The Impact and Detection of Driving Impairments Associated With Acute Cannabis Smoking

Sponsor
University of California, San Diego (Other)
Overall Status
Completed
CT.gov ID
NCT02849587
Collaborator
(none)
199
1
3
27.7
7.2

Study Details

Study Description

Brief Summary

This study was authorized by the California Legislature (Assembly Bill 266, the Medical Marijuana Regulation and Safety Act to help with detection of driving under the influence of cannabis. One hundred and eighty healthy volunteers will inhale smoked cannabis with either 0% (placebo), 5.9%, or 13.4% Δ9-tetrahydrocannabinol (THC) at the beginning of the day, and then complete driving simulations, iPad-based performance assessments, and bodily fluid draws (e.g., blood, saliva, breath) before the cannabis smoking and a number of times over the subsequent 6 hours after cannabis smoking. The purpose is to determine (1) the relationship of the dose of Δ9-THC on driving performance and (2) the duration of driving impairment in terms of hours from initial use, (3) if saliva or expired air can serve as a useful substitute for blood sampling of Δ9-THC, and (4) if testing using an iPad can serve as a useful adjunct to the standardized field sobriety test in identifying acute impairment from cannabis.

Condition or Disease Intervention/Treatment Phase
Phase 1/Phase 2

Detailed Description

There are several studies that suggest higher doses of whole-blood Δ9-tetrahydrocannabinol (Δ9-THC) concentration are associated with increased crash risk and crash culpability. However, attempts to define a cut-off point for blood Δ9-THC levels have proven to be challenging. Unlike alcohol, for which a level can be reasonably measured using a breathalyzer (and confirmed with a blood test), detection of a cut-off point for intoxication related to Δ9-THC concentration has eluded scientific verification. Recent evidence suggests blood Δ9-THC concentrations of 2-5 ng/mL are associated with substantial driving impairment, particularly in occasional smokers. Others have countered that this level leads to false positives, particularly in heavy cannabis users inasmuch as THC may be detectable in their blood specimens for 12-24 hours after inhalation. Given that 12 to 24 hours is beyond the likely period of driving impairment, this would appear to be a justifiable objection to a per se cut-off point for a Δ9-THC concentration indicative of impairment. Maximal driving impairment is found 20 to 40 minutes after smoking, and the risk of driving impairment decreases over the following hours, at least in those who smoke 18 mg Δ9-THC or less, the dose often used experimentally to duplicate a single joint. Other studies, however, report residual motor vehicle accident crash risk when cannabis is used within 4 hours prior to driving.

The roadside examination using the Standardized Field Sobriety Test (SFST) for proof of cannabis-related impairment has not been an ideal alternative to blood levels. Originally devised to evaluate impairment under the influence of alcohol, the SFST is comprised of three examinations administered in a standardized manner by law enforcement officers. The 'Horizontal Gaze Nystagmus' (HGN), the 'One Leg Stand' (OLS) and the 'Walk and Turn' test (WAT) require a person to follow instructions and perform motor activities. During the assessments, officers observe and record signs of impairment. In one study, Δ9-THC produced impairments on overall SFST performance in 50 % of the participants. In a separate study involving acute administration of cannabis, 30% of people failed the SFST. This discrepancy was thought to be in part due to the participant's cannabis use history, as well as low percentage of THC in the cannabis. The reported frequency of cannabis use varied from once a week to once every 2-6 months in the study where there was a failure on the SFST by 50% of the participants. The other study included more frequent users who smoked cannabis on at least four occasions per week.

Based upon the above, another means is needed to help law enforcement officers discern driving under the influence of cannabis. One future possibility is the development of performance-based measures of cannabis-related impairments. This will include testing of critical tracking, time estimation, balance and visual spatial learning. The investigators have selected brief measures in order to be practicably administered repeatedly over a short time period, as well as tests that have the potential to translate to a field-feasible tablet-based format, should there be benefit in possibly including these in future performance-based measures for use in the field by law enforcement officers (e.g., a cannabis-focused field sobriety test).

Study Design

Study Type:
Interventional
Actual Enrollment :
199 participants
Allocation:
Randomized
Intervention Model:
Parallel Assignment
Intervention Model Description:
Participants will be randomized to smoke a cannabis cigarette containing placebo (.02%), 5.9% or 13.4% THC.Participants will be randomized to smoke a cannabis cigarette containing placebo (.02%), 5.9% or 13.4% THC.
Masking:
Triple (Participant, Investigator, Outcomes Assessor)
Masking Description:
Product will be dispensed from the Research Pharmacy. All assessors, investigators, and participants are blinded to the THC content.
Primary Purpose:
Screening
Official Title:
A Randomized, Controlled Trial of Cannabis in Healthy Volunteers Evaluating Simulated Driving, Field Performance Tests and Cannabinoid Levels
Actual Study Start Date :
Feb 24, 2017
Actual Primary Completion Date :
Jun 17, 2019
Actual Study Completion Date :
Jun 17, 2019

Arms and Interventions

Arm Intervention/Treatment
Placebo Comparator: Placebo Cannabis

Subjects will smoke cannabis with placebo THC (.02%) ad libitum

Drug: Cannabis
Participants will smoke a cannabis cigarette ad libitum as per their usual routine
Other Names:
  • Marijuana
  • Experimental: Cannabis with 5.9% THC

    Subjects will smoke cannabis cigarettes with 5.9% THC ad libitum

    Drug: Cannabis
    Participants will smoke a cannabis cigarette ad libitum as per their usual routine
    Other Names:
  • Marijuana
  • Experimental: Cannabis with 13.4% THC

    Subjects will smoke cannabis cigarettes with 13.4% THC ad libitum

    Drug: Cannabis
    Participants will smoke a cannabis cigarette ad libitum as per their usual routine
    Other Names:
  • Marijuana
  • Outcome Measures

    Primary Outcome Measures

    1. Change in Composite Drive Score (CDS) From Pre-smoking Simulation [Participants are assessed pre-smoking, and then approximately 30m, 1h 30m, 3h 30m and 4h 30m post-smoking]

      The Composite Drive Score (CDS) is a z-score comprised of key variables from the simulator tasks (SDLP, speed deviation, and task accuracy during the modified Surrogate Reference Task (mSuRT); coherence from the car following task). This outcome reflects the change in CDS from the pre-smoking assessment, at each timepoint. The z-score indicates the number of standard deviations away from the mean from the baseline performance for the entire group (n = 191). A Z-score of 0 is equal to the mean of a reference population (in this case the pre-smoking performance for the entire group). Higher z-scores at each timepoint indicate worse performance (variables that went in the opposite direction were reflected in order to have all variables have the same direction). When examining the change in Composite Drive Score (this outcome variable), a higher score indicates a decline in performance (e.g., Time 2 minus Time 1).

    Secondary Outcome Measures

    1. Simulator: Standard Deviation of Lateral Position (SDLP) [Participants are assessed pre-smoking, and then approximately 30m, 1h 30m, 3h 30m and 4h 30m post-smoking]

      This measures the standard deviation of lateral (lane) position, or the degree to which the participant "swerves" within the road lane on the driving simulation during the modified Surrogate Reference Task (mSuRT). The range is from .39 to 3.33. A higher score indicates worse performance.

    2. Simulator: Speed Deviation [Participants are assessed pre-smoking, and then approximately 30m, 1h 30m, 3h 30m and 4h 30m post-smoking]

      The variability in speed during the modified Surrogate Reference Test (mSuRT). The speed is in miles per hour. Range is from .17 to 12.85. A higher score indicates worse performance.

    3. Simulator: Correct Hits on mSuRT [Participants are assessed pre-smoking, and then approximately 30m, 1h 30m, 3h 30m and 4h 30m post-smoking]

      The number of times the participant touched the correct stimulus (circle) on the iPad, during modified Surrogate Reference Task (mSuRT). Range is from 8 to 32. A higher score is a better score.

    4. Simulator: Car Following - Coherence [Participants are assessed pre-smoking, and then approximately 30m, 1h 30m, 3h 30m and 4h 30m post-smoking]

      Coherence is the correlation (0 to 1) between the participant and the lead car (which speeds up and slows down), representing the participant's ability to accurately speed up and slow down similarly to the lead car. Range of scores is from .01 to .97. A higher score is a better score.

    5. Simulator: Response Delay - Car Following [Participants are assessed pre-smoking, and then approximately 30m, 1h 30m, 3h 30m and 4h 30m post-smoking]

      Time delay (in seconds) in responding to changes in the lead car's speed. Range is from -5.8 to 6.0. A higher score indicates a worse score.

    6. Simulator: Distance From Lead Car - Car Following [Participants are assessed pre-smoking, and then approximately 30m, 1h 30m, 3h 30m and 4h 30m post-smoking]

      The outcome is distance from the lead car (in virtual feet) during the Car Following Task

    7. Tablet Assessment: Dual Attention Missed Switches [Participants assessed pre-smoking and 1 hour, 2 hours, 4 hours, and 5 hours after smoking]

      The participant follows a moving target (square) with her/his finger, and switches to following a new stimulus when it appears in the corner of the screen. Each participant was classified as to whether he/she missed any of these switches during the trial. The outcome is the proportion of participants within each group who missed at least one switch. The range is from 0 to 1. Higher indicates a worse score.

    8. Tablet Assessment: Lane Tracking Standard Deviation [Participants assessed pre-smoking and 1 hour, 2 hours, 4 hours, and 5 hours after smoking]

      The participant is to rotate the iPad in order to keep a round object in the center, between two lines (lanes). This measure is the standard deviation of the position of the round object during the task (in essence, how much "swerving" there is within the lane). The range is from 8.2 to 189.4. A higher score indicates worse performance.

    9. Tablet Assessment: Visual Spatial Learning Test Number Correct [Participants assessed pre-smoking and 1 hour, 2 hours, 4 hours, and 5 hours after smoking]

      Assessment of short-term memory for abstract figures. The participant is to memorize abstract figures and their locations on a 3 x 3 grid. After initial viewing (10 seconds), the figures go away for either 4, 12, or 24 seconds. The participant is then to identify which figures were in the initial viewing (from a list at the bottom of the screen), and place them at the correct location. This is the number of correctly identified figures. The range is from 0 to 12. A higher score indicates better performance.

    10. Tablet Assessment: Time Estimation [Participants assessed pre-smoking and 1 hour, 2 hours, 4 hours, and 5 hours after smoking]

      The participant is to estimate the amount of time that has passed while performing a secondary task. This outcome is the ratio of 1) the estimated time that has passed (seconds), divided by 2) the actual amount of time that has passed. The range is from 0.204 to 1.89. A higher score indicates a better performance.

    11. Tablet Assessment: Balance [Participants assessed pre-smoking and 1 hour, 2 hours, 4 hours, and 5 hours after smoking]

      While standing and keeping their feet still, this is a measure of the participant's "sway", which is the total distance that the participant's body moved (in meters) from his/her initial vertical position. This was measured using an accelerometer placed on the participant's back. The range of scores is from .222 to 1.661. A higher score indicates worse performance.

    12. THC Concentrations: Correlation Between Blood and Oral Fluid [Approximately 15 minutes post-smoking]

      Spearman's correlation between THC concentrations in whole blood and oral fluid. Higher scores are better.

    13. THC Concentrations: Correlation Between Whole Blood and Breath [Approximately 15 minutes post-smoking]

      Spearman's correlation between THC concentrations in whole blood and breath

    Eligibility Criteria

    Criteria

    Ages Eligible for Study:
    21 Years to 55 Years
    Sexes Eligible for Study:
    All
    Accepts Healthy Volunteers:
    Yes
    Inclusion Criteria:
    • Be a licensed driver.

    • Need to have acuity of 20/40 or better, with or without correction on a Snellen Visual Acuity eye chart.

    Exclusion Criteria:
    • At the discretion of the examining physician, individuals with significant cardiovascular, hepatic or renal disease, uncontrolled hypertension, and chronic pulmonary disease (eg, asthma, COPD) will be excluded.

    • Unwillingness to abstain from cannabis for 2 days prior to screening and experimental visits

    • Positive pregnancy test

    • A positive result on toxicity screening for cocaine, amphetamines, opiates, and phencyclidine (PCP) will exclude individuals from participation.

    • Unwilling to refrain from driving or operating heavy machinery for four hours after consuming study medication.

    Contacts and Locations

    Locations

    Site City State Country Postal Code
    1 Center for Medicinal Cannabis Research, UC San Diego San Diego California United States 92103

    Sponsors and Collaborators

    • University of California, San Diego

    Investigators

    • Principal Investigator: Thomas D Marcotte, PhD, University of California, San Diego

    Study Documents (Full-Text)

    More Information

    Additional Information:

    Publications

    Responsible Party:
    Thomas D. Marcotte, PhD, Professor, University of California, San Diego
    ClinicalTrials.gov Identifier:
    NCT02849587
    Other Study ID Numbers:
    • 160641
    First Posted:
    Jul 29, 2016
    Last Update Posted:
    Jan 4, 2022
    Last Verified:
    Dec 1, 2021
    Individual Participant Data (IPD) Sharing Statement:
    Yes
    Plan to Share IPD:
    Yes
    Studies a U.S. FDA-regulated Drug Product:
    Yes
    Studies a U.S. FDA-regulated Device Product:
    No
    Keywords provided by Thomas D. Marcotte, PhD, Professor, University of California, San Diego
    Additional relevant MeSH terms:

    Study Results

    Participant Flow

    Recruitment Details
    Pre-assignment Detail
    Arm/Group Title Placebo Cannabis Cannabis With 5.9% THC Cannabis With 13.4% THC
    Arm/Group Description Participants will smoke placebo cannabis with .02% THC ad libitum Participants will smoke cannabis with 5.9% THC ad libitum Participants will smoke placebo cannabis with 13.4% THC ad libitum
    Period Title: Overall Study
    STARTED 65 70 64
    COMPLETED 63 66 62
    NOT COMPLETED 2 4 2

    Baseline Characteristics

    Arm/Group Title Placebo 5.9% THC 13.4% THC Total
    Arm/Group Description Cannabis with .02% THC Cannabis with 5.9% THC Cannabis with 13.4% THC Total of all reporting groups
    Overall Participants 63 66 62 191
    Age (years) [Mean (Standard Deviation) ]
    Mean (Standard Deviation) [years]
    28.1
    (7.3)
    30.7
    (8.8)
    30.9
    (8.6)
    29.9
    (8.3)
    Sex: Female, Male (Count of Participants)
    Female
    31
    49.2%
    19
    28.8%
    23
    37.1%
    73
    38.2%
    Male
    32
    50.8%
    47
    71.2%
    39
    62.9%
    118
    61.8%
    Race/Ethnicity, Customized (Count of Participants)
    African American
    8
    12.7%
    6
    9.1%
    4
    6.5%
    18
    9.4%
    Asian
    5
    7.9%
    8
    12.1%
    4
    6.5%
    17
    8.9%
    Hispanic
    15
    23.8%
    19
    28.8%
    22
    35.5%
    56
    29.3%
    Indigenous
    5
    7.9%
    2
    3%
    1
    1.6%
    8
    4.2%
    Multiracial
    2
    3.2%
    3
    4.5%
    2
    3.2%
    7
    3.7%
    Non-Hispanic White
    28
    44.4%
    28
    42.4%
    27
    43.5%
    83
    43.5%
    Unknown
    0
    0%
    0
    0%
    2
    3.2%
    2
    1%
    Region of Enrollment (participants) [Number]
    United States
    63
    100%
    66
    100%
    62
    100%
    191
    100%

    Outcome Measures

    1. Primary Outcome
    Title Change in Composite Drive Score (CDS) From Pre-smoking Simulation
    Description The Composite Drive Score (CDS) is a z-score comprised of key variables from the simulator tasks (SDLP, speed deviation, and task accuracy during the modified Surrogate Reference Task (mSuRT); coherence from the car following task). This outcome reflects the change in CDS from the pre-smoking assessment, at each timepoint. The z-score indicates the number of standard deviations away from the mean from the baseline performance for the entire group (n = 191). A Z-score of 0 is equal to the mean of a reference population (in this case the pre-smoking performance for the entire group). Higher z-scores at each timepoint indicate worse performance (variables that went in the opposite direction were reflected in order to have all variables have the same direction). When examining the change in Composite Drive Score (this outcome variable), a higher score indicates a decline in performance (e.g., Time 2 minus Time 1).
    Time Frame Participants are assessed pre-smoking, and then approximately 30m, 1h 30m, 3h 30m and 4h 30m post-smoking

    Outcome Measure Data

    Analysis Population Description
    [Not Specified]
    Arm/Group Title Placebo 5.9% THC 13.4% THC
    Arm/Group Description Placebo Cannabis Cannabis with 5.9% THC Cannabis with 13.4% THC
    Measure Participants 63 66 62
    Pre-smoke
    -.09
    (.64)
    .12
    (.58)
    .01
    (.52)
    30 minutes
    -.17
    (.61)
    .46
    (.60)
    .21
    (.60)
    1h 30min
    -.13
    (.61)
    .40
    (.66)
    .32
    (.59)
    3h 30min
    -.23
    (.59)
    .15
    (.64)
    .04
    (.57)
    4h 30min
    -.07
    (.66)
    .09
    (.57)
    .05
    (.59)
    Statistical Analysis 1
    Statistical Analysis Overview Comparison Group Selection Placebo, 5.9% THC, 13.4% THC
    Comments
    Type of Statistical Test Superiority
    Comments
    Statistical Test of Hypothesis p-Value <0.001
    Comments
    Method Generalized least squares model
    Comments
    2. Secondary Outcome
    Title Simulator: Standard Deviation of Lateral Position (SDLP)
    Description This measures the standard deviation of lateral (lane) position, or the degree to which the participant "swerves" within the road lane on the driving simulation during the modified Surrogate Reference Task (mSuRT). The range is from .39 to 3.33. A higher score indicates worse performance.
    Time Frame Participants are assessed pre-smoking, and then approximately 30m, 1h 30m, 3h 30m and 4h 30m post-smoking

    Outcome Measure Data

    Analysis Population Description
    [Not Specified]
    Arm/Group Title Placebo 5.9% THC 13.4% THC
    Arm/Group Description Placebo Cannabis Cannabis with 5.9% THC Cannabis with 13.4% THC
    Measure Participants 63 66 62
    Pre-smoking
    1.09
    (.36)
    1.20
    (.36)
    1.11
    (0.35)
    30 min
    1.07
    (.33)
    1.24
    (.36)
    1.19
    (.36)
    1h 30min
    1.06
    (.31)
    1.31
    (.39)
    1.23
    (.42)
    3h 30min
    1.10
    (.31)
    1.25
    (.35)
    1.20
    (.42)
    4h 30min
    1.10
    (.36)
    1.25
    (.37)
    1.18
    (.42)
    Statistical Analysis 1
    Statistical Analysis Overview Comparison Group Selection Placebo, 5.9% THC, 13.4% THC
    Comments
    Type of Statistical Test Superiority
    Comments
    Statistical Test of Hypothesis p-Value 0.022
    Comments
    Method Generalized least squares model
    Comments Raw data converted to z-score based on pre-smoking performance of entire sample.
    3. Secondary Outcome
    Title Simulator: Speed Deviation
    Description The variability in speed during the modified Surrogate Reference Test (mSuRT). The speed is in miles per hour. Range is from .17 to 12.85. A higher score indicates worse performance.
    Time Frame Participants are assessed pre-smoking, and then approximately 30m, 1h 30m, 3h 30m and 4h 30m post-smoking

    Outcome Measure Data

    Analysis Population Description
    [Not Specified]
    Arm/Group Title Placebo 5.9% THC 13.4% THC
    Arm/Group Description Placebo Cannabis Cannabis with 5.9% THC Cannabis with 13.4% THC
    Measure Participants 63 66 62
    Pre-smoking
    2.13
    (1.81)
    2.61
    (1.97)
    2.63
    (1.98)
    30 min
    2.03
    (1.31)
    3.04
    (1.71)
    2.99
    (2.05)
    1h 30min
    2.49
    (1.70)
    2.97
    (1.93)
    3.01
    (2.03)
    3h 30min
    2.15
    (1.89)
    3.04
    (2.16)
    2.65
    (1.72)
    4h 30min
    2.34
    (1.82)
    2.92
    (2.10)
    2.34
    (1.71)
    Statistical Analysis 1
    Statistical Analysis Overview Comparison Group Selection Placebo, 5.9% THC, 13.4% THC
    Comments
    Type of Statistical Test Superiority
    Comments
    Statistical Test of Hypothesis p-Value 0.283
    Comments
    Method Generalized least squares model
    Comments
    4. Secondary Outcome
    Title Simulator: Correct Hits on mSuRT
    Description The number of times the participant touched the correct stimulus (circle) on the iPad, during modified Surrogate Reference Task (mSuRT). Range is from 8 to 32. A higher score is a better score.
    Time Frame Participants are assessed pre-smoking, and then approximately 30m, 1h 30m, 3h 30m and 4h 30m post-smoking

    Outcome Measure Data

    Analysis Population Description
    [Not Specified]
    Arm/Group Title Placebo 5.9% THC 13.4% THC
    Arm/Group Description Placebo Cannabis Cannabis with 5.9% THC Cannabis with 13.4% THC
    Measure Participants 63 66 62
    Pre-smoking
    30.7
    (1.80)
    29.9
    (2.76)
    30.6
    (1.42)
    30 min
    30.9
    (1.71)
    28.7
    (4.23)
    30.3
    (2.54)
    1h 30min
    30.3
    (2.16)
    29.6
    (2.56)
    30.4
    (1.69)
    3h 30min
    30.4
    (2.73)
    29.7
    (2.61)
    30.7
    (1.40)
    4h 30min
    31.0
    (1.44)
    30.3
    (2.65)
    31.1
    (1.05)
    Statistical Analysis 1
    Statistical Analysis Overview Comparison Group Selection Placebo, 5.9% THC, 13.4% THC
    Comments
    Type of Statistical Test Superiority
    Comments
    Statistical Test of Hypothesis p-Value 0.0503
    Comments
    Method Generalized estimating equations model
    Comments
    5. Secondary Outcome
    Title Simulator: Car Following - Coherence
    Description Coherence is the correlation (0 to 1) between the participant and the lead car (which speeds up and slows down), representing the participant's ability to accurately speed up and slow down similarly to the lead car. Range of scores is from .01 to .97. A higher score is a better score.
    Time Frame Participants are assessed pre-smoking, and then approximately 30m, 1h 30m, 3h 30m and 4h 30m post-smoking

    Outcome Measure Data

    Analysis Population Description
    [Not Specified]
    Arm/Group Title Placebo 5.9% THC 13.4% THC
    Arm/Group Description Placebo Cannabis Cannabis with 5.9% THC Cannabis with 13.4% THC
    Measure Participants 63 66 62
    Pre-smoking
    .76
    (.19)
    .73
    (.18)
    .76
    (.15)
    30 min
    .79
    (.13)
    .66
    (.20)
    .71
    (.17)
    1h 30min
    .77
    (.16)
    .65
    (.23)
    .68
    (.19)
    3h 30min
    .80
    (.15)
    .74
    (.18)
    .74
    (.17)
    4h 30min
    .75
    (.16)
    .74
    (.18)
    .71
    (.17)
    Statistical Analysis 1
    Statistical Analysis Overview Comparison Group Selection Placebo, 5.9% THC, 13.4% THC
    Comments
    Type of Statistical Test Superiority
    Comments
    Statistical Test of Hypothesis p-Value 0.024
    Comments
    Method Generalized least squares model
    Comments
    6. Secondary Outcome
    Title Simulator: Response Delay - Car Following
    Description Time delay (in seconds) in responding to changes in the lead car's speed. Range is from -5.8 to 6.0. A higher score indicates a worse score.
    Time Frame Participants are assessed pre-smoking, and then approximately 30m, 1h 30m, 3h 30m and 4h 30m post-smoking

    Outcome Measure Data

    Analysis Population Description
    [Not Specified]
    Arm/Group Title Placebo 5.9% THC 13.4% THC
    Arm/Group Description Placebo Cannabis Cannabis with 5.9% THC Cannabis with 13.4% THC
    Measure Participants 63 66 62
    Pre-smoking
    2.92
    (1.15)
    3.32
    (1.23)
    3.58
    (1.24)
    30 min
    2.86
    (1.05)
    3.44
    (1.15)
    3.55
    (1.06)
    1h 30min
    2.80
    (.99)
    3.25
    (1.28)
    3.49
    (1.04)
    3h 30min
    2.61
    (1.04)
    2.83
    (1.05)
    3.23
    (1.18)
    4h 30min
    2.93
    (1.05)
    3.00
    (1.10)
    3.50
    (1.17)
    Statistical Analysis 1
    Statistical Analysis Overview Comparison Group Selection Placebo, 5.9% THC, 13.4% THC
    Comments
    Type of Statistical Test Superiority
    Comments
    Statistical Test of Hypothesis p-Value 0.716
    Comments
    Method Generalized least squares model
    Comments The outcome was standardized prior to analyses.
    7. Secondary Outcome
    Title Simulator: Distance From Lead Car - Car Following
    Description The outcome is distance from the lead car (in virtual feet) during the Car Following Task
    Time Frame Participants are assessed pre-smoking, and then approximately 30m, 1h 30m, 3h 30m and 4h 30m post-smoking

    Outcome Measure Data

    Analysis Population Description
    [Not Specified]
    Arm/Group Title Placebo 5.9% THC 13.4% THC
    Arm/Group Description Placebo Cannabis Cannabis with 5.9% THC Cannabis with 13.4% THC
    Measure Participants 63 66 62
    Pre-smoking
    153
    (41)
    156
    (41)
    163
    (35)
    30 min
    143
    (36)
    165
    (39)
    164
    (39)
    1h 30min
    144
    (34)
    160
    (38)
    165
    (36)
    3h 30min
    129
    (33)
    137
    (37)
    150
    (34)
    4h 30min
    138
    (34)
    136
    (37)
    151
    (36)
    Statistical Analysis 1
    Statistical Analysis Overview Comparison Group Selection Placebo, 5.9% THC, 13.4% THC
    Comments
    Type of Statistical Test Superiority
    Comments
    Statistical Test of Hypothesis p-Value 0.005
    Comments
    Method Generalized least squares model
    Comments The outcome was standardized prior to analysis.
    8. Secondary Outcome
    Title Tablet Assessment: Dual Attention Missed Switches
    Description The participant follows a moving target (square) with her/his finger, and switches to following a new stimulus when it appears in the corner of the screen. Each participant was classified as to whether he/she missed any of these switches during the trial. The outcome is the proportion of participants within each group who missed at least one switch. The range is from 0 to 1. Higher indicates a worse score.
    Time Frame Participants assessed pre-smoking and 1 hour, 2 hours, 4 hours, and 5 hours after smoking

    Outcome Measure Data

    Analysis Population Description
    [Not Specified]
    Arm/Group Title Placebo 5.9% THC 13.4% THC
    Arm/Group Description Placebo Cannabis Cannabis with 5.9% THC Cannabis with 13.4% THC
    Measure Participants 63 66 62
    Pre-smoking
    0.095
    0.2%
    0.145
    0.2%
    0.167
    0.3%
    1 hour
    0.095
    0.2%
    0.194
    0.3%
    0.183
    0.3%
    2 hours
    0.175
    0.3%
    0.161
    0.2%
    0.233
    0.4%
    4 hours
    0.191
    0.3%
    0.177
    0.3%
    0.167
    0.3%
    5 hours
    0.095
    0.2%
    0.129
    0.2%
    0.183
    0.3%
    Statistical Analysis 1
    Statistical Analysis Overview Comparison Group Selection Placebo, 5.9% THC, 13.4% THC
    Comments
    Type of Statistical Test Superiority
    Comments
    Statistical Test of Hypothesis p-Value .366
    Comments
    Method Generalized Estimating Equations model
    Comments
    9. Secondary Outcome
    Title Tablet Assessment: Lane Tracking Standard Deviation
    Description The participant is to rotate the iPad in order to keep a round object in the center, between two lines (lanes). This measure is the standard deviation of the position of the round object during the task (in essence, how much "swerving" there is within the lane). The range is from 8.2 to 189.4. A higher score indicates worse performance.
    Time Frame Participants assessed pre-smoking and 1 hour, 2 hours, 4 hours, and 5 hours after smoking

    Outcome Measure Data

    Analysis Population Description
    [Not Specified]
    Arm/Group Title Placebo 5.9% THC 13.4% THC
    Arm/Group Description Placebo Cannabis Cannabis with 13.4% THC Cannabis with 13.4% THC
    Measure Participants 63 66 62
    Pre-smoking
    26.9
    (9.53)
    30.9
    (23.7)
    27.2
    (9.67)
    1 hour
    28.7
    (13.4)
    30.9
    (15.7)
    32.1
    (21.7)
    2 hours
    28.4
    (10.3)
    27.6
    (10.2)
    27.4
    (10.4)
    4 hours
    28.1
    (13.3)
    29.9
    (15.5)
    28.6
    (14.8)
    5 hours
    26.4
    (10.8)
    25.4
    (8.39)
    25.3
    (13.8)
    Statistical Analysis 1
    Statistical Analysis Overview Comparison Group Selection Placebo, 5.9% THC, 13.4% THC
    Comments
    Type of Statistical Test Superiority
    Comments
    Statistical Test of Hypothesis p-Value .225
    Comments
    Method Generalized least squares model
    Comments Outcome was log10 transformed prior to analyses.
    10. Secondary Outcome
    Title Tablet Assessment: Visual Spatial Learning Test Number Correct
    Description Assessment of short-term memory for abstract figures. The participant is to memorize abstract figures and their locations on a 3 x 3 grid. After initial viewing (10 seconds), the figures go away for either 4, 12, or 24 seconds. The participant is then to identify which figures were in the initial viewing (from a list at the bottom of the screen), and place them at the correct location. This is the number of correctly identified figures. The range is from 0 to 12. A higher score indicates better performance.
    Time Frame Participants assessed pre-smoking and 1 hour, 2 hours, 4 hours, and 5 hours after smoking

    Outcome Measure Data

    Analysis Population Description
    [Not Specified]
    Arm/Group Title Placebo 5.9% THC 13.4% THC
    Arm/Group Description Placebo Cannabis Cannabis with 5.9% THC Cannabis with 13.4% THC
    Measure Participants 63 66 62
    Pre-smoking
    9.9
    (2.3)
    9.7
    (2.7)
    10.1
    (2.2)
    1 hour
    9.1
    (2.8)
    8.4
    (2.6)
    9.3
    (2.7)
    2 hours
    8.9
    (3.1)
    8.7
    (2.6)
    8.9
    (2.7)
    4 hours
    8.5
    (3.0)
    8.3
    (2.9)
    8.8
    (2.5)
    5 hours
    9.3
    (2.9)
    8.5
    (3.0)
    9.5
    (3.0)
    Statistical Analysis 1
    Statistical Analysis Overview Comparison Group Selection Placebo, 5.9% THC, 13.4% THC
    Comments
    Type of Statistical Test Superiority
    Comments
    Statistical Test of Hypothesis p-Value .592
    Comments
    Method Generalized least squares model
    Comments The outcome was transformed using logit function prior to analyses. Model included treatment (3 groups), time (5 times), and their interaction.
    11. Secondary Outcome
    Title Tablet Assessment: Time Estimation
    Description The participant is to estimate the amount of time that has passed while performing a secondary task. This outcome is the ratio of 1) the estimated time that has passed (seconds), divided by 2) the actual amount of time that has passed. The range is from 0.204 to 1.89. A higher score indicates a better performance.
    Time Frame Participants assessed pre-smoking and 1 hour, 2 hours, 4 hours, and 5 hours after smoking

    Outcome Measure Data

    Analysis Population Description
    [Not Specified]
    Arm/Group Title Placebo 5.9% THC 13.4% THC
    Arm/Group Description Placebo Cannabis Cannabis with 5.9% THC Cannabis with 13.4% THC
    Measure Participants 63 66 62
    Pre-smoking
    0.75
    (0.19)
    0.83
    (0.30)
    0.77
    (0.22)
    1 hour
    0.79
    (0.21)
    0.89
    (0.30)
    0.85
    (0.24)
    2 hours
    0.83
    (0.20)
    0.96
    (0.30)
    0.87
    (0.27)
    4 hours
    0.85
    (0.23)
    0.93
    (0.23)
    0.86
    (0.21)
    5 hours
    0.83
    (0.20)
    0.89
    (0.28)
    0.85
    (0.21)
    Statistical Analysis 1
    Statistical Analysis Overview Comparison Group Selection Placebo, 5.9% THC, 13.4% THC
    Comments
    Type of Statistical Test Superiority
    Comments
    Statistical Test of Hypothesis p-Value .294
    Comments
    Method Generalized least squares model
    Comments
    12. Secondary Outcome
    Title Tablet Assessment: Balance
    Description While standing and keeping their feet still, this is a measure of the participant's "sway", which is the total distance that the participant's body moved (in meters) from his/her initial vertical position. This was measured using an accelerometer placed on the participant's back. The range of scores is from .222 to 1.661. A higher score indicates worse performance.
    Time Frame Participants assessed pre-smoking and 1 hour, 2 hours, 4 hours, and 5 hours after smoking

    Outcome Measure Data

    Analysis Population Description
    [Not Specified]
    Arm/Group Title Placebo 5.9% THC 13.4% THC
    Arm/Group Description Placebo Cannabis Cannabis with 5.9% THC Cannabis with 13.4% THC
    Measure Participants 63 66 62
    Pre-smoking
    0.358
    (0.058)
    0.360
    (0.067)
    0.356
    (0.058)
    1 hour
    0.342
    (0.054)
    0.376
    (0.090)
    0.363
    (0.129)
    2 hours
    0.351
    (0.053)
    0.394
    (0.161)
    0.414
    (0.254)
    4 hours
    0.354
    (0.058)
    0.386
    (0.131)
    0.377
    (0.133)
    5 hours
    0.368
    (0.059)
    0.371
    (0.054)
    0.365
    (0.072)
    Statistical Analysis 1
    Statistical Analysis Overview Comparison Group Selection Placebo, 5.9% THC, 13.4% THC
    Comments
    Type of Statistical Test Superiority
    Comments
    Statistical Test of Hypothesis p-Value .144
    Comments
    Method Generalized least squares model
    Comments
    13. Secondary Outcome
    Title THC Concentrations: Correlation Between Blood and Oral Fluid
    Description Spearman's correlation between THC concentrations in whole blood and oral fluid. Higher scores are better.
    Time Frame Approximately 15 minutes post-smoking

    Outcome Measure Data

    Analysis Population Description
    [Not Specified]
    Arm/Group Title Placebo 5.9% THC 13.4% THC
    Arm/Group Description Placebo cannabis Participants smoking 5.9% THC cannabis Group smoking 13.4% THC
    Measure Participants 63 66 62
    Number (95% Confidence Interval) [Spearman's rho]
    0.217
    0.414
    0.249
    Statistical Analysis 1
    Statistical Analysis Overview Comparison Group Selection Placebo
    Comments
    Type of Statistical Test Other
    Comments Spearman's correlation
    Statistical Test of Hypothesis p-Value 0.090
    Comments
    Method Spearman's correlation
    Comments
    Statistical Analysis 2
    Statistical Analysis Overview Comparison Group Selection 5.9% THC
    Comments
    Type of Statistical Test Other
    Comments Spearman's correlation
    Statistical Test of Hypothesis p-Value .0006
    Comments
    Method Spearman's correlation
    Comments
    Statistical Analysis 3
    Statistical Analysis Overview Comparison Group Selection 13.4% THC
    Comments
    Type of Statistical Test Other
    Comments Spearman's correlation
    Statistical Test of Hypothesis p-Value 0.053
    Comments
    Method Spearman's correlation
    Comments
    14. Secondary Outcome
    Title THC Concentrations: Correlation Between Whole Blood and Breath
    Description Spearman's correlation between THC concentrations in whole blood and breath
    Time Frame Approximately 15 minutes post-smoking

    Outcome Measure Data

    Analysis Population Description
    [Not Specified]
    Arm/Group Title Placebo 5.9% THC 13.4% THC
    Arm/Group Description Placebo cannabis Cannabis with 5.9% THC Cannabis with 13.4% THC
    Measure Participants 63 66 62
    Number (95% Confidence Interval) [Spearman's rho]
    0.134
    -0.258
    -0.176
    Statistical Analysis 1
    Statistical Analysis Overview Comparison Group Selection Placebo
    Comments
    Type of Statistical Test Other
    Comments Spearman's correlation
    Statistical Test of Hypothesis p-Value 0.300
    Comments
    Method Spearman's correlation
    Comments
    Statistical Analysis 2
    Statistical Analysis Overview Comparison Group Selection 5.9% THC
    Comments
    Type of Statistical Test Other
    Comments Spearman's correlation
    Statistical Test of Hypothesis p-Value 0.038
    Comments
    Method Spearman's correlation
    Comments
    Statistical Analysis 3
    Statistical Analysis Overview Comparison Group Selection 13.4% THC
    Comments
    Type of Statistical Test Other
    Comments Spearman's correlation
    Statistical Test of Hypothesis p-Value 0.175
    Comments
    Method Spearman's correlation
    Comments

    Adverse Events

    Time Frame One day (acute administration)
    Adverse Event Reporting Description
    Arm/Group Title Placebo Cannabis Cannabis With 5.9% THC Cannabis With 13.4% THC
    Arm/Group Description Placebo Cannabis (.02% THC) Cannabis with 5.9% THC, smoked ad libitum Cannabis with 13.4% THC, smoked ad libitum
    All Cause Mortality
    Placebo Cannabis Cannabis With 5.9% THC Cannabis With 13.4% THC
    Affected / at Risk (%) # Events Affected / at Risk (%) # Events Affected / at Risk (%) # Events
    Total 0/65 (0%) 0/70 (0%) 0/64 (0%)
    Serious Adverse Events
    Placebo Cannabis Cannabis With 5.9% THC Cannabis With 13.4% THC
    Affected / at Risk (%) # Events Affected / at Risk (%) # Events Affected / at Risk (%) # Events
    Total 0/65 (0%) 0/70 (0%) 0/64 (0%)
    Other (Not Including Serious) Adverse Events
    Placebo Cannabis Cannabis With 5.9% THC Cannabis With 13.4% THC
    Affected / at Risk (%) # Events Affected / at Risk (%) # Events Affected / at Risk (%) # Events
    Total 2/65 (3.1%) 15/70 (21.4%) 5/64 (7.8%)
    Cardiac disorders
    Heart Rate Abnormal 0/65 (0%) 0 12/70 (17.1%) 12 1/64 (1.6%) 1
    Gastrointestinal disorders
    Nausea 0/65 (0%) 0 2/70 (2.9%) 2 1/64 (1.6%) 1
    General disorders
    Cervicalgia 0/65 (0%) 0 1/70 (1.4%) 1 0/64 (0%) 0
    Fever 0/65 (0%) 0 1/70 (1.4%) 1 0/64 (0%) 0
    Injury, poisoning and procedural complications
    Discomfort in arm 1/65 (1.5%) 1 1/70 (1.4%) 1 0/64 (0%) 0
    Swollen arm 0/65 (0%) 0 0/70 (0%) 0 1/64 (1.6%) 1
    Numbness in arm 1/65 (1.5%) 1 0/70 (0%) 0 0/64 (0%) 0
    Nervous system disorders
    Dizziness 0/65 (0%) 0 3/70 (4.3%) 3 3/64 (4.7%) 3
    Sweats 0/65 (0%) 0 2/70 (2.9%) 2 0/64 (0%) 0
    Psychiatric disorders
    Anxiety 0/65 (0%) 0 2/70 (2.9%) 2 0/64 (0%) 0
    Respiratory, thoracic and mediastinal disorders
    Cough 0/65 (0%) 0 0/70 (0%) 0 1/64 (1.6%) 1
    Vascular disorders
    Blood Pressure Decreased 0/65 (0%) 0 3/70 (4.3%) 3 1/64 (1.6%) 1
    Blood Pressure Increased 0/65 (0%) 0 2/70 (2.9%) 2 0/64 (0%) 0
    Fainting 0/65 (0%) 0 1/70 (1.4%) 1 0/64 (0%) 0

    Limitations/Caveats

    [Not Specified]

    More Information

    Certain Agreements

    All Principal Investigators ARE employed by the organization sponsoring the study.

    There is NOT an agreement between Principal Investigators and the Sponsor (or its agents) that restricts the PI's rights to discuss or publish trial results after the trial is completed.

    Results Point of Contact

    Name/Title Thomas D. Marcotte, Phd
    Organization University of California, San Diego; Center for Medicinal Cannabis Research
    Phone 619-543-5044
    Email tmarcotte@ucsd.edu
    Responsible Party:
    Thomas D. Marcotte, PhD, Professor, University of California, San Diego
    ClinicalTrials.gov Identifier:
    NCT02849587
    Other Study ID Numbers:
    • 160641
    First Posted:
    Jul 29, 2016
    Last Update Posted:
    Jan 4, 2022
    Last Verified:
    Dec 1, 2021