From Mother Jones:
Experiments on mice have shown that it is possible to rejuvenate the brains of old animals by injecting them with blood from the young. [Saul Villeda], who led the work, found that blood from young mice reversed some of the effects of ageing in the older mice..."Do I think that giving young blood could have an effect on a human? I'm thinking more and more that it might," said Villeda.I was sure this was the plot of a Mystery Science Theater 3000 movie with Tor Johnson, but I was wrong.
It was Bela Lugosi!