Call me crazy, but I am not a believer in mental diseases. To me, all of these are simply people who have a view on reality that deviates from that of the masses, who are fully restricted by the "common consensus reality". As long as we remain inside that harness, we are considered "normal".
But science has now proven that it is possible for two or more realities to exists side by side for different observers, while those two realites are not reconcilable. In essence this means that rigorous proof in science becomes impossible, because both observers will think their reality to be proven true, but the two of them can never agree on their proofs.