Cannabis Effects on Driving Performance

(ADCUF Trial)

Overseen By Gina Stoduto

Age: 18 - 65

Sex: Any

Trial Phase: Academic

Sponsor: Centre for Addiction and Mental Health

Must not be taking: Sedatives, Psychoactive drugs, Antihypertensives

Disqualifiers: Therapeutic cannabis, Psychiatric conditions, Substance use disorder, others

No Placebo Group All trial participants will receive the active study treatment (no placebo)

Compensation: Varies

Number of Visits: 2

128 Participants Needed

Trial Summary

Will I have to stop taking my current medications?

The trial requires participants to stop using any drugs not prescribed for medical purposes for 48 hours before practice and test sessions. If you are a regular user of medications that affect brain function, you may not be eligible to participate.

What does research say about the effectiveness of cannabis on driving performance?

Research shows that cannabis, especially when it contains THC, can impair driving abilities, but the extent of impairment depends on the dose and method of consumption. Studies found no significant differences in driving ability when using low-THC, CBD-rich cannabis compared to a placebo. ^{1 2 3 4 5}

Is cannabis safe for humans, particularly in relation to driving performance?

Research shows that cannabis, especially THC, can impair driving abilities, but the effects depend on the dose, method of use, and individual tolerance. CBD does not seem to impair cognitive or psychomotor functions, but more studies are needed to confirm its safety in driving. Participants should avoid driving for 8 hours if they feel 'high' after using cannabis. ^{1 2 6 7 8}

How does this drug affect driving performance compared to other treatments?

This study focuses on the effects of cannabis, specifically the components THC and CBD, on driving performance. Unlike other treatments, cannabis contains THC, which is known to impair driving ability, while CBD does not seem to cause such impairment. The unique aspect of this study is the investigation of how different ratios of THC and CBD in cannabis affect driving, which is not typically considered in other treatments for driving performance. ^{1 2 7 9 10}

What is the purpose of this trial?

Epidemiological studies suggest that the use of cannabis is associated with an increase in the risk of motor vehicle collisions. It is also known that younger users may be at increased risk for motor vehicle collisions. Further, the frequency with which cannabis is used may be an important variable in determining the effects of cannabis on driving. The purpose of the present study will be to investigate the effects of cannabis on simulated driving in young as compared to middle-aged drivers. Half of the participants will be occasional users of cannabis and half will be frequent users of cannabis.

Research Team

Christine Wickens, PhD

Principal Investigator

Centre for Addiction and Mental Health

Eligibility Criteria

This trial is for occasional or frequent cannabis users aged 19-25 or 35-45 with a valid driver's license. Participants must not use alcohol or drugs other than prescribed ones before sessions and live in the Toronto area. Pregnant women, those with certain health conditions, and regular users of brain-affecting meds cannot join.

Inclusion Criteria

I use smoked cannabis recreationally, up to 2 times a week or 5+ times but not every day.

Willing to abstain from all other drugs not prescribed for medical purposes for the duration of the study

I have had a full driver's license for at least 12 months.

Exclusion Criteria

I am not pregnant or breastfeeding.

I have a mental health condition that makes cannabis use unsafe for me.

Urine toxicology screens negative for cannabis upon Eligibility Assessment

Timeline

Screening

Participants are screened for eligibility to participate in the trial

2-4 weeks

Test Sessions

Participants attend two test sessions where they drive a simulator before and after smoking a cannabis or placebo cigarette. Blood samples and cognitive tasks are conducted.

2 sessions

2 visits (in-person)

Follow-up

Participants are monitored for safety and effectiveness after the test sessions, including cognitive and physiological assessments.

4 weeks

Treatment Details

Interventions

• Cannabis
• Placebos

Trial Overview The study examines how cannabis affects simulated driving performance in young versus middle-aged drivers. It compares the effects between occasional and frequent cannabis users using placebos as controls to understand age-related differences in impairment.

Participant Groups

Group I: Age group 35 to 45 Experimental Treatment 2 Interventions

Participants will complete two sessions: one where they drive the simulator before and after smoking a placebo cannabis cigarette (\<1% THC), the other where they drive the simulator before and after smoking an active cannabis cigarette (15% ± 5% THC).

Group II: Age group 19 to 25 Experimental Treatment 2 Interventions

Participants will complete two sessions: one where they drive the simulator before and after smoking a placebo cannabis cigarette (\<1% THC), the other where they drive the simulator before and after smoking an active cannabis cigarette (15% ± 5% THC).

Who Is Running the Clinical Trial?

Centre for Addiction and Mental Health

Lead Sponsor

Trials

388

Recruited

84,200+

Findings from Research

In a study involving 74 healthy adult volunteers, vaporization of low-THC, CBD-rich cannabis products did not significantly impair driving-related abilities compared to a placebo, suggesting that these products may be safe for driving.

THC levels in the blood peaked shortly after consumption but dropped below detectable levels within 1.5 hours for most participants, although some still had detectable THC up to 5 hours later, which could have legal implications for drivers.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Effect of vaporizing cannabis rich in cannabidiol on cannabinoid levels in blood and on driving ability - a randomized clinical trial. Egloff, L., Frei, P., Gerlach, K., et al.[2023]

Acute use of tetrahydrocannabinol (THC) significantly impairs certain driving abilities, although the effects are generally modest, as shown by simulator and road course studies.

Factors such as dose, delivery method, and individual tolerance influence the level of impairment, while the role of cannabidiol in mitigating THC-induced impairment remains unclear and requires further research.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Cannabis and driving ability. Sevigny, EL.[2022]

This study will assess the effects of both oral and vaporized cannabis on driving performance, cognitive abilities, and field sobriety in healthy adults, involving 64 participants across two double-blind, placebo-controlled trials.

By examining the impact of cannabis alone and in combination with alcohol, the research aims to enhance understanding of impairment levels, which could influence public policy and law enforcement standards regarding cannabis and alcohol use.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

The effects of oral and vaporized cannabis alone, and in combination with alcohol, on driving performance using the STISIM driving simulator: A two-part, double-blind, double-dummy, placebo-controlled, randomized crossover clinical laboratory protocol. Zamarripa, CA., Novak, MD., Weerts, EM., et al.[2023]

High doses of cannabis significantly impaired driving performance more than lower doses, while alcohol had minimal effects and did not enhance impairment when combined with cannabis.

Both substances increased speed and variability in driving, but high-dose cannabis led to decreased mean speed and longer reaction times, highlighting the need for further research on their individual effects on driving safety.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

The effects of cannabis and alcohol on simulated arterial driving: Influences of driving experience and task demand. Lenné, MG., Dietze, PM., Triggs, TJ., et al.[2022]

Cannabis use has significantly increased over the past 15 years, and it is the most commonly detected substance in drivers suspected of drug impairment, highlighting a public safety concern.

Experimental studies confirm that cannabis impairs psychomotor performance, especially at high doses or when combined with alcohol, necessitating better models to interpret blood cannabinoid levels in relation to driving impairment.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

[Cannabis and automobile driving]. Ménétrey, A., Augsburger, M., Giroud, C., et al.[2008]

Medical marijuana can impair driving performance and increase the risk of motor vehicle collisions, similar to other medications that affect psychomotor function, highlighting the need for healthcare providers to inform patients about these risks before prescribing it.

Patients using medical marijuana should avoid driving for at least 8 hours after feeling a 'high' and be cautious of the combined effects with alcohol and other psychoactive substances, emphasizing the importance of public safety in the context of increasing medical marijuana use.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Medical marijuana and driving: a review. Neavyn, MJ., Blohm, E., Babu, KM., et al.[2022]

This study will assess the effects of cannabidiol (CBD) on driving performance and cognitive function in 30 healthy individuals, using a randomized, double-blind, placebo-controlled design to ensure reliable results.

The research aims to determine if CBD causes any impairment in driving, comparing its effects to a placebo, and will also investigate whether CBD could lead to false-positive drug tests for Δ9-THC, ensuring safety for drivers using CBD.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

The effect of cannabidiol on simulated car driving performance: A randomised, double-blind, placebo-controlled, crossover, dose-ranging clinical trial protocol. McCartney, D., Benson, MJ., Suraev, AS., et al.[2021]

Vaporized THC-dominant and THC/CBD-equivalent cannabis significantly impaired driving performance, as indicated by increased lane weaving (measured by standard deviation of lateral position) compared to placebo, particularly 40 to 100 minutes after consumption.

CBD-dominant cannabis did not show significant impairment compared to placebo, suggesting it may not affect driving ability; however, the study notes that the tested doses may not reflect typical usage patterns.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Effect of Cannabidiol and Δ9-Tetrahydrocannabinol on Driving Performance: A Randomized Clinical Trial. Arkell, TR., Vinckenbosch, F., Kevin, RC., et al.[2021]

In a study with 14 healthy volunteers, both THC-dominant and THC/CBD equivalent cannabis impaired driving performance, particularly increasing lane weaving, indicating that both types can negatively affect driving safety.

Interestingly, the THC/CBD equivalent cannabis led to higher peak plasma THC levels and caused greater impairment on certain cognitive tasks compared to THC-dominant cannabis, suggesting that CBD may not mitigate THC's adverse effects and could potentially worsen them.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Cannabidiol (CBD) content in vaporized cannabis does not prevent tetrahydrocannabinol (THC)-induced impairment of driving and cognition. Arkell, TR., Lintzeris, N., Kevin, RC., et al.[2022]

A study using a driving simulator and real driving conditions found that THC significantly impairs driving performance, causing increased drowsiness and instability in vehicle control.

The driving simulator was more sensitive in detecting THC's effects on driving, suggesting it can effectively predict driving safety after drug use.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Cannabis smoking impairs driving performance on the simulator and real driving: a randomized, double-blind, placebo-controlled, crossover trial. Micallef, J., Dupouey, J., Jouve, E., et al.[2019]

References

1. Germany pubmed.ncbi.nlm.nih.gov

Effect of vaporizing cannabis rich in cannabidiol on cannabinoid levels in blood and on driving ability - a randomized clinical trial. [2023]

2. Netherlands pubmed.ncbi.nlm.nih.gov

Cannabis and driving ability. [2022]

3. Switzerland pubmed.ncbi.nlm.nih.gov

The effects of oral and vaporized cannabis alone, and in combination with alcohol, on driving performance using the STISIM driving simulator: A two-part, double-blind, double-dummy, placebo-controlled, randomized crossover clinical laboratory protocol. [2023]

4. England pubmed.ncbi.nlm.nih.gov

The effects of cannabis and alcohol on simulated arterial driving: Influences of driving experience and task demand. [2022]

5. Switzerland pubmed.ncbi.nlm.nih.gov

[Cannabis and automobile driving]. [2008]

6. United States pubmed.ncbi.nlm.nih.gov

Medical marijuana and driving: a review. [2022]

7. England pubmed.ncbi.nlm.nih.gov

The effect of cannabidiol on simulated car driving performance: A randomised, double-blind, placebo-controlled, crossover, dose-ranging clinical trial protocol. [2021]

8. United States pubmed.ncbi.nlm.nih.gov

Effect of Cannabidiol and Δ9-Tetrahydrocannabinol on Driving Performance: A Randomized Clinical Trial. [2021]

9. Germany pubmed.ncbi.nlm.nih.gov

Cannabidiol (CBD) content in vaporized cannabis does not prevent tetrahydrocannabinol (THC)-induced impairment of driving and cognition. [2022]

10. England pubmed.ncbi.nlm.nih.gov

Cannabis smoking impairs driving performance on the simulator and real driving: a randomized, double-blind, placebo-controlled, crossover trial. [2019]