Harvard scientists have uncovered that lithium, a naturally occurring element in the brain, may be the missing piece in understanding Alzheimer’s. Their decade-long research shows that lithium depletion—caused by amyloid plaques binding to it—triggers early brain changes that lead to memory loss. By testing new lithium compounds that evade plaque capture, they reversed Alzheimer’s-like damage and restored memory in mice at doses far lower than those used in psychiatric treatments.