There might be something to those vampire legends: a creepy new experiment has shown that, when infused with the blood of younger mice, older mice grow more nerve cells in their brains and become more adroit at navigating maze environments.
"It was as if these old brains were recharged by young blood," said Tony Wyss-Coray, PhD, the senior author of the study appearing in Nature Medicine and a professor of neurology and neurological sciences at Stanford University School of Medicine.
The researchers argue if the same goes for humans, the findings could be a boon to new approaches to treating the effects of dementia such as Alzheimer's disease.
Wyss-Coray and colleagues paid particular attention to the hippocampus -- the region of the brain that is critical for forming certain types of memories, particularly memories involving spatial patterns. As Wyss-Coray explained in a press release, you use your hippocampus when, for example, "try to find your car in a parking lot or navigate around a city without using your GPS system."
Studies have shown that the hippocampus is very responsive to experience and becomes larger as you file away more information. The region, however, is also sensitive to aging. It is among the areas of the brain that shows most deterioration in patients with dementia.
After infusing older mice with plasma from the blood of younger mice, the cells in these brain regions of the older mice came back to life. Hippocampal nerve cells from the older mice became better at strengthening the connections between one nerve cell and another - essential to learning and memory.
Their behavior also showed signs of improvement. In a test in which the mice were trained to quickly locate a submerged platform in a water-filled container, the older mice became faster after the plasma infusions. (The study also showed the reverse is true -- infusing younger mice with the blood of older mice hindered the younger mice's ability to grow more nerve cells and hindered their navigation skills).
"There are factors present in blood from young mice that can recharge an old mouse's brain so that it functions more like a younger one," Wyss-Coray said in a press release. "We're working intensively to find out what those factors might be and from exactly which tissues they originate."
Could the same trick work in humans? The Stanford University Medical School is already working on finding out. The group has started a company that is planning a small clinical trial that would give Alzheimer's patients a series of injections of plasma from young donors.
Other researchers caution while the findings are exciting, they remain preliminary.
"The therapeutic implications are profound if this mechanism holds true in people," Matthew Kaeberlein, a biologist who studies aging at the University of Washington, Seattle told Science Now. But, he added, that "is the million dollar question here, and that may take some time to figure out."