It might sound like something from a modern-day vampire movie, but transfer of youthful blood can have a reviving effect on the mind, researchers have found. Or at least, it can in mice: a study by Stanford University School of Medicine has discovered that something in the blood of young mice has the ability to restore mental capabilities in older mice. Over the course of three weeks, the scientists gave 18-month-old mice eight infusions of plasma taken from animals that were just three months old, and then put them through a set of experiments to test their spatial memory – memory relating to the position of things and how large or small they are. The mice were seen to perform consistently better in the tests after receiving the young blood. Old mice injected with the blood of other old mice, on the other hand, showed no improvement in the tests. The team found that new connections were also formed in the old mice's hippocampi, which again were not seen in the control group. The hippocampus is a brain region that plays a huge role in memory, particularly in recognising and recalling spatial patterns. It is very sensitive to ageing, showing a natural decline in function as people grow older. In conditions such as Alzheimer's disease, this deterioration is accelerated, leading to an inability to form new memories. It is as yet unclear whether transferring young blood into older individuals would have the same effect in humans.