A WALL STREET JOURNAL TOP 10 BOOK OF 2025 ALSO NAMED A BEST BOOK OF 2025 BY THE NEW YORKER AND THE NEW YORK PUBLIC LIBRARY "Valley of Forgetting reminds us that scientific progress is measured not only in breakthroughs but also through the sacrifices people make, the trust that is built. It is a tender story of the unshakable will to make meaning in the face of inexorable loss. . . . Smith elegantly captures what it means to love, to belong, to hold on to one another when so much is uncertain." --Washington Post The riveting account of a community from the remote mountains of Colombia whose rare and fatal genetic mutation is unlocking the secrets of Alzheimer's diseaseIn the 1980s, a neurologist named Francisco Lopera traveled on horseback into the mountains seeking families with symptoms of dementia. For centuries, residents of certain villages near Medellín had suffered memory loss as they reached middle age, going on to die in their fifties. Lopera discovered that a unique genetic mutation was causing their rare hereditary form of early onset Alzheimer's disease. Over the next forty years of working with the "paisa mutation" kindred, he went on to build a world-class research program in a region beset by violence and poverty. In Valley of Forgetting, Jennie Erin Smith brings readers into the clinic, the laboratories, and the Medellín trial center where Lopera's patients receive an experimental drug to see if Alzheimer's can be averted. She chronicles the lives of people who care for sick parents, spouses, and siblings, all while struggling to keep their own dreams afloat. These Colombian families have donated hundreds of their loved ones' brains to science and subjected themselves to invasive testing to help uncover how Alzheimer's develops and whether it can be stopped. Findings from this unprecedented effort could hold the key to understanding and treating the disease, though it is unclear what, if anything, the families will receive in return. Smith's immersive storytelling brings this complex drama to life, inviting readers on a scientific journey that is as deeply moving as it is engrossing.