Attitudes and outcome expectancies about driving after alcohol and marijuana use [abstract]

Abstract

Alcohol is estimated to be involved in 41% of all fatal crashes (NHTSA, 2001). Less is known about driving under the influence of marijuana. However, marijuana is known to cause cognitive, motor and perceptual difficulties that can affect driving ability (NIDA, 1998). Studies have also found that a high percentage of reckless drivers who had not used alcohol test positive for marijuana (Brookoff, et al, 1994). The objective of this study is to identify factors associated with driving under the influence of alcohol or marijuana. We are conducting a questionnaire study examining substance use behaviors of approximately 250 college students. The study will examine three predictors of substance-related driving: 1) amount and frequency of substance use (alcohol and marijuana), 2) outcome expectancies, or perceived effects, of alcohol and marijuana, and 3) specific cognitions about the risks associated with driving after use of either substance. Prior research has found these factors to be associated with driving after use of alcohol, although this has not been tested for driving after use of marijuana. Hierarchical regression analyses will be used to examine predictors of substance-related driving. Analyses will be conducted separately for driving after alcohol use and driving after use of marijuana. For each analysis, substance use (marijuana/alcohol) will be entered first. Outcome expectancies about the specific substance will be entered on the second step. Finally, cognitions about driving after using substances will be added. Additional analyses will be conducted to compare participant's perceived risk of driving after marijuana use with the perceived risk of driving after drinking. We hypothesize that college age youth will perceive driving after use of marijuana to be less dangerous and to have less potential consequences than driving after use of alcohol.