I think the premise is the mouse studies made on the subject, for example: "Young Blood Rejuvenates the Aging Brain" > Previous studies have demonstrated that

I think the premise is the mouse studies made on the subject, for example: "Young Blood Rejuvenates the Aging Brain" > Previous studies have demonstrated that instilling young blood into an old rodent can rejuvenate peripheral tissues, such as liver and muscle, and can stimulate the birth of new nerve cells in the brain. The authors show that this method can also counteract age-related declines in learning and memory by activating specific signaling pathways in the hippocampus, a region of the brain involved in learning [..] > These experiments raise the fascinating possibility that transfusion of blood or specific bloodborne factors from young humans might rejuvenate the aged human brain. http://stm.sciencemag.org/content/6/238/238ec95 http://stm.sciencemag.org/content/6/238/238ec95