Condition category
Mental and Behavioural Disorders
Date applied
Date assigned
Last edited
Retrospectively registered
Overall trial status
Recruitment status
No longer recruiting

Plain English Summary

Background and study aims
The purpose of the study is to find out the effect of Cannabidiol (CBD) on brain function. CBD comes from the cannabis plant, but does not produce a 'high' as its effects in humans are almost undetectable except for mild sedation at high doses. We want to learn more about the effect of CBD on the human mind in a simulated version of everyday life.

Who can participate?
The study is open to people who are currently attending the OASIS clinic, provided that you are not currently taking any psychiatric mediation. Participants can be of either sex, aged between 18 and 50, who are physically well, with no history of major illness.

What does the study involve?
The study will involve two blocks of 5 days each. On day 1 of each block you will be given a capsule containing either 300 mg CBD or placebo (dummy) in a random order. You will then be given a box containing the remaining doses, and will be asked to take a dose of CBD in the evenings for the next 3 days. On the 5th day of each block you will have the experimental session, where we will start by taking a small blood sample to test how much CBD is in your body. You will then be asked to complete some questionnaires and finally complete the virtual-reality bus ride, followed by a simulated public-speaking task. We will now and then measure your heart rate and take small saliva samples. The CBD week results will be compared with the placebo week results.

What are the possible benefits and risks of participating?
You will be paid £28 per day you are involved in the study, which is 10 days in total giving a maximum of £280. We will arrange for you to be collected from home by taxi and dropped back home at the end of each day. Some people may experience mild sedation after taking CBD, so we ask you not to drive, operate heavy machinery or engage in hazardous activities during the days you take any capsules. There are no documented effects of CBD on the heart or the nervous system aside from mild sedation, and no adverse effects have been recorded. It can very occasionally happen that some people experience a degree of nausea or disturbances in their vision after being in the virtual reality. Therefore if at any time you wish you stop, we will stop immediately.

Where is the study run from?
The study is run by the Institute of Psychiatry, Kings College London, UK.

When is study starting and how long is it expected to run for?
The study started in July 2013 and is expected to run until August 2015. It will be recruiting until January 2015.

Who is funding the study?
The study is funded by an unrestricted grant from GW Pharma, UK.

Who is the main contact?
Dr Paul Morrison

Trial website

Contact information



Primary contact

Dr Paul Morrison


Contact details

M5.06.02 Psychosis Studies
5th Floor
Main Building
Institute of Psychiatry
16 DeCrespigny Park
United Kingdom
0207 848 0057

Additional identifiers

EudraCT number number

Protocol/serial number


Study information

Scientific title

The effect of Cannabidiol (CBD) on paranoid cognitions in humans: a randomised controlled trial



Study hypothesis

The following hypothesis will be tested in an experimental laboratory setting:
1. CBD decreases perceived social threat and their endocrine sequelae.

Ethics approval

National Research Ethics Service (NRES) Committee London, 30/05/2013

Study design

Randomised cross-over design

Primary study design


Secondary study design

Randomised cross over trial

Trial setting


Trial type


Patient information sheet

Not available in web format, please use the contact details below to request a patient information sheet


Paranoid cognitions


All participants will receive Cannabidiol (CBD) on one occasion, and placebo on the other. The order of administrations will be randomised and double-blinded. The drugs will be administered as oral capsules, 3 x 100 mg being taken twice a day (total dose per day is 600 mg).

Intervention type



Not Applicable

Drug names


Primary outcome measures

1. Autonomic arousal using pulse and respiratory rates and saliva swabs to measure cortisol.
2. Paranoid thinking using the State-Social Paranoid Scale and the Cape-(state version).
3. Affective processing using the Beck Anxiety Inventory, the Bond and Lader Visual Analogue Scale and the Negative-Self-Statement-Scale.

Secondary outcome measures

Cognitive functioning using the Letter-Number-Span to measure working memory, and the Hopkins-Verbal-Learning-Task-Revised.

Overall trial start date


Overall trial end date


Reason abandoned


Participant inclusion criteria

1. Aged 18-50 years
2. English as first language
3. Patient at OASIS service

Participant type


Age group




Target number of participants


Participant exclusion criteria

1. Subjects who have been diagnosed with a major mental or physical illness (epilepsy, schizophrenia, bipolar disorder)
2. Subjects must not have had previous treatment with antipsychotic or mood stabilising drugs
3. Pregnancy
4. Drug/alcohol dependence

Recruitment start date


Recruitment end date



Countries of recruitment

United Kingdom

Trial participating centre

Institute of Psychiatry
United Kingdom

Sponsor information


King's College London (UK)

Sponsor details

Institute of Psychiatry
16 DeCrespigny Park
United Kingdom

Sponsor type




Funder type


Funder name

GW Pharmaceuticals (UK)

Alternative name(s)

Funding Body Type

Funding Body Subtype


Results and Publications

Publication and dissemination plan

Not provided at time of registration

Intention to publish date

Participant level data

Not provided at time of registration

Results - basic reporting

Publication summary

Publication citations

Additional files

Editorial Notes