Vampires knew it all along, but now scientists have discovered that young blood can keep an old brain sharp. Plasma or blood from a young mouse — or even a single protein from plasma — rejuvenates sluggish bodies and minds in a host of ways, three new studies find. Throughout the ages, people have searched far and wide for an elixir that replenishes the body. “Maybe they were just looking too far, ” says Tony Wyss - Coray of Stanford University School of Medicine, coauthor of a May 4 study inNature Medicine. Young blood recharges old neurons, improving mice’s ability to learn and remember things, Wyss - Coray and colleagues found. Two other papers, appearing May 4 inScience, identified a particular ingredient in young blood that improves both brain and muscles.