In 2006 a study regarding alcohol and marijuana use among 49,000 high school age young adults revealed that of the 12th grade group, 13% smoked marijuana in automobiles and 10% drank alcohol in automobiles. The results were similar for grades 11 and 10. Studies regarding marijuana demonstrate that the impairment from smoking marijuana is equivalent to the level of impairment associated with blood alcohol levels of 0.007% to 0.10%. At that level coordination, judgment and motor control will be very impaired. The effects of marijuana last up to 24 hours with the euphoric stage lasting 6 hours. This is longer than the alcohol high. The individuals in the study could not identify impairment associated with marijuana use beyond the euphoric state, however, they continued to have problems with coordination, judgment and motor control. In other words, they remained impaired long beyond the initial high. If they were drivers, they would be at a high risk for causing a motor vehicle accident and possibly causing a brain injury for themselves or others.
Brain injury prevention requires that we educate young adults about the effects of substance abuse. This study tells us that substance abuse occurs in motor vehicles where the risk for injury can be very high. We know that brain injury is highest among young adults, 16-24 years old. Why not be clear with our older adolescent and young adult children about the risks they face when they use drugs and alcohol. The place they choose to get high may be an additional risk factor which elevates their chance for a brain injury.
Source: Joffe, A, Journal Watch Pediatrics and Adolescent Medicine, April 11, 2007