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- Title
Cannabis and Driving in Older Adults.
- Authors
Di Ciano, Patricia; Rajji, Tarek K.; Hong, Lauren; Zhao, Sampson; Byrne, Patrick; Elzohairy, Yoassry; Brubacher, Jeffrey R.; McGrath, Michael; Brands, Bruna; Chen, Sheng; Wang, Wei; Hasan, Omer S. M.; Wickens, Christine M.; Kaduri, Pamela; Le Foll, Bernard
- Abstract
This cohort study evaluates the association between cannabis and simulated driving along with concurrent blood tetrahydrocannabinol levels in older adults in Canada. Key Points: Question: What is the association between retail cannabis available to the consumer, driving, and associated blood tetrahydrocannabinol (THC) levels in people over 65 years of age? Findings: In this cohort study, 31 regular users of cannabis aged 65 to 79 years chose on average high potency (18.74% THC) THC-dominant cannabis. Weaving was increased and speed was decreased at 30 minutes after smoking, which was not correlated with blood THC concentrations; subjective experience and self-reports of impaired driving persisted for 3 hours. Meaning: These findings suggest that older drivers, even if they regularly use cannabis, show evidence of impaired driving performance after smoking cannabis. Importance: Epidemiological studies have found that cannabis increases the risk of a motor vehicle collision. Cannabis use is increasing in older adults, but laboratory studies of the association between cannabis and driving in people aged older than 65 years are lacking. Objective: To investigate the association between cannabis, simulated driving, and concurrent blood tetrahydrocannabinol (THC) levels in older adults. Design, Setting, and Participants: Using an ecologically valid counterbalanced design, in this cohort study, regular cannabis users operated a driving simulator before, 30 minutes after, and 180 minutes after smoking their preferred legal cannabis or after resting. This study was conducted in Toronto, Canada, between March and November 2022 with no follow-up period. Data were analyzed from December 2022 to February 2023. Exposures: Most participants chose THC-dominant cannabis with a mean (SD) content of 18.74% (6.12%) THC and 1.46% (3.37%) cannabidiol (CBD). Main outcomes and measures: The primary end point was SD of lateral position (SDLP, or weaving). Secondary outcomes were mean speed (MS), maximum speed, SD of speed, and reaction time. Driving was assessed under both single-task and dual-task (distracted) conditions. Blood THC and metabolites of THC and CBD were also measured at the time of the drives. Results: A total of 31 participants (21 male [68%]; 29 White [94%], 1 Latin American [3%], and 1 mixed race [3%]; mean [SD] age, 68.7 [3.5] years), completed all study procedures. SDLP was increased and MS was decreased at 30 but not 180 minutes after smoking cannabis compared with the control condition in both the single-task (SDLP effect size [ES], 0.30; b = 1.65; 95% CI, 0.37 to 2.93; MS ES, −0.58; b = −2.46; 95% CI, −3.56 to −1.36) and dual-task (SDLP ES, 0.27; b = 1.75; 95% CI, 0.21 to 3.28; MS ES, −0.47; b = −3.15; 95% CI, −5.05 to −1.24) conditions. Blood THC levels were significantly increased at 30 minutes but not 180 minutes. Blood THC was not correlated with SDLP or MS at 30 minutes, and SDLP was not correlated with MS. Subjective ratings remained elevated for 5 hours and participants reported that they were less willing to drive at 3 hours after smoking. Conclusions and relevance: In this cohort study, the findings suggested that older drivers should exercise caution after smoking cannabis.
- Subjects
CANADA; CANNABIDIOL; CANNABIS (Genus); CENTRAL nervous system stimulants; CONFIDENCE intervals; INTERVIEWING; HYDROCARBONS; PEARSON correlation (Statistics); AUTOMOBILE driving; DESCRIPTIVE statistics; RESEARCH funding; DATA analysis software; LONGITUDINAL method; OLD age
- Publication
JAMA Network Open, 2024, Vol 7, Issue 1, pe2352233
- ISSN
2574-3805
- Publication type
Article
- DOI
10.1001/jamanetworkopen.2023.52233