Abreaction is a psychoanalytical term for reliving an experience in order to purge it of its emotional excesses; a type of catharsis. Sometimes it is a method of becoming conscious of repressed traumatic events.
Early in his career, psychoanalyst Carl Jung expressed interest in abreaction, or what he referred to as "trauma theory", but later found it had limitations concerning the treatment of neurosis. Jung stated that: "though traumata of clearly aetiological significance were occasionally present, the majority of them appeared very improbable. Many traumata were so unimportant, even so normal, that they could be regarded at most as a pretext for the neurosis. But what especially aroused my criticism was the fact that not a few traumata were simply inventions of fantasy and had never happened at all".
Emphasis added above. The real problem with Dianetic therapy (apart from the fact that the E-meter is bullshit) is that the "pre-clear" (subject) is specifically told that any thought pictures which come into their mind during the therapy are "real for them". There is no attempt to distinguish something that actually happened from something they made up. It is absolutely unsurprising at that point that Dianetic patients started "remembering" insane shit from past lives in "space-opera" civilisations. I believe that Hubbard did this to himself. Through misuse of a reasonably valid psychic process (which he knocked off from Crowley via Jack Parsons) he actually started believing, for example, that he could remember his mother engramming him up by badmouthing him in the womb, or attempting to abort him with knitting needles. Eventually, it seems he quite serionsly believed in Xenu.
The sad thing is that even the "Freezone" Scientologists, some of whom are good, sincere people, have convinced themselves of cosmologies which look very much like schizophrenic ravings, because they started treating weird things they saw in their mind as real - just as Elron told them too. Case in point: one of the more famous Freezoners teaches in his "Scientology 101" book to reconstruct past lives by just making something up and then assuming that it's true. Witness where this leads - the same writer's advanced textbook contains a cosmology which reads like a combination of schizophrenic fugue and childhood nightmares. It's worth reading for the sheer "WTF?" factor - that someone who appears to be a calm, rational and pleasant person has programmed himself into believing this stuff. (A representative sample.)
In short: Dianetics and thence Scientology implants its practitioners, by repetition, with a solipsistic worldview, where images in the head are always real. If you take it far enough you do end up in a schizophrenic-style cosmology, where increasingly bizarre images are run together in a pattern which doesn't make any real-world sense. This reminds me of that scene in Voyage of the Dawn Treader with "the land where dreams come true". Not somewhere I'd want to go.
Perhaps the greatest irony is that perhaps mainstream Scientology actually *protects* its poor enslaved dupes from total insanity, by imposing an exterior limit on where someone's "research" into crazy internal universes can go. The Freezoners have no limit and often end up in places which make the Xenu story look plausible. This would of course explain why the Freezone is so schismatic - on one hand each individual is doing "research" into completely fraudulent internal universes, while on the other hand pretending to be part of a community of scientific researchers seeking reproducible results. Of course no two schizoid delusions are going to be congruent.
Hey, there's a political message in that - solipsism, and other "ideas are real" thought systems, lead to either total anarchic fragmentation of the community, or imposition from above of a True Way. No place for democracy and collective reality-tunnel-formation except in a materialist thoughtsystem.
One point where I believe UCP has kicked off its Scieno heritage is that it asks you to imagine things that *might* be real, rather than telling you they necessarily are. It probably won't cure false memories but it shouldn't impose any that weren't already there.