A Phase 1 interventional study of Medium THC and Placebo THC in Marijuana Impairment, sponsored by Yale University. Completed at 1 site in United States. Open to participants aged 18 Years to 55 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2025-10-09.
Sponsored by Yale University · Phase 1, Interventional, and Other
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.
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.
517 studies on the registry are indexed under Marijuana Abuse; 114 are open to participants now.
This study's enrollment of 41 is below the median of 60 across 421 interventional studies indexed under Marijuana Abuse.
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Exclusion Criteria:
Placebo Marijuana will be administered.
Drug: Placebo THC
Medium THC marijuana will be administered.
Drug: Medium THC
Marijuana flower with medium THC
Marijuana flower with no THC
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.
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.
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.
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.
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.
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.
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.
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.
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.
Time frame: Post placebo at 10 minutes and post active dose administration at 210 minutes.
Plan to share: No
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This study is completed, as verified in Oct 2025. You cannot join it, but the record below documents what was studied.
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Yale University