I have now finished Travels in Siberia by Ian Frazier http://us.macmillan.com/travelsinsiberia. One of the author's recurrent themes was paranoia. When he would get discouraged, disheartened, or just really tired, he would get paranoid. Initially, when he was travelling in Russia, his command of the language was minimal, so he was left out of a lot of what was happening around him, including what his own fate would be, unless he was with English speaking Russians (and, the truth be known, there are quite a few.) But he often expressed that he became suspicious and paranoid, not knowing what the plans were and what would happen next.
For much of his journeys, he had a guide, who came well recommended by someone he trusted, and who was in his employ, but seemed to be a little high-handed at times, and did not include him in everything that was transpiring. It was probably for the best. I suspect sometimes things were done colloquially and not by the book. And, one of the reasons he hired the guide, was to do just that. But, he had suspicions of the man's character. Additionally there were long periods of being confined with him, and his helper, in an often unreliable vehicle that the guide procured, as they travelled across Siberia. My suspicion was that the vehicle was as good as it would get, anyway. But it was not trust and faith inspiring. So, this contributed to the paranoia.
I work in a psychiatric prison, and sometimes, our patients experience paranoia based on basically the same thing. They may not be English speaking. Or, they may be so naive and unaware of the prison culture, that they simply have no concept of what is occurring around them, and how people in prison are inclined to lie, extort, take advantage, and in general dominate others any way they can.
I never thought about it, but I can understand how this would contribute to paranoia, and I would be susceptible to such paranoia in those circumstances.