Cannabis Use, Schizophrenia
Conditions
Brief summary
This study will recruit schizophrenia patients who use cannabis recreationally. Each participant will attend the laboratory on three occasions: an initial visit to check that they are safe to join the study and two days of testing. Participants will be administered, in a randomized order, a pre-treatment with either CBD (1000mg) orally or a matching placebo. On both experiments, participants will then inhale cannabis containing THC. The THC administration will follow a standardised inhalation procedure using a medical-grade vaporizer device. Participants will complete a series of tasks measuring cognition, psychosis, anxiety and other subjective experiences. The study will be carried out at the NIHR-Wellcome Trust Clinical Research Facility at King's College Hospital.
Interventions
Sponsors
King's College London
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
BASIC_SCIENCE
Masking
QUADRUPLE (Subject, Caregiver, Investigator, Outcomes Assessor)
Eligibility
Sex/Gender
ALL
Age
18 Years to 65 Years
Healthy volunteers
No
Inclusion criteria
* Age 18-65 years. * Clinical diagnosis of schizophrenia (i.e. documented as such in the patient's clinical records and satisfying ICD-10 criteria for F20) * Clinically stable for at least three months (since discharge from hospital, home treatment team, or prior clinical deterioration, and with agreement from the patient's responsible clinician) * Regular (at least weekly) cannabis use for the past 3 months or more * Evidence from either clinicians or from the patient that cannabis use exacerbates their symptoms or increases their risk of relapse * Treatment with regular doses of antipsychotic medication for at least 1 month, confirmed by a blood test at the baseline visit, and with the participant agreeing to be maintained at a stable dose over the course of the experiment * The participant agrees to abstain from cannabis use for at least 24hours prior to study visits * The participant is willing to have an intravenous cannula inserted to collect blood samples on experimental visits * Sufficiently fluent English * Providing written informed consent
Exclusion criteria
* Extreme cannabis use: participant is estimate to be using over 1gram of cannabis/day * Dependence on alcohol or illicit substances other than cannabis as defined by ICD-10 * Pregnancy (current or planned) or breastfeeding * Physical health disorder or another mental health disorder that the study psychiatrist judges may influence the patient's ability to tolerate the procedure, or that may alter the results of the study. * Taken part in any drug study within the last 3 months or taking part in another study over the course of the trial * Drug sensitivity/allergy to cannabis or Lorazepam * Unlikely to be able to complete the study sessions for any reason, as judged by the study psychiatrist Additional criteria which must be met on experimental visits: * Negative alcohol breath test * Negative urine drug screen (apart from cannabis and prescribed medication) * Negative urine pregnancy test * Stable mental state as judged by the study psychiatrist
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Hopkins Verbal Learning Test | Baseline visit; 20 mins post-THC | Delayed verbal recall |
| Positive and Negative Syndrome Scale | pre-CBD/placebo administration, and from immediately after THC inhalation until the end of study visit (i.e. 2-3 hours post-THC) | Positive Subscale |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Plasma 11-OH-THC concentration | pre-CBD/placebo, 90mins post CBD, and 0mins, 5mins, 15mins, +90mins post-THC | — |
| Plasma 6-OH-CBD concentration | pre-CBD/placebo, 90mins post CBD, and 0mins, 5mins, 15mins, +90mins post-THC | — |
| Plasma anandamide concentration | pre-CBD/placebo, 90mins post CBD, and 0mins, 5mins, 15mins, +90mins post-THC | — |
| State-Trait Anxiety Inventory | pre-CBD/placebo administration, pre-THC and 20mins post-THC | State Scale |
| Digit span | Baseline; 25 mins post-THC | Forward & Reverse |
| Hopkins Verbal Learning Test | Baseline; 20 mins post-THC | Immediate verbal recall |
| Positive and Negative Syndrome Scale | pre-CBD/placebo administration, and from immediately after THC inhalation until the end of study visit (i.e. 2-3 hours post-THC) | Negative Subscale |
| Visual analogue scales | pre-CBD/placebo, 90mins post CBD, pre-THC, and +10mins, +45mins, +90mins post-THC inhalation, and at the end of study visit (i.e. 2-3 hours post-THC) | * Feel drug effect * Like drug effect * Want more drug * Thinking clearly * Tired * Excited * Want to talk * Anxious * Relaxed * Happy * Irritable * Suspicious * Hearing voices * Dry mouth * Hungry |
| Plasma THC-COOH concentraion | pre-CBD/placebo, 90mins post CBD, and 0mins, 5mins, 15mins, +90mins post-THC | — |
| State Social Paranoia Scale | pre-CBD/placebo administration, and at the end of study visit (i.e. 2-3 hours post-THC) | — |
| Study drug preference | End of Experiment 2 | At the end of the final experimental visit (i.e. 2-3 hours post-THC), participants will be asked to order the two experimental visits according to which drug combination they found most pleasurable. |
| Advice Taking Task | Baseline visit; 30 mins post-THC | — |
| White Noise Task | Baseline visit; 50 mins post-THC | — |
| Plasma delta-9-tetrahydrocannabinol (THC) concentration | pre-CBD/placebo, 90mins post CBD, and 0mins, 5mins, 15mins, +90mins post-THC | — |
| Plasma cannabidiol (CBD) concentration | pre-CBD/placebo, 90mins post CBD, and 0mins, 5mins, 15mins, +90mins post-THC | — |
| Plasma 2-arachidonoylglycerol concentration. | pre-CBD/placebo, 90mins post CBD, and 0mins, 5mins, 15mins, +90mins post-THC | — |
| Psychotomimetic states inventory | pre-CBD/placebo administration, and at the end of study visit (i.e. 2-3 hours post-THC) | — |
| Plasma 11-COOH-THC concentration | pre-CBD/placebo, 90mins post CBD, and 0mins, 5mins, 15mins, +90mins post-THC | — |
Countries
United Kingdom
Outcome results
None listed