Cannabis withdrawal: a PET study of endocannabinoid metabolism

Centre for Addiction and Mental Health (CAMH), Campbell Family Mental Health Research Institute

We are interested in understanding the cause of cannabis withdrawal syndrome and how it affects the brain. We are looking for participants who are 19-65 years of age who regularly use cannabis are willing to abstain from using cannabis for approximately 1 week.

More information may be found at:

Your Impact

The objective of the proposed study is to use PET imaging using a tracer ([C-11] CURB) to visualize a protein in the brain (FAAH). We want to investigate whether FAAH levels in the brain contribute to withdrawal symptoms.This study will provide the first long term data on how cannabis related molecule metabolize in the brain during metabolism cannabis withdrawal.

Eligibility Criteria

All genders

19 to 65 years old

You must be 19-65 years

You must have recently experienced problems with excessive cannabis use - you must use cannabis everyday

You must not have an unstable medical condition

You must not have current psychiatric disorders

You must not have past or current neurological illness or head trauma

You must not have a history of suicide attempts or suicidality

You must not have metal implants in your body

You must not be pregnant or breastfeeding

You cannot have claustrophobia

Your exposure to radiation in the past 12 months cannot exceed the permissible limit for subjects participating in research

Study Tasks

Session 1: We will obtain your consent and screen you for suitability for the study (about four hours).
Session 2: •Each MRI scan lasts approximately 2 hours. This may be done on the same day or separate day as the PET scan(s).
Session 3/4: Each PET scan lasts approximately 4 hours. During the scan(s) we will collect blood samples needed for the PET, but also to measure inflammatory protein levels. We will ask you to fill out some questionnaires and complete some memory/ decision making tasks on this day. Your 2nd PET scan will take place ~1 week after the 1st PET scan.
Between PET scan 1 and PET scan 2 you will be enrolled in abstinence monitoring (~1hr) sessions to help you maintain abstinence.





Activity and Time

Health and Wellness

Clinical Trial


30 minute(s) - 4 hour(s) per session

4 session(s)

The study has three parts: - An in-person interview - Two - three MRI sessions - Two - three positron emission tomography (PET) scans - Abstinence monitoring sessions in between PET scans (~1hr per session)



All meals on scan days covered


All transportation covered e.g. round trip public transportation and in special occasions taxis and Ubers

Study Address

250 College St Toronto, Ontario, Canada, M5T 1R8

Posting date: Feb 24, 2020