I've questioned this too! The lines get blurred at times, between extreme anxiety vs. paranoia and/or delusions. There have been times I've had some paranoid delusions, where I have some awareness that it's likely my mind playing tricks on me. During those times, I seek out many people close to me for reassurance that what I'm thinking isn't real. For a couple of seconds I will believe them, or I'll have some idea that my thoughts are really exaggerated. The bad part is, shortly after receiving that reassurance, I'll go back to my original, paranoid belief system.