the phrase "a bit of shock therapy" is used by amy to explain to adam that he should not think of her a something special. why is this incident important?

This phrase is one of the clues that point toward the novel's climax. At this point in the story, we aren't sure exactly what she means, but we can assume that it is in some way meant to be ironical, in that he's in the hospital speaking to some type of therapist.