For their study, researchers looked at almost 80,000 motorcycle drivers and nearly 6,000 passengers who were involved in crashes between 2007 and 2010. They found that roughly two-thirds of the drivers were wearing helmets at the time of their crash, compared to only 57.2 percent of passengers.
They study also determined that traumatic brain injuries were the most common type of injury for both drivers and passengers, but passengers were found to experience such injuries in 40 percent of cases, compared to 36 percent in cases for drivers.
While the increased rate of traumatic brain injuries among passengers would at first seem to be the result of lower helmet use, researchers found that the increased rate of brain injuries remained among when helmets were involved.
In fact, the rate of traumatic brain injury among helmeted passengers was 36 percent, the same as unhelmeted drivers, while the rate of traumatic brain injury among helmeted drivers was reduced to 31 percent.
Dr. Tyler Evans of the Indiana University School of Medicine in Indianapolis believes the increased rate of traumatic brain injuries among passengers could be due to an increased risk of ejection from the motorcycle in certain accidents.
He added that in motorcycle crashes that occur at a high rate of speed, the impact may be so severe that a helmet simply cannot protect its wearer.
Evans also opined that drivers may benefit from sitting behind a protective windshield with a firm grip on the steering column, providing increased stability over passengers who often sit at a higher position with little to hold on to.
As somewhat of a side observation, researchers noted that alcohol was associated with decreased use of helmets. Fewer than half of passengers and drivers determined to be under the influence of alcohol at the time of their collision wore helmets, with rates of 42 percent and 49 percent, respectively.