Marijuana ImpairmentPhase 1NHTSA-IINCT05115513
Standardized Field Test for Marijuana Impairment II
A Phase 1 study testing Medium THC in people with Marijuana Impairment, run by Yale University at 1 site in United States.
Trial summary
This research responds to NHTSA's request with a proposal to increase our understanding of smoked cannabis' (CNB's) acute effects on driving-relevant cognition and simulated driving performance, the persistence of these deficits over the hours after use, and the influence of prior experience with CNB on these effects. Read more about this study
- Who is it for?
- Ages 18 to 55 yearsHealthy volunteers can take part
- Conditions the study is for
- Marijuana Impairment
- What is being tested?
- Medium THC
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 41 participants
- Where
- 1 siteUnited States
- Study dates
- 25 Aug 2022to 21 Aug 2023
- Phase
- Phase 1
- Are there results?
- None posted in the registry
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 18 to 55 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- 18-55 yrs/ old
- Current driver's license and history of repeated highway vehicle driving experience (at least 2 years)
- Recent, recurrent CNB use and felt high when used
- Able to read, speak, and understand English
- Able and willing to provide written informed consent, and willing to commit to the study protocol
Who cannot join
- Current marijuana tolerance, desire to cut down, or cravings to use during periods of abstinence
- New CNB users who have not used at least once during their lifetime.
- Positive screen for drug and alcohol (except THC) on test day will result in rescheduling the appointment
- Former CNB users who are abstaining
- Pregnancy, breastfeeding, and ineffective birth control methods.
- History of adverse psychological or medical effects following cannabis use
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- serious medical, neuro-ophthalmological, or neurological illness (i.e. cancer, seizure disorders, encephalopathy)
- History of head trauma with loss of consciousness > 30 minutes or concussion lasting 30 days.
- IQ <80 on the Wechsler Abbreviated Scale of Intelligence
- Inability to comprehend written instructions using the WRAT 4 reading achievement test
- Any medical/neurological condition that could compromise neurocognitive performance (i.e. epilepsy, multiple sclerosis, fetal alcohol syndrome)
- Uncontrolled, persistent high blood pressure
- Anyone deemed unsafe to study personnel for any reason
Trial locations and contacts
1 site in 1 country.
United States1 site
Olin Neuropsychiatry Research Center
Hartford, Connecticut, 06106
About this study
Official title: Examine the Feasibility of a Standardized Field Test for Marijuana Impairment: Laboratory Evaluations II
This research responds to NHTSA's request with a proposal to increase our understanding of smoked cannabis' (CNB's) acute effects on driving-relevant cognition and simulated driving performance, the persistence of these deficits over the hours after use, and the influence of prior experience with CNB on these effects. This extension study will aim to further investigate marijuana impaired behavior, using a similar design to our previous NHTSA Examine the Feasibility of a Standardized Field Test for Marijuana Impairment and the prior NIDA Neuroscience of Marijuana-Impaired Driving award, that used similar techniques and measures to quantify marijuana impaired automobile driving. We will be utilizing tasks and assessments that were shown to be strong indicators for cognitive and driving impairment in our NHTSA study.
Read the detailed description
The proposed study was based upon a careful and thorough review of the scientific literature describing CNB effects on cognitive test performance and driving, as well as current state-of-knowledge on the sensitivity of biological assays for identifying recent CNB use. The study will carefully characterize the persistence of CNB's acute effects on cognitive test performance and driving over a several-hour time span. This will allow us to identify the point at which any effects of CNB intoxication driving-related cognitive tests, and driving performance cannot be distinguished from normal, i.e., the first step towards establishing standards for legal and social policy. The data obtained from simulated driving, cognitive tests, and biological assays of THC will be used in analyses aimed at identifying what tests or combination of tests predict both recent use and driving impairment risk.
This study will consist of 2 days (screening visit and dose visit). In a non-randomized, single blinded study, we will dose participants with placebo and high THC marijuana, about an hour apart, using paced inhalation through a vaporizer, an efficient means of delivering a standard THC dose. Participants will be told that the order they receive the doses will be random but they will always receive the placebo first, followed by the high dose. This will allow for standardization across all subjects and comparative values between placebo and drug. After inhaling the placebo dose, participants will be asked to complete one round of cognitive testing and a shortened version of the driving simulator (10 mins vs 30 mins). Approximately one hour post placebo dose, subjects will be administered high THC marijuana. Following this dosing, we will assess impairment through cognitive testing as well as a simulated driving test and neuropsychological tests. Samples of blood will also be collected at multiple time points throughout the study visits to be measured for THC concentration and its metabolites. This allows clarification between the relationship of impairment, as well as subjective and objective intoxication, and levels of THC and it's metabolites in the users system.
- Conditions
- Marijuana Impairment
- Being tested
- Medium THC, Placebo THC
- Keywords
- Marijuana, THC, Cannabis, Driving, Impairment, Intoxication
- Medical subject headings
- Marijuana Abuse
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Medium THCDrug
Marijuana flower with medium THC
Placebo THCDrug
Marijuana flower with no THC
| Study group | Role | What they receive |
|---|---|---|
| Placebo Marijuana | Experimental | Placebo Marijuana will be administered. Receives: Drug: Placebo THC |
| Medium THC Marijuana | Experimental | Medium THC marijuana will be administered. Receives: Drug: Medium THC |
What is being measured
The primary outcome is the main question the study is designed to answer.
Marijuana induced performance changes on Cogstate Groton Maze Learning task.
The Cogstate Groton Maze Learning task assesses spatial learning and memory, it will be administered prior to dosing and at various time points after dosing.
Measured: Post placebo at 30 minutes and post active dose administration at: 30 minutes, 60 minutes , 90 minutes, 120 minutes, 150 minutes, 180 minutes.
Marijuana induced performance changes on Inquisit Maze Learning task.
The Inquisit Maze Learning task assesses spatial learning and memory, it will be administered prior to dosing and at various time points after dosing.
Measured: Post placebo at 30 minutes and post active dose administration at: 30 minutes, 60 minutes , 90 minutes, 120 minutes, 150 minutes, 180 minutes.
Marijuana induced performance changes on the Time Reproduction Task.
The Time Reproduction Task assesses general motor coordination plus timing, it will be administered prior to dosing and at various time points after dosing.
Measured: Post placebo at 30 minutes and post active dose administration at: 30 minutes, 60 minutes , 90 minutes, 120 minutes, 150 minutes, 180 minutes.
Secondary outcomes (2)
Change in concentration of THC/metabolites in blood samples.
Blood samples with be collected at 5 times throughout each day to assess for changes of THC and its metabolite levels.
Measured: Post placebo at 5 minutes and post active dose administration at: 30 minutes, 60 minutes , 90 minutes, 120 minutes, 150 minutes, 180 minutes.
Change in performance on simulated driving Road Tracking Task.
The Road Tracking Task measures operational control of the vehicle. Operational control is measured by standard deviation of lane position from the center point of the lane.
Measured: Post placebo at 10 minutes and post active dose administration at 210 minutes.
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted10 Nov 2021
- Study start25 Aug 2022
- Primary completion21 Aug 2023
- Study completion21 Aug 2023
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Marijuana ImpairmentStudies of the same condition, open and under way.
- More trials run by Yale UniversityThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
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 1
- Primary purpose
- Other
- Allocation
- Non-randomised
- Intervention model
- Crossover
- Masking
- Single blind
- Who is masked
- Participant
- Enrolment
- 41 participants (actual)
Sponsor and investigators
- Lead sponsor
- Yale University
- Sponsor type
- University, hospital or other
- Collaborators
- National Highway Traffic Safety Administration (NHTSA), Hartford Hospital, National Institute on Drug Abuse (NIDA)
- Responsible party
- Principal investigator, Godfrey Pearlson, Yale University
- Investigators
- Godfrey Pearlson, M.D, Principal investigator, Yale University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05115513
- Sponsor's protocol ID
- HHC-2021-0333
- Other IDs
- DTNH2216C00022, 2000032628
- Acronym
- NHTSA-II
- Status last verified
- Oct 2025
- First submitted
- 29 Oct 2021
- Last updated
- 9 Oct 2025
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 9 Oct 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Examine the Feasibility of a Standardized Field Test for Marijuana Impairment: Laboratory Evaluations II
- ClinicalTrials.gov ID
- NCT05115513
- Acronym / sponsor ID
- NHTSA-II / HHC-2021-0333
- Conditions
- Marijuana Impairment
- Keywords
- Marijuana, THC, Cannabis, Driving, Impairment, Intoxication
- Phase
- Phase 1
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 41 participants (actual)
- Lead sponsor
- Yale UniversityUniversity, hospital or other
- Collaborators
- National Highway Traffic Safety Administration (NHTSA), Hartford Hospital, National Institute on Drug Abuse (NIDA)
- Study start
- 25 Aug 2022 (actual)
- Primary completion
- 21 Aug 2023 (actual)
- Study completion
- 21 Aug 2023 (actual)
- First posted
- 10 Nov 2021 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This research responds to NHTSA's request with a proposal to increase our understanding of smoked cannabis' (CNB's) acute effects on driving-relevant cognition and simulated driving performance, the persistence of these deficits over the hours after use, and the influence of prior experience with CNB on these effects. This extension study will aim to further investigate marijuana impaired behavior, using a similar design to our previous NHTSA Examine the Feasibility of a Standardized Field Test for Marijuana Impairment and the prior NIDA Neuroscience of Marijuana-Impaired Driving award, that used similar techniques and measures to quantify marijuana impaired automobile driving. We will be utilizing tasks and assessments that were shown to be strong indicators for cognitive and driving impairment in our NHTSA study.
Detailed description
The proposed study was based upon a careful and thorough review of the scientific literature describing CNB effects on cognitive test performance and driving, as well as current state-of-knowledge on the sensitivity of biological assays for identifying recent CNB use. The study will carefully characterize the persistence of CNB's acute effects on cognitive test performance and driving over a several-hour time span. This will allow us to identify the point at which any effects of CNB intoxication driving-related cognitive tests, and driving performance cannot be distinguished from normal, i.e., the first step towards establishing standards for legal and social policy. The data obtained from simulated driving, cognitive tests, and biological assays of THC will be used in analyses aimed at identifying what tests or combination of tests predict both recent use and driving impairment risk.
This study will consist of 2 days (screening visit and dose visit). In a non-randomized, single blinded study, we will dose participants with placebo and high THC marijuana, about an hour apart, using paced inhalation through a vaporizer, an efficient means of delivering a standard THC dose. Participants will be told that the order they receive the doses will be random but they will always receive the placebo first, followed by the high dose. This will allow for standardization across all subjects and comparative values between placebo and drug. After inhaling the placebo dose, participants will be asked to complete one round of cognitive testing and a shortened version of the driving simulator (10 mins vs 30 mins). Approximately one hour post placebo dose, subjects will be administered high THC marijuana. Following this dosing, we will assess impairment through cognitive testing as well as a simulated driving test and neuropsychological tests. Samples of blood will also be collected at multiple time points throughout the study visits to be measured for THC concentration and its metabolites. This allows clarification between the relationship of impairment, as well as subjective and objective intoxication, and levels of THC and it's metabolites in the users system.
Study design
- Primary purpose
- Other
- Allocation
- Non-randomised
- Intervention model
- Crossover
- Masking
- Single blind (participant)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Placebo Marijuana | Experimental | Drug: Placebo THCPlacebo Marijuana will be administered. |
| Medium THC Marijuana | Experimental | Drug: Medium THCMedium THC marijuana will be administered. |
Who may qualify
- Ages
- 18 to 55 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (5 listed)
- 18-55 yrs/ old
- Current driver's license and history of repeated highway vehicle driving experience (at least 2 years)
- Recent, recurrent CNB use and felt high when used
- Able to read, speak, and understand English
- Able and willing to provide written informed consent, and willing to commit to the study protocol
Key exclusion criteria (13 listed)
- Current marijuana tolerance, desire to cut down, or cravings to use during periods of abstinence
- New CNB users who have not used at least once during their lifetime.
- Positive screen for drug and alcohol (except THC) on test day will result in rescheduling the appointment
- Former CNB users who are abstaining
- Pregnancy, breastfeeding, and ineffective birth control methods.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Medium THCMarijuana flower with medium THC | Drug | Medium THC Marijuana |
| Placebo THCMarijuana flower with no THC | Drug | Placebo Marijuana |
Primary outcome
Marijuana induced performance changes on Cogstate Groton Maze Learning task.
Time frame: Post placebo at 30 minutes and post active dose administration at: 30 minutes, 60 minutes , 90 minutes, 120 minutes, 150 minutes, 180 minutes.
The Cogstate Groton Maze Learning task assesses spatial learning and memory, it will be administered prior to dosing and at various time points after dosing.
Marijuana induced performance changes on Inquisit Maze Learning task.
Time frame: Post placebo at 30 minutes and post active dose administration at: 30 minutes, 60 minutes , 90 minutes, 120 minutes, 150 minutes, 180 minutes.
The Inquisit Maze Learning task assesses spatial learning and memory, it will be administered prior to dosing and at various time points after dosing.
Marijuana induced performance changes on the Time Reproduction Task.
Time frame: Post placebo at 30 minutes and post active dose administration at: 30 minutes, 60 minutes , 90 minutes, 120 minutes, 150 minutes, 180 minutes.
The Time Reproduction Task assesses general motor coordination plus timing, it will be administered prior to dosing and at various time points after dosing.
2 secondary outcomes
Change in concentration of THC/metabolites in blood samples.
Time frame: Post placebo at 5 minutes and post active dose administration at: 30 minutes, 60 minutes , 90 minutes, 120 minutes, 150 minutes, 180 minutes.
Change in performance on simulated driving Road Tracking Task.
Time frame: Post placebo at 10 minutes and post active dose administration at 210 minutes.
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 9 Oct 2025.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Godfrey Pearlson, M.D principal investigator
Yale University
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 1 study testing Medium THC in people with Marijuana Impairment, run by Yale University at 1 site in United States.
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 5 inclusion and 13 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: finished, as of the sponsor's last update on 9 Oct 2025. 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 United States. 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.
What does this phase mean?
Phase 1 studies test a treatment in a small group of people for the first time or in a new way, mainly to check safety and find the right dose.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Marijuana induced performance changes on Cogstate Groton Maze Learning task. (time frame: Post placebo at 30 minutes and post active dose administration at: 30 minutes, 60 minutes , 90 minutes, 120 minutes, 150 minutes, 180 minutes.). 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?
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 9 Oct 2025.