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Driving Under the InfluenceCASE-CTNCT05526196

Combined and Separate Effects of Cannabis and Tobacco: Psychomotor, Subjective and Physiological Outcomes

A study testing Cannabis, Tobacco and Cannabis tobacco in people with Driving Under the Influence, run by Centre for Addiction and Mental Health at 1 site in Canada.

Recruiting

Looking for participants now. Contact the study team or a site below to ask about taking part.

Sites and contacts
Official record
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Trial summary

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… Read more about this study

Who is it for?
Ages 19 to 45 yearsHealthy volunteers can take part
Conditions the study is for
Driving Under the Influence
What is being tested?
Cannabis, Tobacco and Cannabis tobacco
Could I receive a placebo?
Yes, some participants may receive a placebo
How many people
60 participants
Where
1 siteCanada
Study dates
7 Oct 2024to 1 Mar 2027
Phase
Interventional
Are there results?
Not yet: the study is under way

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 19 to 45 years
  • All sexes
  • Healthy volunteers accepted
  • Adult

Who may be able to join

  • • 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
Show all 13Show fewer
  • 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

Who cannot join

  • • 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)
Show all 14Show fewer
  • 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)

Trial locations and contacts

1 site in 1 country. Contact the study team or a site near you to ask about taking part.

Patricia Di Ciano contact

416-535-8501 ext. 34002

patricia.diciano@camh.ca

Canada1 site, 1 recruiting

  • Centre for Addiction and Mental Health

    Toronto, Ontario, M5T 1R8

    Patricia Di Ciano, PhD, 416 535-8501 ext. 34002, patricia.diciano@camh.ca

    Recruiting

Other trials in Canada

About this study

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.

Being tested
Cannabis, Tobacco, Cannabis tobacco, Placebo
Medical subject headings
Driving Under the Influence

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • CannabisDrug

    Dried flower cannabis cigarette with 22% THC

  • TobaccoDrug

    Dried flower cigarette with active nicotine

  • Cannabis tobaccoDrug

    Dried flower cigarette with active nicotine and cannabis

  • PlaceboDrug

    Dried flower cigarette with both placebo tobacco and cannabis

Study groups in NCT05526196
Study groupRoleWhat they receive
PlaceboOtherA cigarette containing placebo cannabis and placebo tobacco
Receives: Drug: Placebo
TobaccoOtherA cigarette with placebo cannabis and active tobacco
Receives: Drug: Tobacco
CannabisOtherA cigarette with active cannabis and placebo tobacco
Receives: Drug: Cannabis
Tobacco and cannabisOtherA cigarette with active cannabis and active tobacco
Receives: Drug: Cannabis tobacco

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Standard deviation of lateral position

    car 'weaving'

    Measured: baseline

  2. Standard deviation of lateral position

    car 'weaving'

    Measured: 15 minutes post smoking

  3. Standard deviation of lateral position

    car 'weaving'

    Measured: 180 minutes post smoking

Secondary outcomes (39)

  1. Speed

    Speed (in km) of the car

    Measured: baseline

  2. Speed

    Speed (in km) of the car

    Measured: 15 minutes post smoking

  3. Speed

    Speed (in km) of the car

    Measured: 180 minutes post smoking

  4. Reaction time

    Time to hit the brake after introduction of an obstacle

    Measured: baseline

  5. Reaction time

    Time to hit the brake after introduction of an obstacle

    Measured: 15 minutes post smoking

  6. Reaction time

    Time to hit the brake after introduction of an obstacle

    Measured: 180 minutes post smoking

  7. Collisions

    number of times the car hit an obstacle

    Measured: baseline

  8. Collisions

    number of times the car hit an obstacle

    Measured: 15 minutes post smoking

  9. Collisions

    number of times the car hit an obstacle

    Measured: 180 minutes post smoking

  10. Concentration of THC (ng/ml)

    Psychoactive component of cannabis

    Measured: Baseline

  11. Concentration of THC (ng/ml)

    Psychoactive component of cannabis

    Measured: 15 minutes post smoking

  12. Useful Field of View Processing Speed

    Mean threshold for discriminating stimuli presented in central vision

    Measured: baseline

  13. Useful Field of View Processing Speed

    Mean threshold for discriminating stimuli presented in central vision

    Measured: 60 minutes post smoking

  14. Useful Field of View Processing Speed

    Mean threshold for discriminating stimuli presented in central vision

    Measured: 210 minutes post smoking

  15. Useful Field of View Divided attention

    Mean threshold for discriminating stimuli presented in central vision, with a concurrent perpheral target task

    Measured: baseline

  16. Useful Field of View Divided attention

    Mean threshold for discriminating stimuli presented in central vision, with a concurrent perpheral target task

    Measured: 60 minutes

  17. Useful Field of View Divided attention

    Mean threshold for discriminating stimuli presented in central vision, with a concurrent perpheral target task

    Measured: 210 minutes

  18. Useful Field of View Selective attention

    Mean threshold for divided attention but with distractors

    Measured: baseline

  19. Useful Field of View Selective attention

    Mean threshold for divided attention but with distractors

    Measured: 60 minutes

  20. Useful Field of View Selective attention

    Mean threshold for divided attention but with distractors

    Measured: 210 minutes

  21. Trail making task

    Cognitive assessment

    Measured: baseline

  22. Trail making task

    Cognitive assessment

    Measured: 60 minutes post smoking

  23. Trail making task

    Cognitive assessment

    Measured: 210 minutes post smoking

  24. Verbal free recall

    Test of memory

    Measured: baseline

  25. Verbal free recall

    Test of memory

    Measured: 60 minutes post smoking

  26. Verbal free recall

    Test of memory

    Measured: 210 minutes post smoking

  27. 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

    Measured: baseline

  28. 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

    Measured: 60 minutes post smoking

  29. 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

    Measured: 210 minutes post smoking

  30. 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

    Measured: baseline

  31. 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

    Measured: 60 minutes post smoking

  32. 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

    Measured: 210 minutes post smoking

  33. Visual Analog Scale

    test of mood on a scale from 0 to 100, with greater number indicating more agreement

    Measured: baseline

  34. Visual Analog Scale

    test of mood on a scale from 0 to 100, with greater number indicating more agreement

    Measured: 15 minutes post smoking

  35. Visual Analog Scale

    test of mood on a scale from 0 to 100, with greater number indicating more agreement

    Measured: 60 minutes post smoking

  36. Visual Analog Scale

    test of mood on a scale from 0 to 100, with greater number indicating more agreement

    Measured: 120 minutes post smoking

  37. Visual Analog Scale

    test of mood on a scale from 0 to 100, with greater number indicating more agreement

    Measured: 180 minutes post smoking

  38. Visual Analog Scale

    test of mood on a scale from 0 to 100, with greater number indicating more agreement

    Measured: 240 minutes post smoking

  39. Visual Analog Scale

    test of mood on a scale from 0 to 100, with greater number indicating more agreement

    Measured: 300 minutes post smoking

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted2 Sep 2022
  2. Study start7 Oct 2024
  3. Primary completion1 Feb 2027 (estimated)
  4. Study completion1 Mar 2027 (estimated)

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase N/A
Primary purpose
Basic science
Allocation
Non-randomised
Intervention model
Crossover
Masking
Double blind
Who is masked
Participant, Investigator
Enrolment
60 participants (estimated)
IDs, dates and publications
ClinicalTrials.gov ID
NCT05526196
Sponsor's protocol ID
130-2021
Acronym
CASE-CT
Status last verified
Mar 2026
First submitted
25 Aug 2022
Last updated
17 Mar 2026
Results posted
No
FDA-regulated drug
No
FDA-regulated device
No
Individual data sharing
No

Questions about this trial

What is this clinical trial studying?

A study testing Cannabis, Tobacco and Cannabis tobacco in people with Driving Under the Influence, run by Centre for Addiction and Mental Health at 1 site in Canada.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 13 inclusion and 14 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: looking for participants now, as of the sponsor's last update on 17 Mar 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 1 site in Canada. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

Are results available for this study?

This study is still under way. Results are not available in the source record yet.

How can a doctor refer a patient or contact the research team?

Contact Patricia Di Ciano (416-535-8501 ext. 34002, patricia.diciano@camh.ca), or a site near the patient. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Standard deviation of lateral position (time frame: baseline). The study lists 3 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT05526196.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 17 Mar 2026.

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