Combined and Separate Effects of Cannabis and Tobacco: Psychomotor, Subjective and Physiological Outcomes (CASE-CT)

Co-administration of cannabis and tobacco is a common practice, but there is little experimental evidence aimed at understanding the reasons for this prevalence. Some preliminary evidence suggests that tobacco may actually counteract the cognitive-impairing effects of cannabis, and may also increase the subjective ('liking') effects of cannabis, but results are inconclusive. Further, there are no studies into the effects of tobacco on other cannabis-related harms such as driving, or on the ability of tobacco to alter the blood levels of THC, the chemical responsible for the psychoactive properties of cannabis. The purpose of the present study will be to evaluate the effects of tobacco, cannabis or combinations of tobacco and cannabis on driving, cognition, subjective effects and blood THC. Driving will be assessed using a state-of-the-art driving simulator that allows for the safe and objective measurement of the effects of intoxicating substances on driving. Participants will be regular users of cannabis and will be invited to the lab for four counterbalanced test sessions. In these test sessions they will drive the simulator and undergo cognitive tests before and after smoking: 1) cannabis; 2) tobacco; 3) cannabis + tobacco; or 4) placebo. Outcomes will be measured at several time points after smoking the product. Participants will also give blood for determination of levels of THC, and will complete subjective effects questionnaires both before and after smoking the cigarette. This study will be one of the first experimental laboratory studies of the reasons behind co-administration of tobacco and cannabis.

Study Overview

• Status: Recruiting
• Conditions: Driving Under the Influence
• Intervention / Treatment: Drug: Placebo; Drug: Tobacco; Drug: Cannabis; Drug: Cannabis tobacco

• Study Type: Interventional
• Enrollment (Estimated): 60
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Patricia Di Ciano; Phone Number: 34002 416-535-8501; Email: patricia.diciano@camh.ca

Study Locations

• Canada
  • Ontario
    • Toronto, Ontario, Canada, M5T 1R8
      • Recruiting
      • Centre for Addiction and Mental Health
      • Contact: Patricia Di Ciano, PhD; Phone Number: 34002 416 535-8501; Email: patricia.diciano@camh.ca

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 15 years to 41 years (Adult)
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• • Adults aged 19 years to 45 years (to control for the effects of age on cognition)

  • Smoke or vape cannabis at least once a month but no more than 4 times a week (to avoid enrolling people with cannabis use disorder who may experience withdrawal when asked to abstain from cannabis)
  • Experience with smoked cannabis in the past year
  • Report use of at least 100 cigarettes in their lifetime to ensure familiarity with the tobacco used in the present study
  • Use of any nicotine (smoked, vaped, etc) in the past year
  • G2 or full G driver's licence for at least a year
  • Willing to abstain from alcohol and other drugs (other than drugs required for treatment of a medical condition) for 48 hours prior to study session
  • Normal heart rate and blood pressure as determined by the QI (because cannabis and tobacco increase heart rate)
  • Normal ECG (because cannabis and tobacco increase heart rate)
  • Willing to abstain from cannabis for 72 hours prior to the test session and from smoking tobacco for 12 hours
  • Willing to use an accepted form of contraception during the study (both males and females)
  • Past lifetime experience with co-use of cannabis or tobacco (either simultaneous or concurrent)
  • Provides written and informed consent

Exclusion Criteria:

• • Use of psychoactive medications or drugs

  • Current alcohol or other substance use disorder, including cannabis (as assessed with the SCID)
  • Current or past nicotine dependence (to avoid precipitating a relapse)
  • Withdrawal symptoms as assessed with the Marijuana Withdrawal Checklist [57, 58]
  • A score of less than 10 on the Clinical Institute Withdrawal Assessment for Alcohol (CIWA-Ar) [59]
  • Family history of schizophrenia or psychosis (to avoid giving cannabis to anyone with a predisposition to psychosis)
  • Respiratory illnesses (due to the smoked route of administration in this study)
  • Any serious medical condition precluding participation as judged by the responsible study physician
  • Pregnancy or breastfeeding
  • Negative urine screen for cannabis at eligibility assessment (to ensure experience with cannabis)
  • Neurological disorders that may affect cognitive function
  • Treatment-seeking for tobacco or cannabis use
  • Use of more than 5 cigarettes a day (to avoid confound of the effects of chronic smoking on measures)
  • Concomitant therapy with sedative-hypnotics or other psychoactive drugs (counter-indicated with cannabis)

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Non-Randomized
• Interventional Model: Crossover Assignment
• Masking: Double

Number of Arms

4

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Other: Placebo; A cigarette containing placebo cannabis and placebo tobacco	Drug: Placebo; Dried flower cigarette with both placebo tobacco and cannabis
Other: Tobacco; A cigarette with placebo cannabis and active tobacco	Drug: Tobacco; Dried flower cigarette with active nicotine
Other: Cannabis; A cigarette with active cannabis and placebo tobacco	Drug: Cannabis; Dried flower cannabis cigarette with 22% THC
Other: Tobacco and cannabis; A cigarette with active cannabis and active tobacco	Drug: Cannabis tobacco; Dried flower cigarette with active nicotine and cannabis

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Standard deviation of lateral position	car 'weaving'	baseline
Standard deviation of lateral position	car 'weaving'	15 minutes post smoking
Standard deviation of lateral position	car 'weaving'	180 minutes post smoking

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Speed	Speed (in km) of the car	baseline
Speed	Speed (in km) of the car	15 minutes post smoking
Speed	Speed (in km) of the car	180 minutes post smoking
Reaction time	Time to hit the brake after introduction of an obstacle	baseline
Reaction time	Time to hit the brake after introduction of an obstacle	15 minutes post smoking
Reaction time	Time to hit the brake after introduction of an obstacle	180 minutes post smoking
Collisions	number of times the car hit an obstacle	baseline
Collisions	number of times the car hit an obstacle	15 minutes post smoking
Collisions	number of times the car hit an obstacle	180 minutes post smoking
Concentration of THC (ng/ml)	Psychoactive component of cannabis	Baseline
Concentration of THC (ng/ml)	Psychoactive component of cannabis	15 minutes post smoking
Useful Field of View Processing Speed	Mean threshold for discriminating stimuli presented in central vision	baseline
Useful Field of View Processing Speed	Mean threshold for discriminating stimuli presented in central vision	60 minutes post smoking
Useful Field of View Processing Speed	Mean threshold for discriminating stimuli presented in central vision	210 minutes post smoking
Useful Field of View Divided attention	Mean threshold for discriminating stimuli presented in central vision, with a concurrent perpheral target task	baseline
Useful Field of View Divided attention	Mean threshold for discriminating stimuli presented in central vision, with a concurrent perpheral target task	60 minutes
Useful Field of View Divided attention	Mean threshold for discriminating stimuli presented in central vision, with a concurrent perpheral target task	210 minutes
Useful Field of View Selective attention	Mean threshold for divided attention but with distractors	baseline
Useful Field of View Selective attention	Mean threshold for divided attention but with distractors	60 minutes
Useful Field of View Selective attention	Mean threshold for divided attention but with distractors	210 minutes
Trail making task	Cognitive assessment	baseline
Trail making task	Cognitive assessment	60 minutes post smoking
Trail making task	Cognitive assessment	210 minutes post smoking
Verbal free recall	Test of memory	baseline
Verbal free recall	Test of memory	60 minutes post smoking
Verbal free recall	Test of memory	210 minutes post smoking
Addiction Research Centre Inventory	Test of mood with 53 true-false questions that are summed to produce a measure of the intensity of mood, with higher scores reflecting greater mood	baseline
Addiction Research Centre Inventory	Test of mood with 53 true-false questions that are summed to produce a measure of the intensity of mood, with higher scores reflecting greater mood	60 minutes post smoking
Addiction Research Centre Inventory	Test of mood with 53 true-false questions that are summed to produce a measure of the intensity of mood, with higher scores reflecting greater mood	210 minutes post smoking
Profile of Mood States	Test of mood with 76 items with a five point scale that are summed to produce a measure of the intensity of mood, with higher scores indicating more agreemen	baseline
Profile of Mood States	Test of mood with 76 items with a five point scale that are summed to produce a measure of the intensity of mood, with higher scores indicating more agreemen	60 minutes post smoking
Profile of Mood States	Test of mood with 76 items with a five point scale that are summed to produce a measure of the intensity of mood, with higher scores indicating more agreemen	210 minutes post smoking
Visual Analog Scale	test of mood on a scale from 0 to 100, with greater number indicating more agreement	baseline
Visual Analog Scale	test of mood on a scale from 0 to 100, with greater number indicating more agreement	15 minutes post smoking
Visual Analog Scale	test of mood on a scale from 0 to 100, with greater number indicating more agreement	60 minutes post smoking
Visual Analog Scale	test of mood on a scale from 0 to 100, with greater number indicating more agreement	120 minutes post smoking
Visual Analog Scale	test of mood on a scale from 0 to 100, with greater number indicating more agreement	180 minutes post smoking
Visual Analog Scale	test of mood on a scale from 0 to 100, with greater number indicating more agreement	240 minutes post smoking
Visual Analog Scale	test of mood on a scale from 0 to 100, with greater number indicating more agreement	300 minutes post smoking

Collaborators and Investigators

• Sponsor: Centre for Addiction and Mental Health

Study record dates

Study Major Dates

• Study Start (Actual): October 7, 2024
• Primary Completion (Estimated): February 1, 2027
• Study Completion (Estimated): March 1, 2027

Study Registration Dates

• First Submitted: August 25, 2022
• First Submitted That Met QC Criteria: August 30, 2022
• First Posted (Actual): September 2, 2022

Study Record Updates

• Last Update Posted (Actual): March 17, 2026
• Last Update Submitted That Met QC Criteria: March 16, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Behavior; Criminal Behavior; Dangerous Behavior; Driving Under the Influence; Manufactured Materials; Technology, Industry, and Agriculture; Smoking Devices; Tobacco Products; nabiximols
• Other Study ID Numbers: 130-2021

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No