Study about addiction to placebo I was wondering if anyone knows about a study where people were given a placebo, then told over and over that it was addictive and would have terrible trouble coming off of it. It would be nice if these studies involved a brain scan as well.

I don't want to complicate this post, so I won't give my reason for asking this, but if you're interested I'll add it to the comments.
I'm not aware of a more systematic study, but I'm aware of some (old) case reports, best summarized in this 1978 1-para letter-to-the editor (of AJP):


  SIR: I would like to comment on the interesting paper ‘‘A
  Note on the Addictive Personality: Addiction to Placebos”
  by Ira Mintz, M.D. (March 1977 issue). Dependence on placebo
  might not be rare. As far as I know, I published the first
  case report nine years ago (1). Similar descriptions by Czech
  authors followed (2, 3). Dr. Mintz’ patients and my patient
  were schizophrenic, but the other patients never have been
  psychotic.
  
  REFERENCES
  
  
  Vinar O: Dependence on a placebo: a case report. Br J Psychiatry
  115:1189-1190, 1969
  Boleloucky Z: A contribution to the problem of placebo dependence:
  case report. Activ Nerv Super(Prague) 13:190-191, 1971
  Honzak R, Horackova E, Culik A: Our experience with the
  effect of placebo in some functional and psychosomatic disorders.
  Activ Nerv Super(Prague) 14:184-185. 1972