Some people collect stamps, others vintage cars. As a young Ph.D. student at Cambridge University in the 1980s, Claude Wischik was on a mission to collect brains.

It wasn't easy. At the time, few organ banks kept entire brains. But Dr. Wischik, an Australian in his early 30s at the time, was attempting to answer a riddle still puzzling the scientific community: What causes Alzheimer's disease? To do that, Dr. Wischik needed to examine brain tissue from Alzheimer's patients soon after death. That meant getting family approvals...