Research project

CBT for cannabis related psychosis

Project overview

Using cannabis increases the risk of psychosis. This includes hallucinations (seeing or hearing things that aren't there) and delusions (e.g., paranoia – thinking that others are trying to harm us). Most people who use cannabis do not develop psychosis, and it's not fully understood why cannabis leads to psychosis in some people but not others. Around a third of people with 'first episode psychosis' use cannabis, and people with psychosis who use cannabis have worse outcomes – more severe symptoms and more hospitalisations. Cannabis can also be used to self-medicate, leading to a vicious circle of more cannabis use and more severe psychosis.

We are working with people with psychosis, their family and friends, and NHS clinicians, to develop psychological interventions to improve recovery outcomes for people with cannabis related psychosis. Our work focuses on key psychological processes (thinking patterns) – blaming others for unusual experiences (e.g., believing that somebody is playing a trick on me if I hear a voice), and getting caught up in difficult thoughts (e.g., not being able to stop thinking about my fears). With an understanding of these thinking patterns, we can support people to make informed decisions about cannabis use, and minimise the impact of cannabis related psychosis.


Lead researcher

Professor Katherine Newman-Taylor

Professorial Fellow-Education

Research interests

  • CBT and mindfulness for psychosis
  • Attachment based interventions for psychosis
  • Recovery approaches to living well with severe mental ill-health
Connect with Katherine

Collaborating research institutes, centres and groups