Brain tissue is soft and vulnerable to physical forces.
A fall can cause the skull to deform, transferring energy to the brain. Helmets have a hard outer shell and a stiff foam liner that absorbs impact energy.
Brain injuries do not heal easily and can lead to loss of function. A study of bicyclists found that helmet use reduces the risk of brain injury by 65% to 88%.
The author's research focuses on how physical forces cause brain injury and improving helmet design.