Sussex Psychosis Research interest Group (SPRiG)

CIRCLE Contingency Management for Cannabis Use

Background:Black circle on white

Cannabis is the most commonly used drug for people who experience unshared perceptions, unusual beliefs and worrying experiences (also known as ‘psychosis’). Using cannabis when you have or have had psychosis can have negative consequences. It can increase the chance of future episodes of psychosis and can make symptoms such as paranoia more likely. It can also make it more difficult for people to carry on with or get back into work and social activity.

Giving up cannabis can be difficult though. Mental health professionals and researchers have struggled to find effective ways of helping people to do this. Treatments such as motivational interviewing and Cognitive Behavioural Therapy (CBT) have been tested but do not seem to be very effective. A newer treatment, contingency management (CM) has been found effective in helping people to change other behaviours, for example, taking medication, and losing weight.

Contingency management means that people are rewarded for attending an appointment and providing a sample (such as urine) which shows they have not used cannabis. The CIRCLE study is investigating how effective contingency management is at helping young people experiencing a first episode of psychosis to reduce the negative effects of problematic cannabis use.



CIRCLE is a Randomised Controlled Trial (RCT) because we do not know whether contingency management works better than the same treatment young people with psychosis usually receive for problems with cannabis use. An RCT means that people are randomly selected to get the new treatment or treatment as usual. Everyone has a 50% chance of being in either group. This helps us to compare the treatments and work out which one works best.

One group will receive contingency management. Cannabis use will be evaluated in both groups using research assessments and analysis of urine samples. Both groups will receive an educational intervention designed to help them reduce their problematic cannabis use. This intervention has six modules which include videos and quizzes.



Results of the trial will be disseminated in a number of ways: presentations at conferences, publications in academic journals and relevant magazines, reports to funding bodies, governments, and will be available on the internet. Results will include whether contingency management seems to help people reduce their cannabis use and whether this seems to help with preventing a relapse of psychosis. The cost-effectiveness of the intervention will also be worked out.



CIRCLE is running in other areas of the UK already. It is due to start in Sussex within the next few months.

This study is supported by funding from the National Institute of Mental Health and the Department of Health, UK.

If you want more information on this project please contact Kelly Humphryes ( or Leila Hughes (