This is an actual scientific study involving brain scans. It shows atrophy of grey matter as well as white matter abnormalities:
http://www.plosone.org/article/info:doi%2F10.1371%2Fjournal.pone.0020708 Damn. Better kill it before it kills you.
Short attention span infographic on a related subject:
http://www.techi.com/2012/06/your-internet-may-be-hurting-your-brain/