Get ready for a (literally) breathtaking trek up Mt. Everest, from Base Camp at 17,600 feet; through the chilling, corpse-strewn Death Zone; to the very pinnacle of the the Earth, five and a half miles above sea level. For those brave souls who survive the harrowing climb to the top of the world, it is a transformative experience. But can the excruciating ascent—through frigid cold, blasting wind, blinding sun, and severe lack of oxygen—cause permanent, damaging changes to the human brain and bo...