Life without fear: The people who can’t feel afraid

On a bright afternoon at Disneyland in 2012, Jordy Cernik strapped himself into a rollercoaster and waited for the familiar rush of adrenaline. The clanking ascent, the plunge into speed—this was the moment his stomach should drop, his heart should pound. No sweaty palms. No jolt of panic. Just silence in his body where fear used to live. Jordy, a British man treated for Cushing’s syndrome by having his adrenal glands removed, had lost the ability to feel afraid. Later he would leap out of planes, zip-wire off Newcastle’s Tyne Bridge, and abseil down London’s Shard without so much as a quickened pulse. For him, what most people call terror is just another Tuesday. Decades earlier in Iowa, doctors met...