There have been extensive studies on the effects of alcohol on drivers, and research has also analyzed the ways that marijuana may impact driving proficiency. However, the legalization of marijuana may significantly increase the instances in which alcohol and marijuana are consumed together.
The use of marijuana while or before driving is an important public health concern. The Office of National Drug Control Policy, for instance, is tasking itself with reducing drugged driving by 10 percent before 2015.
Study Testing Alcohol And Marijuana’s Effects On Driving
A study highlighted in Basis Online documents the potential for impaired driving when alcohol and marijuana are combined (Downey et al., 2013). The researchers studied the effects of marijuana, both alone and in combination with alcohol, on the driving ability of 80 participants. Half of the participants were regular users of marijuana and the remaining were not regular users.
The participants were divided into two groups: low alcohol (0.04 percent blood alcohol content) and high alcohol (0.06 percent blood alcohol content). In both groups, the participants were enrolled in six sessions that varied in the concentrations of alcohol and marijuana consumed. With both the alcohol and the marijuana, the participants were given a placebo at either a low dose or a high dose.
In each instance, the researchers gave the participants a beverage and then gave them a placebo or a marijuana cigarette. A breath and blood sample both confirmed the status of blood alcohol content and THC among the participants.
The participants were administered a daytime and a nighttime driving simulation exercise. Overall driving impairment was measured, as well as speed, distance and a potential 19 errors.
The team also measured the effects of the participants’ normal cannabis use, whether regular or non-existent, as well as alcohol use, on their driving simulation.
The article focused on the results of a set of nighttime driving exercises. Those in the groups that had a low level of marijuana and alcohol and those in the group that had a high level of marijuana and alcohol scored significantly worse on driving impairment than those in the placebo condition. Those in the high marijuana plus placebo were less impaired than any of the conditions that included alcohol.
The authors note several limitations to the findings. The team only examined the impact of legal blood alcohol content levels, so the results don’t reflect the potential outcomes of those who drink more heavily. In addition, the driving simulation may not accurately reflect the conditions that would be present in a real driving situation.
The research suggests that the combination of alcohol and marijuana may be dangerous, even if the consumption is at legal levels for blood alcohol content. More research is necessary to determine how the risk increases as heavy or binge drinking is introduced.