Helmet use reduces deaths in motorcycle accidents. Motorcycle riders who generally wear helmets may be less likely to do so when they use drugs and alcohol.
A Traffic Injury Prevention study used data from the 2005-2009 Fatality Analysis Reporting System to examine the association between drug use and motorcycle helmet use. There were 9,861 fatally injured motorcycle riders in the US during this time. For fatally injured motorcycle riders, use of alcohol, marijuana, or other drugs were all linked with increased chances of not wearing a motorcycle helmet. Helmet use significantly declines among fatally injured riders mixing alcohol with marijuana and other drugs. The likelihood of helmet use between marijuana-only users and other drug users is almost the same when they have also consumed alcohol regardless of the blood alcohol level. The study controlled for the states that have no motorcycle helmet laws.