health Trust, London, UK
Tom P. Freeman
Addiction and Mental Health Group University of Bath, UK
Hannah Walsh
Department of Addictions, Institute of Psychiatry, Psychology & Neuroscience, King's College London, UK
GKT School of Medical Education, King's College London, UK
Daria Semikina
South London and Maudsley NHS Foundation Mental Health Trust, London, UK
Felicity Amberson-Jones
South London and Maudsley NHS Foundation Mental Health Trust, London, UK
Isabelle Austin-Zimmerman
Department of Social Genetics and Developmental Psychiatry, Institute of Psychiatry, Psychology & Neuroscience, King's College London, UK
Tim Meynen
Department of Social Genetics and Developmental Psychiatry, Institute of Psychiatry, Psychology & Neuroscience, King's College London, UK South London and Maudsley NHS Foundation Mental Health Trust, London, UK
Diego Quattrone
Department of Social Genetics and Developmental Psychiatry, Institute of Psychiatry, Psychology & Neuroscience, King's College London, UK South London and Maudsley NHS Foundation Mental Health Trust, London, UK
Robin M. Murray
South London and Maudsley NHS Foundation Mental Health Trust, London, UK Department of Psychosis Studies, Institute of Psychiatry, Psychology & Neuroscience, King's College London, UK
Background Cannabis use severely affects the outcome of people with psychotic disorders, yet there is a lack of treatments. To address this, in 2019 the National Health Service (NHS) Cannabis Clinic for Psychosis (CCP) was developed to support adults suffering from psychosis to reduce and/or stop their cannabis use. Aims Examine outcome data from the first 46 individuals to complete the CCP's intervention. Method The sample (N = 46) consisted of adults (aged ≥ 18) with psychosis under the care of the South London and Maudsley NHS Foundation Trust, referred to the CCP between January 2020 and February 2023, who completed their intervention by September 2023. Clinical and functional measures were collected before (T0) and after (T1) the CCP intervention (one-to-one sessions and peer group attendance). Primary outcomes were changes in the Cannabis Use Disorders Identification Test-Revised (CUDIT-R) score and pattern of cannabis use. Secondary outcomes included T0–T1 changes in measures of delusions, paranoia, depression, anxiety and functioning. Results A reduction in the mean CUDIT-R score was observed between T0 (mean difference = 17.10, 95% CI = 15.54–18.67) and T1, with 73.91% of participants achieving abstinence and 26.09% reducing the frequency and potency of their use. Significant improvements in all clinical and functional outcomes were observed, with 90.70% being in work or education at T1 compared with 8.70% at T0. The variance in CUDIT-R scores explained between 34 and 64% of the variance in our secondary measures. Conclusions The CCP intervention is a feasible strategy to support cannabis use cessation/reduction and improve clinical and functional outcomes of people with psychotic disorders.
