Ethanol and Cannabinoid Effects on Simulated Driving and Related Cognition: Sub-Study II (THC-ETOH-II)

April 23, 2026 updated by: Deepak C. D'Souza, Yale University
The overarching goal of this study is to characterize the effects of ethanol and cannabinoids on simulated driving and related cognition.

Study Overview

Status

Active, not recruiting

Conditions

Intervention / Treatment

Detailed Description

To study the effects of oral ethanol (target BAC of ~0.04g/dl; equivalent to consuming approximately 2 drinks over 1 hour) and vaporized cannabis (~450 mg cannabis plant material at a THC concentration of ~1.7%; roughly equivalent to smoking approximately 1/4 of a marijuana cigarette, or "joint") on driving.

Study Type

Interventional

Enrollment (Estimated)

40

Phase

  • Phase 1

Contacts and Locations

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

Study Locations

  • United States
    • Connecticut
      • West Haven, Connecticut, United States, 06516
        • Biological Studies Unit, VA Connecticut Healthcare System

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

21 years to 55 years (Adult)

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Males or females 21 to 55 years of age (extremes included).
  • Occasional current cannabis users.
  • Experience with drinking 2 or more standard drinks of alcohol at least once in lifetime.
  • Able to provide informed consent.

Exclusion Criteria:

  • Cannabis naïve.
  • Alcohol naïve.
  • Positive pregnancy screen
  • Hearing deficits.

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: Crossover Assignment
  • Masking: Quadruple

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Active THC and Placebo Ethanol
Drug: Active inhaled cannabis
~450 mg of active cannabis, which is roughly equivalent to smoking 1/4 of a marijuana cigarette, or "joint". Administered over 20 minutes via a vaporizer.
Drug: Placebo
Approximately 4 drinks of orange juice or ginger ale covered with a trace amount of ethanol on the surface, each administered over approximately 10 minutes.
Drug: Placebo
No active cannabinoids. Administered over 20 minutes via a vaporizer.
Experimental: Active THC and Active Ethanol
Drug: Active inhaled cannabis
~450 mg of active cannabis, which is roughly equivalent to smoking 1/4 of a marijuana cigarette, or "joint". Administered over 20 minutes via a vaporizer.
Drug: Active Oral Ethanol
0.4 g/kg ethanol in orange juice or ginger ale to reach a target BrAC of approximately 0.04%. This dose is equivalent to approximately 2 standard drinks over 1 hour. Approximately 4 drinks, each administered over approximately 10 minutes.
Experimental: Placebo THC and Active Ethanol
Drug: Placebo
Approximately 4 drinks of orange juice or ginger ale covered with a trace amount of ethanol on the surface, each administered over approximately 10 minutes.
Drug: Placebo
No active cannabinoids. Administered over 20 minutes via a vaporizer.
Drug: Active Oral Ethanol
0.4 g/kg ethanol in orange juice or ginger ale to reach a target BrAC of approximately 0.04%. This dose is equivalent to approximately 2 standard drinks over 1 hour. Approximately 4 drinks, each administered over approximately 10 minutes.
Placebo Comparator: Placebo THC and Placebo Ethanol
Drug: Placebo
Approximately 4 drinks of orange juice or ginger ale covered with a trace amount of ethanol on the surface, each administered over approximately 10 minutes.
Drug: Placebo
No active cannabinoids. Administered over 20 minutes via a vaporizer.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Time Frame
Road Tracking Error
Time Frame: baseline, +20, +50, +120, +180 mins after start of alcohol administration
baseline, +20, +50, +120, +180 mins after start of alcohol administration

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Visual Analog Scale (VAS)
Time Frame: baseline, +20, +50, +120, +180, +240 mins after start of alcohol administration
Feeling states associated with alcohol and cannabis intoxication will be measured using this self-report scale of feeling states.
baseline, +20, +50, +120, +180, +240 mins after start of alcohol administration
Willingness to Drive Scale
Time Frame: baseline, +20, +50, +120, +180, +240 mins after start of alcohol administration
Subjects will be asked to rate their willingness to drive at their current state in the context of various scenarios including willingness to drive from testing facility to a number of destinations that are different driving distances.
baseline, +20, +50, +120, +180, +240 mins after start of alcohol administration
Cognitive Test Battery
Time Frame: +40 mins after start of alcohol administration

Several computer tasks will be administered to assess alcohol and THC effects on driving related cognition, including:

visual vigilance, visual motor function, attention and working memory, and processing speed.
+40 mins after start of alcohol administration
Number of Joints Scale
Time Frame: baseline, +20, +50, +120, +180, +240 mins after start of alcohol administration
Subjects will be asked to rate the number of standard joints that they believe they have been administered.
baseline, +20, +50, +120, +180, +240 mins after start of alcohol administration
Number of Drinks Scale
Time Frame: baseline, +20, +50, +120, +180, +240 mins after start of alcohol administration
Subjects will be asked to rate the number of standard drinks that they believe they have been administered.
baseline, +20, +50, +120, +180, +240 mins after start of alcohol administration
Biphasic Alcohol Effects Scale (BAES)
Time Frame: baseline, +20, +50, +120, +180, +240 mins after start of alcohol administration
A scale designed to assess the stimulant and sedative effects associated with alcohol intoxication
baseline, +20, +50, +120, +180, +240 mins after start of alcohol administration

Collaborators and Investigators

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

Sponsor

Yale 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

March 1, 2016

Primary Completion (Estimated)

December 1, 2026

Study Completion (Estimated)

December 1, 2026

Study Registration Dates

First Submitted

March 10, 2016

First Submitted That Met QC Criteria

March 10, 2016

First Posted (Estimated)

March 16, 2016

Study Record Updates

Last Update Posted (Actual)

April 29, 2026

Last Update Submitted That Met QC Criteria

April 23, 2026

Last Verified

April 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 1501015208.B

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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