Marijuana and Alcohol Effects on Driving Impairment

(Alc-NHTSA Trial)

Overseen By Suyash Adhikari, B.S

Age: 18 - 65

Sex: Any

Trial Phase: Phase < 1

Sponsor: Yale University

Disqualifiers: Pregnancy, Psychiatric disorders, Neurological illness, others

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

Compensation: Varies

Number of Visits: 5

Duration: 4 days

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial examines how marijuana and alcohol together affect driving safety. Researchers will use a driving simulator to assess the impact of different doses of THC (the active component of marijuana) and alcohol. Participants will receive either a low or high dose of THC with a set amount of alcohol, or just alcohol without THC. Individuals who have used cannabis for at least two years, regularly drink and smoke, and hold a driver's license with recent highway experience may be suitable for this trial. As an Early Phase 1 trial, the study aims to understand the initial effects of combining THC and alcohol on driving, offering participants a chance to contribute to groundbreaking research.

Will I have to stop taking my current medications?

The trial information does not specify if you need to stop taking your current medications. However, if you have a severe substance use disorder (except for cannabis and tobacco) or certain medical conditions, you may not be eligible to participate.

Is there any evidence suggesting that this trial's treatments are likely to be safe?

Research shows that mixing THC (the active ingredient in marijuana) with alcohol can impair driving ability. At low doses of THC with alcohol, studies find that marijuana users might drive more cautiously, such as by reducing speed. However, even this combination can still impair driving, especially at night.

With higher doses of THC and alcohol, the effects become more pronounced. Research indicates that reaction times significantly slow, causing drivers to take longer to respond to road conditions. This combination also leads drivers to maintain greater distances between cars and drive at lower speeds.

In both cases, while the impairments might seem minor, they can still increase the risk of accidents. These findings are crucial for understanding how these substances might affect safety, particularly when driving. ^{1 2 3 4 5}

Why are researchers excited about this trial?

Researchers are excited about this trial because it explores how different doses of THC, combined with alcohol, impact driving impairment. Unlike typical studies that look at alcohol or cannabis effects separately, this trial investigates the combined impact, which is more reflective of real-world scenarios. By including various combinations, such as low and high THC doses with alcohol, and comparing them to placebo groups, the trial aims to provide valuable insights into how these substances might impair driving abilities differently. This could lead to better-informed guidelines and safety measures for drivers who use these substances.

What evidence suggests that this trial's treatments could be effective for assessing driving impairment?

This trial will compare the effects of different combinations of THC and alcohol on driving impairment. Participants in one arm will receive a low dose of THC with alcohol, resulting in a BAC of 0.05, while another arm will involve a high dose of THC with the same BAC level. Additionally, some arms will administer a placebo drug with no THC, combined with alcohol at BAC levels of 0.05 and 0.08. Research has shown that using both low and high amounts of THC with alcohol can make driving unsafe. Studies find that driving is more affected when both THC and alcohol are used together than when either is used alone. Even small amounts of THC with alcohol can noticeably impair driving in tests. Higher amounts of THC with alcohol cause even more impairment, indicating a stronger effect on driving skills. These findings emphasize that THC, especially when mixed with alcohol, can greatly affect safe driving. ^{1 6 7 8 9}

Who Is on the Research Team?

Godfrey Pearlson, M.D

Principal Investigator

Founding Director, Olin Neuropsychiatry Center; Yale University

Are You a Good Fit for This Trial?

This trial is for adults who regularly drink alcohol and smoke marijuana, with at least 2 years of cannabis use and driving experience. They must not be novice users, should have used cannabis at least five times in their life without withdrawal symptoms, and hold a valid driver's license.

Inclusion Criteria

You regularly smoke and drink alcohol.

I have used cannabis regularly for the past 2 years and experience its effects.

I have a driver's license and 2 years of recent highway driving experience.

Exclusion Criteria

I have had a head injury with unconsciousness for over 30 minutes or a concussion that lasted 30 days.

I do not have conditions like epilepsy that affect my brain function.

You have been diagnosed with a mental health condition according to the DSM-5.

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

1 day

1 visit (in-person)

Treatment

Participants receive alcohol and marijuana doses followed by cognitive and simulated driving tests

4 days

4 visits (in-person)

Follow-up

Participants are monitored for safety and effectiveness after treatment

2 weeks

What Are the Treatments Tested in This Trial?

Interventions

• Laboratory Evaluations
• Standardized Field Test for Marijuana and Alcohol Impairment

Trial Overview The study tests the effects of different levels of marijuana (high to low) and alcohol (0.08 BAC to placebo) on simulated driving performance. It aims to understand how these substances combined can impair driving abilities.

How Is the Trial Designed?

Group I: Placebo Drug + 0.08 BAC Alc Experimental Treatment 2 Interventions

Participants will receive placebo drug with no THC along with alcohol leading to a BAC of 0.08.

Group II: Placebo Drug + 0.05 BAC Alc Experimental Treatment 2 Interventions

Participants will receive placebo drug with no THC along with alcohol leading to a BAC of 0.05.

Group III: Low Dose THC + 0.05 BAC Alc Experimental Treatment 2 Interventions

Participants will receive low dose of THC along with alcohol leading to a BAC of 0.05.

Group IV: High Dose THC + 0.05 BAC Alc Experimental Treatment 2 Interventions

Participants will receive high dose of THC along with alcohol leading to a BAC of 0.05.

Who Is Running the Clinical Trial?

Yale University

Lead Sponsor

Trials

1,963

Recruited

3,046,000+

National Highway Traffic Safety Administration

Collaborator

Trials

2

Recruited

40+

National Highway Traffic Safety Administration (NHTSA)

Collaborator

Trials

8

Recruited

940+

Hartford Hospital

Collaborator

Trials

140

Recruited

19,700+

National Institute on Drug Abuse (NIDA)

Collaborator

Trials

2,658

Recruited

3,409,000+

Citations

1. pubmed.ncbi.nlm.nih.gov pubmed.ncbi.nlm.nih.gov/22871272/

The effects of cannabis and alcohol on simulated driving Results: Driving simulator performance was more impaired in the THC and alcohol combined conditions. Consistent with past research, the level of THC detected in ...

2. sciencedirect.com sciencedirect.com/science/article/abs/pii/S0001457510001429

The effect of alcohol, THC and their combination on ... Overall, the combination of alcohol and THC had the most intense effect after intake. This effect was reflected in performance impairments observed in the ...

3. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC2722956/

THE EFFECT OF CANNABIS COMPARED WITH ... In summary, laboratory tests and driving studies show that cannabis may acutely impair several driving-related skills in a dose-related fashion, but that the ...

4. sciencedirect.com sciencedirect.com/science/article/abs/pii/S0001457512002709

The effects of cannabis and alcohol on simulated driving Driving simulator performance was more impaired in the THC and alcohol combined conditions. Consistent with past research, the level of THC detected in blood is ...

5. wtsc.wa.gov wtsc.wa.gov/wp-content/uploads/dlm_uploads/2018/05/Marijuana-and-Alcohol-Involvement-in-Fatal-Crashes-in-WA_FINAL.pdf

Marijuana Use, Alcohol Use, and Driving in Washington State ... BAC of 0.05 or higher, and 14.1 times more likely to have combined THC with alcohol. Compton (2017). Marijuana-Impaired Driving – A Report to Congress. U.S. ...

6. sciencedirect.com sciencedirect.com/science/article/abs/pii/S0379073814005350

The combined effects of alcohol and cannabis on driving Driving under the influence of alcohol or cannabis alone is associated with increased crash risk. This study explores the combined influence of low levels ...

7. nhtsa.gov nhtsa.gov/sites/nhtsa.gov/files/documents/812440-marijuana-impaired-driving-report-to-congress.pdf

Marijuana-Impaired Driving – A Report to Congress Subjects dosed on marijuana showed reduced mean speeds, increased time driving below the speed limit and increased following distance during a car following ...

8. aafp.org aafp.org/pubs/afp/issues/2000/1001/p1652.html

Driving Impairment from Marijuana and Alcohol The mean reaction time increased from 4.65 seconds at baseline to 6.33 seconds when drivers were under the influence of alcohol and marijuana.

9. cdc.gov cdc.gov/mmwr/volumes/68/wr/mm6850a1.htm

Driving Under the Influence of Marijuana and Illicit Drugs .. ... Research has determined that co-use of marijuana or illicit drugs with alcohol increases the risk for driving impairment (5,6). The use of ...