Perceived effects of cannabis: Generalizability of changes in driving performance.
Thomas S Burt, Timothy L Brown, Rose Schmitt, Daniel McGehee, Gary Milavetz, Gary R Gaffney, Chris Berka
Traffic injury prevention 2022 DOI: 10.1080/15389588.2022.2128787 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Secondary analysis of an experimental study Longitudinal Peer reviewed |
|---|---|
| Sample size | 52 |
| Population | Drivers who used cannabis in a study examining effects of cannabis on driving performance |
| Intervention | Placebo |
| Dose | 6.18% delta-9-tetrahydrocannabinol (THC) |
| Measures | standard deviation of lane position (SDLP) |
| Topics | Cannabis |
| Keywords | Driving Objective performance Perceived impairment |
| Key findings | Subjective perceptions of acute cannabis impairment remained significant predictors of driving performance and explained individual variability beyond acute cannabis use alone. However, the specific subjective predictors differed between the current 52-subject sample and a prior 10-subject study, and the authors conclude that generalizability of these findings is lacking because subjective effects were significant inconsistently across studies. |
Abstract
The objective of this analysis was to determine the generalizability of the relationship between different samples of a driver's perceived state after cannabis use and related performance while operating a motor vehicle. Data were collected from 52 subjects in a study examining the effects of cannabis on driving performance. Data were analyzed using the SAS GLM Select procedure, using stepwise selection, with subjective effects, dosing condition (placebo vs. 6.18% delta-9-tetrahydrocannabinol [THC]), and driving context as independent measures. Correlation matrices of measures of driving performance against subjective responses and dosing condition used Pearson's and Spearman's test statistics, respectively. Results were compared to a prior study from a sample of 10 subjects. Subjective perceptions of acute cannabis impairment remain significant predictors of driving performance and explain individual variability in driving performance degradation as well as the data, beyond that which can be explained by acute use of cannabis alone. However, the significant subjective predictors of driving performance differ between the current and prior studies. To better understand these differences, correlations between subjective effects and performance measures were evaluated, which revealed that most correlations matched directionally (e.g., an increase in "good drug effect" was correlated with an increase in standard deviation of lane position [SDLP]). When there was a mismatch, 1 or more correlations were insignificant. Dosing condition and "stoned" were perfectly consistent; "high" and "sedated" contained 1 mismatch; and "anxious," "good drug effect" and "restless" contained 3 or more mismatches. The results indicate that across both studies, differences in the perceived effects of cannabis are reflected in changes in both lateral and longitudinal control beyond the acute effects of cannabis, which may help explain individual variability in response to acute intoxication. However, the generalizability of these findings is lacking, as shown by inconsistencies in when and where subjective effects were significant. Other factors such as frequency of use, usage type, the evolving profile of a cannabis user, as well as other individual differences should be considered to explain this additional variability.
Comparable studies
Other experimental studies on cannabis, most cited first.
| Study | Year | Design | Participants |
|---|---|---|---|
| Smoked Cannabis' Psychomotor and Neurocognitive Effects in Occasional and Frequent Smokers Occasional (<2x/week) and frequent (≥4x/week) cannabis smokers | 2015 | Controlled within-subjects study | n = 25 |
| Dissociable effects of cannabis with and without cannabidiol on the human brain’s resting-state functional connectivity Healthy volunteers experienced with cannabis but not regular users | 2019 | Within-subjects experimental design | n = 17 |
| Which biological and self-report measures of cannabis use predict cannabis dependency and acute psychotic-like effects? Young cannabis users | 2018 | Observational study (naturalistic, within-subject counterbalanced design) | n = 410 |
| Cannabis Essential Oil: A Preliminary Study for the Evaluation of the Brain Effects Healthy volunteers | 2018 | Experimental study | n = 5 |
| Coming off cannabis: a cognitive and magnetic resonance imaging study in patients with multiple sclerosis Patients with multiple sclerosis who began using cannabis after disease onset, used it... | 2019 | Quasi-experimental study with odd-even allocation | n = 40 |
Citations in the library
Cites 3
- Perceived effects of cannabis and changes in driving performance under the influence of cannabis. Traffic injury prevention 2021
- Cannabis effects on driving longitudinal control with and without alcohol. Journal of Applied Toxicology November 2016
- Acute and Chronic Effects of Cannabinoids on Human Cognition-A Systematic Review. Biological Psychiatry April 1, 2016