For centuries, the vanished Inca fortress of Ancocagua existed only in lore. Now, at a mountaintop site in Peru, researchers are zeroing in on a discovery that could reshape what we know of the empire’s last days.

Neuropsychologist Martin Teicher reveals the alarming connections scientists are discovering between child abuse—even when it is psychological, not physical—and permanent debilitating changes in the brain that may lead to psychiatric problems.