ABSTRACT Driving under the influence of cannabis (DUIC) nearly doubles car crash risk, with medical cannabis (MC) patients representing an at-risk group for DUIC. This R21 aims to advance efforts to reduce DUIC through the innovative combination of a smartphone app for objective detection of aberrant driving behaviors, Ecological Momentary Assessment (EMA), and biological sampling (delta-9-tetra-hydrocannabinol: THC; cannabidiol: CBD) to examine effects of cannabis use on driving behavior in real-world conditions among MC patients. This project builds on recent work, which examined both THC and CBD in relation to real-world driving behavior, and addresses limitations of prior work by using EMA to obtain fine-grained data on subjective cannabis effects prior to driving over an extended period (up to 28 days), in addition to collecting a biological sample (THC, CBD) prior to driving for exploratory comparison with EMA report. This R21 also will assess "effort put into driving" (i.e., compensatory effort for cannabis effects) since certain driving behaviors might be modified by "effort" to counteract cannabis effects, whereas other driving behaviors may be less subject to compensatory behaviors. R21 project aims are to: (1) Determine the extent to which THC, based on MC product labeling and self-reported quantity used, are associated with aberrant driving behavior (e.g., sudden braking, weaving) in real life; (2) Examine how EMA report of subjective cannabis intoxication, chronicity of cannabis use, and "effort put into driving" are associated with aberrant driving behavior (e.g., sudden braking) in real life; Exploratory aim: Examine THC and CBD (biological sample prior to driving) as predictors of aberrant driving in real world conditions. To achieve these aims, this R21 will recruit eligible MC patients (N=70, 50% female) for Pilot (n=10) and Study (n=60) phases. In both phases, participants complete a baseline lab assessment, followed by daily data collection (EMA; phone sensor data collection for objective detection of driving behavior with high accuracy: >96%), collection of a biological sample prior to driving (concurrent with EMA report prior to driving) for one week, and a final post-data collection lab assessment and qualitative interview. Study Phase will use qualitative data to refine the app and identify new app features to be added to prevent DUIC in future work. Analyses will explore gender differences. The innovative use of a smartphone app for objective detection of aberrant driving behavior, combined with EMA and biological sampling (THC, CBD), will provide important, new findings on effects (subjective and objective) of cannabis (THC, CBD) and compensatory "effort" on driving behavior in daily life in MC patients to enable urgently needed advances to reduce DUIC.

Project Narrative This exploratory study combines innovative smartphone monitoring of driving behavior with daily data collection (self-report, saliva sample) to examine effects of cannabis on driving behavior in real-world conditions among medical cannabis patients. The project focuses on medical cannabis patients due, in part, to greater access to information on cannabis content based on product labeling (THC, CBD). Study results have important public health implications for guiding efforts to prevent driving under the influence of cannabis.