Coasters not linked to brain injury

PHILADELPHIA, Oct. 16 (UPI) -- Although there have been a few isolated reports of people suffering brain injuries from riding roller coasters, a new mathematical model released Wednesday suggests the amusement park rides do not pose a safety hazard.

"This further demonstrates that there is no evidence of increased risk of brain trauma from riding these newer more powerful roller coasters," said Douglas Smith, a co-author of the study and a neurosurgeon at the University of Pennsylvania School of Medicine.

Smith, who usually studies head injuries resulting from automobile accidents, told United Press International there are "no studies suggesting a link that you're at an increased risk (of brain injury) from riding roller coasters." He said his model found the forces generated by roller coasters are well below levels known to induce brain injury.

Despite this, the few cases of people suffering ruptured blood vessels that caused bleeding in the brain after riding roller coasters has caught the attention of legislators. New Jersey passed a law limiting the G-forces generated by roller coasters and the U.S. Congress has proposed similar legislation. G-force is the feeling of increased weight that results from acceleration.

"I would call that (legislation) misguided," Smith said, "since you can endure higher G-forces from daily activities such as sneezing, coughing, getting slapped on the back or plopping down on the couch" than are generated by roller coasters. These activities clock in at around 6-10 Gs -- one G is equivalent to the normal force of gravity on a body at rest -- whereas roller coasters induce about 6 Gs, he said.

G-forces can induce unconsciousness by causing blood to pool in the limbs away from the brain if they last for more than 30 seconds or 40 seconds, Smith said. But the type of Gs induced by roller coasters rarely last more than 3 seconds. In addition, these forces do not cause blood vessels to rupture, just a lack of oxygen to the brain, he said.

G-forces are not the major concern, but rather head accelerations caused by sudden twists and turns on roller coasters. According to Smith's model, which is described in the October issue of the Journal of Neurotrauma, head accelerations induced by roller coasters also fall well below dangerous levels.

The model used data from three of the most powerful roller coasters -- the "Rock 'n' Roller Coaster" at the Disney-MGM Studios in Orlando, Fla.; "Speed -- The Ride" at the Nascar Café in Las Vegas and the "Face-Off" at Kings Island, Ohio -- to calculate peak head accelerations. Factoring in magnitude of force and the direction and duration of the acceleration, the model found head acceleration levels on roller coasters are "18 times less than levels known to induce injuries in brains," Smith said.

"There is nothing to suggest that there's a danger as far as head acceleration for normal individuals," Smith explained. Some of the reports of brain trauma on roller coasters noted the individuals had pre-existing conditions, such as brain aneurysms or bulging blood vessels, he said. Blood vessels in the brain can rupture even during sleep, he added, so the fact they rode a roller coaster could just have been a coincidence.

Similar levels of the head acceleration induced by roller coasters also occur during normal activities such as sneezing "so its not just roller coasters you have to be worried about," Smith said.

"A lot more attention needs to be paid to those risks we can easily identify such as rollerblading, bicycling and driving cars," he said. "To reduce the risk of brain injury, (roller coaster riders) should make sure their seat belts are buckled on the way to the amusement park."

Although Smith's model shows roller coasters do not generate amount of force known to cause brain injuries, it "does not rule out a small chance of getting (vessel rupture)," Walter Koroshetz, a neurologist at Massachusetts General Hospital, told UPI. "It's a very rare instance but there's enough evidence that there's some confluence of forces that could occur that could produce injury," he said.

Koroshetz added it is a "very low probability event and wouldn't prevent me from going on a roller coaster." People taking warfarin, a blood-thinning drug, or those who have already suffered a ruptured blood vessel in the brain, should avoid riding roller coasters, he said.

(Reported by Steve Mitchell, UPI Medical Correspondent, in Washington)