In 1982, Dr. Francisco Lopera, a Medellin neurologist, was puzzled. A 47-year-old patient was losing his memory, and so had his father, grandfather and seven other relatives.
Other cases appeared. Dr. Lopera asked one, a 45-year-old lottery-ticket seller, to redraw portraits he had sketched years earlier, the deformed results showed already significant neurological damage.
Patients' families said this "madness" or "idiocy," called La Bobera, came from witchcraft, a tree, a Spaniard's statue, a priest angry about being burglarized.
Dr. Lopera burned to help. His grandfather had had late-onset dementia. He came from the patients' violence-scarred region, Antioquia.
And he had rough-and-tumble medical experience. When he had run a rural clinic, guerrillas made him fly to a village and ride overnight on horseback to the jungle. He fell off the horse, stranded until guerrillas noticed the empty saddle.