Effects of THC and Alcohol on Driving Performance

April 20, 2022 updated by: Lakehead University

Determining the Combined Effects of THC and Alcohol on Driving Performance

Low blood concentrations of THC and alcohol appear to have a minimal effect on driving performance.However, there is a gap in the literature about the combined effects of THC and alcohol. There is little empirical evidence to determine whether the combination of THC and alcohol could be additive or multiplicative. This issue is particularly important when dealing with concentrations that are just below legal thresholds - it is important to identify if someone who may have consumed cannabis and alcohol, in quantities that do not exceed legal thresholds, may nonetheless be impaired to drive. Answering this question requires more research on the combined effects of THC and alcohol under tightly controlled experimental conditions. Hence, the purpose of this study is to determine the additive (or multiplicative) effect of standardized low doses of cannabis, in combination with low-doses of alcohol, on a number of outcome measures related to driving. The investigators will focus specifically on the effect of low blood concentrations of THC (0, 125, and 250 µg/kg) alone and in combination with low blood concentrations of alcohol (BAC 0%, .025%, and .049%). They shall determine the combined effect of THC and alcohol on physiological, cognitive, subjective measures of impairment, and simulated driving. This study will focus on younger adults because they have higher impaired driving rates than other age groups. As a secondary aim of the study, the investigators will examine whether previous driving and drug use history are correlated with driving decisions during the simulated drive and subjective measures. This study will contribute to the evidence base informing legislation, policy making, and law enforcement. This study is particularly timely given upcoming changes in legislation about cannabis, and because the combination of THC and alcohol, even below legal thresholds, may lead to impaired driving and crashes.

Study Overview

Status

Withdrawn

Conditions

Intervention / Treatment

Study Type

Interventional

Phase

  • Phase 4

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

Ages Eligible for Study

19 years to 25 years (ADULT)

Accepts Healthy Volunteers

Yes

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • BMI >18 and <30
  • valid G2 or G Ontario driver's license
  • live on-campus or within 15 minutes drive of campus
  • speak fluent English

Exclusion Criteria:

  • history of cardiovascular or psychiatric disorders
  • current use of psychoactive medication
  • current drug or alcohol abuse problem
  • positive drug screen
  • BAC level > .000%

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: RANDOMIZED
  • Interventional Model: FACTORIAL
  • Masking: TRIPLE

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
PLACEBO_COMPARATOR: THC 0 + BAC 0
Participants will receive 0mg of THC in combination with blood alcohol concentrations of .000%.
Drug: THC 0
THC dose = 0mg
Other Names:
  • Cannabis
  • Dronabinol
  • Tetrahydrocannabinol
Other: BAC 0
Blood alcohol concentration = .000%
EXPERIMENTAL: THC 5 + BAC 0
Participants will receive 5mg of THC in combination with blood alcohol concentrations of .000%.
Other: BAC 0
Blood alcohol concentration = .000%
Drug: THC 5
THC dose = 5mg
Other Names:
  • Cannabis
  • Dronabinol
  • Tetrahydrocannabinol
EXPERIMENTAL: THC 10 + BAC 0
Participants will receive 10mg of THC in combination with blood alcohol concentrations of .000%.
Other: BAC 0
Blood alcohol concentration = .000%
Drug: THC 10
THC dose = 10mg
Other Names:
  • Cannabis
  • Dronabinol
  • Tetrahydrocannabinol
EXPERIMENTAL: THC 5 + BAC .025
Participants will receive 5mg of THC in combination with blood alcohol concentrations of .025%.
Drug: THC 5
THC dose = 5mg
Other Names:
  • Cannabis
  • Dronabinol
  • Tetrahydrocannabinol
Other: BAC .025
Blood alcohol concentration = .025%
EXPERIMENTAL: THC 10 + BAC .025
Participants will receive 125 µg/kg of THC in combination with blood alcohol concentrations of .025%.
Drug: THC 5
THC dose = 5mg
Other Names:
  • Cannabis
  • Dronabinol
  • Tetrahydrocannabinol
Other: BAC .025
Blood alcohol concentration = .025%
EXPERIMENTAL: THC 0 + BAC .049
Participants will receive 0 µg/kg of THC in combination with blood alcohol concentrations of .049%.
Drug: THC 0
THC dose = 0mg
Other Names:
  • Cannabis
  • Dronabinol
  • Tetrahydrocannabinol
Drug: THC 10
THC dose = 10mg
Other Names:
  • Cannabis
  • Dronabinol
  • Tetrahydrocannabinol
Other: BAC .025
Blood alcohol concentration = .025%
Other: BAC .049
Blood alcohol concentration = .049%
EXPERIMENTAL: THC 5 + BAC .049
Participants will receive 5mg of THC in combination with blood alcohol concentrations of .049%.
Drug: THC 5
THC dose = 5mg
Other Names:
  • Cannabis
  • Dronabinol
  • Tetrahydrocannabinol
Other: BAC .049
Blood alcohol concentration = .049%
EXPERIMENTAL: THC 10 + BAC .049
Participants will receive 10mg of THC in combination with blood alcohol concentrations of .049%.
Drug: THC 5
THC dose = 5mg
Other Names:
  • Cannabis
  • Dronabinol
  • Tetrahydrocannabinol
Other: BAC .049
Blood alcohol concentration = .049%
EXPERIMENTAL: THC 0 + BAC .025
Participants will receive 0 µg/kg of THC in combination with blood alcohol concentrations of .025%.
Drug: THC 0
THC dose = 0mg
Other Names:
  • Cannabis
  • Dronabinol
  • Tetrahydrocannabinol
Drug: THC 10
THC dose = 10mg
Other Names:
  • Cannabis
  • Dronabinol
  • Tetrahydrocannabinol
Other: BAC .025
Blood alcohol concentration = .025%
Other: BAC .049
Blood alcohol concentration = .049%

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Demerit Points on Simulated Road Test
Time Frame: @2.5 hours
Demerit points incurred for driving errors during a simulated a G2 exit exam (the final step in Ontario's graduated licensing framework) on a STISIM Drive 3-screen driving simulator; demerit points will be assigned in real-time by a member of the research team based on the Ontario Ministry of Transportation scoring scheme
@2.5 hours

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Standard Deviation of Lane Position in Meters (STISIM Drive-Recorded Variable)
Time Frame: @2.5 hours
Recorded by the STISIM simulator during the simulation
@2.5 hours
Mean and Standard Deviation of Velocity in Meters/Second (STISIM Drive-Recorded Variable)
Time Frame: @2.5 hours
Recorded by the STISIM simulator during the simulation
@2.5 hours
Mean and Standard Deviation of Acceleration in Meters/Second (STISIM Drive-Recorded Variable)
Time Frame: @2.5 hours
Recorded by the STISIM simulator during the simulation
@2.5 hours
Blood Pressure (Systolic/Diastolic mmHg)
Time Frame: @25 minutes and 2 hours
Systolic & diastolic blood pressure via automated blood pressure cuff
@25 minutes and 2 hours
Heart Rate (BPM) & Heart Rate Variability via ECG
Time Frame: Hour 0-3.5
Continuous heart rate in beats per minute via 3-lead electrocardiography recording; will allow for calculation of heart rate variability)
Hour 0-3.5
Electrical Brain Activity via EEG
Time Frame: Hour 0-3.5
Continuous brain activity via electroencephalography recording
Hour 0-3.5
Median Response Time and Efficiency in Alerting, Orienting & Executive Attention as Measured by the Attention Network Test (in milliseconds)
Time Frame: @25 minutes and 2 hours
A computerized test to measure participants' performance in three separate components of attention: alerting, orienting, and executive attention
@25 minutes and 2 hours
Perceptual Motor Speed & Efficiency as Measured by Time (in seconds) to Complete Trail Making Tests A&B
Time Frame: @25 minutes and 2 hours
A pen and paper test to measure perceptual motor speed and efficiency
@25 minutes and 2 hours
Visual Analogue Scale of Perceived Effects
Time Frame: @25 minutes and 2 hours
Ratings of participants' current perceptions of mood and bodily sensations (22 items including anxiety, alertness, dizziness, dry mouth) driving (3 items related to current willingness to drive), and subjective impairment (at time 2 only; 6 items related to strength of effects, perceived performance on tests); all items measures from not at all>extremely or absent>severe on a 100 mm line
@25 minutes and 2 hours

Collaborators and Investigators

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

Sponsor

Lakehead University

Investigators

  • Principal Investigator: Michel Bédard, PhD, Lakehead University

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 (ANTICIPATED)

July 1, 2021

Primary Completion (ANTICIPATED)

December 1, 2021

Study Completion (ANTICIPATED)

December 1, 2021

Study Registration Dates

First Submitted

May 18, 2018

First Submitted That Met QC Criteria

June 1, 2018

First Posted (ACTUAL)

June 14, 2018

Study Record Updates

Last Update Posted (ACTUAL)

April 25, 2022

Last Update Submitted That Met QC Criteria

April 20, 2022

Last Verified

April 1, 2022

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 2018502

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

Yes

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

Yes

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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