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

March 16, 2026 updated by: Centre for Addiction and Mental Health
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

Status

Indicates the current recruitment status or the expanded access status.
Recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
60

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Locations

  • Canada
    • Ontario
      • Toronto, Ontario, Canada, M5T 1R8
        • Recruiting
        • Centre for Addiction and Mental Health
        • Contact:

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

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

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

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

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
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

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Standard deviation of lateral position
Time Frame: baseline
car 'weaving'
baseline
Standard deviation of lateral position
Time Frame: 15 minutes post smoking
car 'weaving'
15 minutes post smoking
Standard deviation of lateral position
Time Frame: 180 minutes post smoking
car 'weaving'
180 minutes post smoking

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Speed
Time Frame: baseline
Speed (in km) of the car
baseline
Speed
Time Frame: 15 minutes post smoking
Speed (in km) of the car
15 minutes post smoking
Speed
Time Frame: 180 minutes post smoking
Speed (in km) of the car
180 minutes post smoking
Reaction time
Time Frame: baseline
Time to hit the brake after introduction of an obstacle
baseline
Reaction time
Time Frame: 15 minutes post smoking
Time to hit the brake after introduction of an obstacle
15 minutes post smoking
Reaction time
Time Frame: 180 minutes post smoking
Time to hit the brake after introduction of an obstacle
180 minutes post smoking
Collisions
Time Frame: baseline
number of times the car hit an obstacle
baseline
Collisions
Time Frame: 15 minutes post smoking
number of times the car hit an obstacle
15 minutes post smoking
Collisions
Time Frame: 180 minutes post smoking
number of times the car hit an obstacle
180 minutes post smoking
Concentration of THC (ng/ml)
Time Frame: Baseline
Psychoactive component of cannabis
Baseline
Concentration of THC (ng/ml)
Time Frame: 15 minutes post smoking
Psychoactive component of cannabis
15 minutes post smoking
Useful Field of View Processing Speed
Time Frame: baseline
Mean threshold for discriminating stimuli presented in central vision
baseline
Useful Field of View Processing Speed
Time Frame: 60 minutes post smoking
Mean threshold for discriminating stimuli presented in central vision
60 minutes post smoking
Useful Field of View Processing Speed
Time Frame: 210 minutes post smoking
Mean threshold for discriminating stimuli presented in central vision
210 minutes post smoking
Useful Field of View Divided attention
Time Frame: baseline
Mean threshold for discriminating stimuli presented in central vision, with a concurrent perpheral target task
baseline
Useful Field of View Divided attention
Time Frame: 60 minutes
Mean threshold for discriminating stimuli presented in central vision, with a concurrent perpheral target task
60 minutes
Useful Field of View Divided attention
Time Frame: 210 minutes
Mean threshold for discriminating stimuli presented in central vision, with a concurrent perpheral target task
210 minutes
Useful Field of View Selective attention
Time Frame: baseline
Mean threshold for divided attention but with distractors
baseline
Useful Field of View Selective attention
Time Frame: 60 minutes
Mean threshold for divided attention but with distractors
60 minutes
Useful Field of View Selective attention
Time Frame: 210 minutes
Mean threshold for divided attention but with distractors
210 minutes
Trail making task
Time Frame: baseline
Cognitive assessment
baseline
Trail making task
Time Frame: 60 minutes post smoking
Cognitive assessment
60 minutes post smoking
Trail making task
Time Frame: 210 minutes post smoking
Cognitive assessment
210 minutes post smoking
Verbal free recall
Time Frame: baseline
Test of memory
baseline
Verbal free recall
Time Frame: 60 minutes post smoking
Test of memory
60 minutes post smoking
Verbal free recall
Time Frame: 210 minutes post smoking
Test of memory
210 minutes post smoking
Addiction Research Centre Inventory
Time Frame: baseline
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
Time Frame: 60 minutes post smoking
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
Time Frame: 210 minutes post smoking
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
Time Frame: baseline
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
Time Frame: 60 minutes post smoking
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
Time Frame: 210 minutes post smoking
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
Time Frame: baseline
test of mood on a scale from 0 to 100, with greater number indicating more agreement
baseline
Visual Analog Scale
Time Frame: 15 minutes post smoking
test of mood on a scale from 0 to 100, with greater number indicating more agreement
15 minutes post smoking
Visual Analog Scale
Time Frame: 60 minutes post smoking
test of mood on a scale from 0 to 100, with greater number indicating more agreement
60 minutes post smoking
Visual Analog Scale
Time Frame: 120 minutes post smoking
test of mood on a scale from 0 to 100, with greater number indicating more agreement
120 minutes post smoking
Visual Analog Scale
Time Frame: 180 minutes post smoking
test of mood on a scale from 0 to 100, with greater number indicating more agreement
180 minutes post smoking
Visual Analog Scale
Time Frame: 240 minutes post smoking
test of mood on a scale from 0 to 100, with greater number indicating more agreement
240 minutes post smoking
Visual Analog Scale
Time Frame: 300 minutes post smoking
test of mood on a scale from 0 to 100, with greater number indicating more agreement
300 minutes post smoking

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Centre for Addiction and Mental Health

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
October 7, 2024

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
February 1, 2027

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
March 1, 2027

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
August 25, 2022

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
August 30, 2022

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
September 2, 2022

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
March 17, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
March 16, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
March 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant 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

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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