I'm no expert, but my stupid opinion is that most of the stuff dealing with solitary confinement overemphasizes (including the referenced article) the role of human need for social interaction and underemphasizes the simple fact that boredom is torture. A life in solitary with a reasonable supply of entertainment (books, tv, "nonsocial" internet, a pad and pencil to doodle with) that still left somebody basically socially isolated would, I think, sustain people psychologically a hell of a lot longer than being in "the hole" with no stimulus whatsoever.
That's not to say that the social isolation is no big thing, and I think it's clear from the article that social isolation over the long term is quite damaging, but really I think it's the boredom that can drive people insane rather quickly.
