Holo-transference dementia syndrome, or HTDS,was a medical condition in which an individual becomes overly involved in a holographic simulation and thereby begins to lose his/her sense of identity. HTDS ultimately results in the person thinking they are an actual part of the simulation.

In a delusion caused by a kinoplasmic radiation surge in 2371, The Doctor was told by Reginald Barclay that he was suffering from HTDS, that he was in fact Lewis Zimmerman, and that USS Voyager was a hologram. (VOY: "Projections")