Trial · NCT02849587

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

NCT02849587, Phase 1, Phase 2, Completed, University of California, San Diego; results first posted 2022-01-04

3 sourcestrials-2026-11-12-0.5.0

Cite this record

ConductScience Library. The Impact and Detection of Driving Impairments Associated With Acute Cannabis Smoking. Trials, record NCT02849587. Release trials-2026-11-12-0.5.0, 12 Nov 2026. https://conductscience.org/library/trials/NCT02849587

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Trial

As registered on ClinicalTrials.gov, in the graph's capture of the registry.

Title: The Impact and Detection of Driving Impairments Associated With Acute Cannabis Smoking
NCT number: NCT02849587
Status: Completed
Phases: Phase 1, Phase 2
Enrollment: 199 participants, actual
Lead sponsor: University of California, San Diego
Conditions: Cannabis Intoxication
Interventions: Cannabis
First posted: 2016-07-29
Last updated: 2022-01-04
Results first posted: 2022-01-04

Source ClinicalTrials.gov

Registered outcomes14

Each outcome the trial registered, primary first, in ClinicalTrials.gov's words.

List	Outcome	Time frame	Description
Primary	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	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.
Secondary	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.
Secondary	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.
Secondary	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.
Secondary	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.
Secondary	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
Secondary	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.
Secondary	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.
Secondary	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.

1 to 10 of 14Source ClinicalTrials.gov

See all 14 registered outcomes

Outcomes14

Each outcome the trial posted results for, in ClinicalTrials.gov's words.

Type	Outcome	Time frame	Units	Measured as
PRIMARY	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	z-score	MEAN
SECONDARY	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	z-score	MEAN
SECONDARY	Simulator: Speed Deviation	Participants are assessed pre-smoking, and then approximately 30m, 1h 30m, 3h 30m and 4h 30m post-smoking	miles per hour	MEAN
SECONDARY	Simulator: Correct Hits on mSuRT	Participants are assessed pre-smoking, and then approximately 30m, 1h 30m, 3h 30m and 4h 30m post-smoking	count of correct responses	MEAN
SECONDARY	Simulator: Car Following - Coherence	Participants are assessed pre-smoking, and then approximately 30m, 1h 30m, 3h 30m and 4h 30m post-smoking	Correlation coefficient	MEAN
SECONDARY	Simulator: Response Delay - Car Following	Participants are assessed pre-smoking, and then approximately 30m, 1h 30m, 3h 30m and 4h 30m post-smoking	seconds	MEAN
SECONDARY	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	feet	MEAN
SECONDARY	Tablet Assessment: Dual Attention Missed Switches	Participants assessed pre-smoking and 1 hour, 2 hours, 4 hours, and 5 hours after smoking	Proportion of participants	MEAN
SECONDARY	Tablet Assessment: Lane Tracking Standard Deviation	Participants assessed pre-smoking and 1 hour, 2 hours, 4 hours, and 5 hours after smoking	standard deviation of position	MEAN
SECONDARY	Tablet Assessment: Visual Spatial Learning Test Number Correct	Participants assessed pre-smoking and 1 hour, 2 hours, 4 hours, and 5 hours after smoking	number of correct responses	MEAN

1 to 10 of 14Source ClinicalTrials.gov

See all 14 outcomes

Results by group186

Each measurement the trial posted, group by group, in the words and numbers it posted.

Outcome	Group	Category	Value	Spread	Units
Change in Composite Drive Score (CDS) From Pre-smoking Simulation	Placebo	Pre-smoke	-.09	Standard Deviation .64	z-score
Change in Composite Drive Score (CDS) From Pre-smoking Simulation	5.9% THC	Pre-smoke	.12	Standard Deviation .58	z-score
Change in Composite Drive Score (CDS) From Pre-smoking Simulation	13.4% THC	Pre-smoke	.01	Standard Deviation .52	z-score
Change in Composite Drive Score (CDS) From Pre-smoking Simulation	Placebo	30 minutes	-.17	Standard Deviation .61	z-score
Change in Composite Drive Score (CDS) From Pre-smoking Simulation	5.9% THC	30 minutes	.46	Standard Deviation .60	z-score
Change in Composite Drive Score (CDS) From Pre-smoking Simulation	13.4% THC	30 minutes	.21	Standard Deviation .60	z-score
Change in Composite Drive Score (CDS) From Pre-smoking Simulation	Placebo	1h 30min	-.13	Standard Deviation .61	z-score
Change in Composite Drive Score (CDS) From Pre-smoking Simulation	5.9% THC	1h 30min	.40	Standard Deviation .66	z-score
Change in Composite Drive Score (CDS) From Pre-smoking Simulation	13.4% THC	1h 30min	.32	Standard Deviation .59	z-score
Change in Composite Drive Score (CDS) From Pre-smoking Simulation	Placebo	3h 30min	-.23	Standard Deviation .59	z-score

1 to 10 of 186Source ClinicalTrials.gov

See all 186 results by group

Participant flow9

How many started, completed or left each group, period by period.

Period	Milestone	Group	Participants
Overall Study	STARTED	Placebo Cannabis	65
Overall Study	STARTED	Cannabis With 5.9% THC	70
Overall Study	STARTED	Cannabis With 13.4% THC	64
Overall Study	COMPLETED	Placebo Cannabis	63
Overall Study	COMPLETED	Cannabis With 5.9% THC	66
Overall Study	COMPLETED	Cannabis With 13.4% THC	62
Overall Study	NOT COMPLETED	Placebo Cannabis	2
Overall Study	NOT COMPLETED	Cannabis With 5.9% THC	4
Overall Study	NOT COMPLETED	Cannabis With 13.4% THC	2

Source ClinicalTrials.gov

Adverse events42

Each adverse event the trial posted, group by group: the participants affected out of those at risk.

Type	Event	Organ system	Group	Affected	At risk	Events
other	Anxiety	Psychiatric disorders	Placebo Cannabis	0	65	0
other	Anxiety	Psychiatric disorders	Cannabis With 5.9% THC	2	70	2
other	Anxiety	Psychiatric disorders	Cannabis With 13.4% THC	0	64	0
other	Dizziness	Nervous system disorders	Placebo Cannabis	0	65	0
other	Dizziness	Nervous system disorders	Cannabis With 5.9% THC	3	70	3
other	Dizziness	Nervous system disorders	Cannabis With 13.4% THC	3	64	3
other	Nausea	Gastrointestinal disorders	Placebo Cannabis	0	65	0
other	Nausea	Gastrointestinal disorders	Cannabis With 5.9% THC	2	70	2
other	Nausea	Gastrointestinal disorders	Cannabis With 13.4% THC	1	64	1
other	Sweats	Nervous system disorders	Placebo Cannabis	0	65	0

1 to 10 of 42Source ClinicalTrials.gov

See all 42 adverse events

Adverse event totals9

The totals the trial posted for each group.

Total	Group	Affected	At risk
Total, all-cause mortality	Placebo Cannabis	0	65
Total, all-cause mortality	Cannabis With 5.9% THC	0	70
Total, all-cause mortality	Cannabis With 13.4% THC	0	64
Total, other adverse events	Placebo Cannabis	2	65
Total, other adverse events	Cannabis With 5.9% THC	15	70
Total, other adverse events	Cannabis With 13.4% THC	5	64
Total, serious adverse events	Placebo Cannabis	0	65
Total, serious adverse events	Cannabis With 5.9% THC	0	70
Total, serious adverse events	Cannabis With 13.4% THC	0	64

Source ClinicalTrials.gov

Papers12

The papers the trial lists on ClinicalTrials.gov.

PMID	Listed as	Source
10645701	BACKGROUND	PubMed
15619106	BACKGROUND	PubMed
18760160	BACKGROUND	PubMed
23045289	BACKGROUND	PubMed
23220273	BACKGROUND	PubMed
24202191	BACKGROUND	PubMed
30615854	RESULT	PubMed
31527291	RESULT	PubMed
34173005	RESULT	PubMed
34185831	RESULT	PubMed

1 to 10 of 12

See all 12 papers

Grants0

The grants NIH RePORTER links to the trial, newest funded first: NIH's, and some of AHRQ's, CDC's, FDA's and VA's. Each shows its title, principal investigators, organization and funder in its newest year.

None in this release.

Trial comparisons0

Comparisons of the trial's two groups, calculated by ConductScience from the counts it posted.

None in this release.

Tests0

The ConductCognition tests this trial's registered outcomes name, as ScienceGraph matched them in trial-tests-2026-11-12-0.2.1.

None in this release.

Data dates

The day each source was copied for this release.

ClinicalTrials.gov: 2026-11-12; ClinicalTrials.gov
Results, from AACT: 2026-03-23; AACT
NIH grant links: 2026-11-13; NIH RePORTER

Sources 3

ClinicalTrials.gov's posted results, through CTTI's AACTFreely available. Acknowledgement requested
ClinicalTrials.govNo license stated
NIH RePORTER's clinical studies and project filesPublic domain

Each source's terms

ClinicalTrials.gov's posted results, through CTTI's AACTClinicalTrials.gov data via Aggregate Analysis of ClinicalTrials.gov (AACT), CTTI. CTTI makes its materials freely available and requests acknowledgement. https://aact.ctti-clinicaltrials.org/documentation/299
ClinicalTrials.govnone stated
NIH RePORTER's clinical studies and project filesPublic domain (NIH RePORTER)

ClinicalTrials.gov's data carry an international copyright outside the United States: https://clinicaltrials.gov/about-site/terms-conditions.

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