Susan Greenfield, an English pharmacologist, is quoted by the New York times as saying:
My fear is that these technologies are infantilizing the brain into the state of small children who are attracted by buzzing noises and bright lights, who have a small attention span and who live for the moment.
I will also cite the newspaper as saying:
Is social networking killing you? Well, no, probably not. Or at least, not literally. But two British scientists have recently suggested that spending all day, and — admit it — much of the night networking on a computer might in fact be bad for your body and your brain.
Normally, I would simply roll my eyes, but, given the origin I'd like to see some studies: Is this health threat supported by peer-reviewed studies or not?