Xenu, with the help of Psychiatrists posing as tax inspectors, injected these citizens with drugs to render them unconscious and trapped them in blocks of ice where they were transported on Xenu's space cruisers (which look like DC-8s with rocket engines) to Teegeeack (Earth). While on Teegeeack, the aliens were assembled in their ice prisons and destroyed utterly with hydrogen bombs (ten times more powerful than the ones today).
The souls of these aliens ascended up through the universe but Xenu was ready for this - he had gigantic machines in the air ready to run electric current through their souls and cluster them. Xenu then had the souls packaged and sent to implant stations (movie theaters) where they were forced to watch 36 days of material ranging from God, the Devil (and ironically Space Opera too). The souls were then unleashed on TeeGeeack where they attached themselves to every living thing and to this day, they are the source of all our problems and our misery.
It was around this time that loyal officers (to the people apparently) attacked Xenu on Earth and over the course of six years Xenu was defeated with many of his henchmen. You will later find out that most of Xenu's dead companions are ALSO thetans and are clustered into evil thetan clusters (but that's later in OT7/OT8!). Xenu and his officers were then imprisoned in the center of a huge mountain on Earth never to be released again (even though he's alive ...)
So there you have it, you're not bi-polar, depressed or schizophrenic you're just suffering from the fall out of an intergalactic genocide 75,000,000 years ago.
Hubbard talking about it all ...