That's funny, I had the almost same sci-fi scenario thoughts during one night. The thought of the nature of our minds being defined by a disease that we caught at some point in time and now completely identify with it, that that disease made us forget our true nature. It's pretty great as a sci-fi scenario, but I now believe it has a deep truth to it.

I later discovered the writings of Eckhart Tolle. According to him, we are diseased in the sense that we identify with our mind/ego, instead of realizing what it actually is: a tool. Part of the problem is we often don't know what exists underneath. We are 100% convinced we are our mind. But obviously we're not - if we were, we wouldn't be able to observe it. Once we realize we're not our mind, we're free of its control. Until we do, we're in a way, severely ill. We're actually not disfunctional in our true nature - but we're unenlightened.

At least that's what Eckhart Tolle says. I personally find it disarmingly logical - and reasonably easily provable within my perception, not to mention deeply liberating/changing. Finding out you can stop your thoughts and not only still be aware, but become the most aware you can be, that's quite a doozy of a realization.