I hate to be the person who always asks about such messed up things but my stories are full of them. Anyways, I'm doing some research for my current story and I kinda wonder what can make someone mad to the point they don't know who they are. I'm talking about a sane reasonable person who loses all perception of reality and adopts a whole new personality. I know that it might happen due to some traumatic experiences but I'd like to get more detail on that. Can anyone elaborate or give examples?
I would suggest referencing the book Sybil. She had 16 distinct personalities all created through years of physical and mental abuse. Sybil is a 1973 book by Flora Rheta Schreiber about the treatment of Sybil Dorsett (a pseudonym for Shirley Ardell Mason) for dissociative identity disorder (then referred to as multiple personality disorder) by her psychoanalyst, Cornelia B. Wilbur.
Usually a person snaps after being under extreme stress. The last straw that breaks the camel's back can be anything from a traumatic event such as the death of a loved one to too much work piling up in the workplace. A lot of it can depend on the person and the circumstances involved.
I'm willing to say repetition and stress. Even the most sane person is going to get stressed occasionally, and it could be something entirely mutually exclusive and coincidental from the plot even, which is a good thing (IMO). Once the obligatory stress has begun, bring in the repetition; people asking him where something is, or what he did with something, et cetera. Finally, have something like the question that is usually asked of him be asked of someone else. He can turn around, have an outburst, and people can just be like, "Dude... wasn't talking to you. Calm down." That sort of thing really pisses people off.
What you're referring to is called a dissociative fugue, where one who is usually sane suddenly adopts a new identity and travels away from home. This can happen to anyone, but it is a relatively rare disorder. About 0.1% of people have suffered from it, I think. This is all from memory, I don't really remember the statistics, but I remember thatthere is a very small chance of anyone getting it. This disorder is fueled by high, continued stress. For example, a teenaged boy who is constantly being bullied at school will one day, quite suddenly, travel away from his home and create a new life for himself. It is believed that Agatha Christie had once suffered from it when she was found in a hotel with no clue as to how she got there. Then again, that could be a case of dissociative amnesia. When one is having the dissociative fugue, he doesn't know of his past life. It's very possible for this person to "wake up" and never have this disorder again. No one really knows how this works. It just does. If you're interested, you should probably look into the DSM-IV.
An illness. Illness can work in multiple ways. It has the capacity to enlighten someone, but it also can drive him mad. The constant stress of being debilitated or held back can cause sadness and depression. The fear of dying also can create similar emotions.
I wouldn't really associate that sort of thing with illness. Injury or disability would, but I seriously doubt the ability of simple illness to do that. Serious diseases like cancerous growths and such things may, perhaps, but most illnesses I doubt would do that. I mean, my hands are the tools of my trade and my feet are the tools of my freedom. I couldn't stand losing my ability to run; I hate that kind of confinement. And I couldn't stand having to learn to type one-handed. Leatherworth does have an extremely fine point, but I wouldn't say that illness is exactly right.
An inability to change something that they are obsessed over. Could be anything from a ringing in their ear or a leaky water faucet, to a "Big Brother" type of thing they are constantly fighting.
... When the OP said sane, I think they mean, like, a really ordinary sane person. I might be wrong, but "Big Brother" types of things don't seem anywhere near sane, haha.
Your right. Though when I think illness, I think debilitation and trauma. I don't mean a simple head cold. So, to rephrase, I should say serious illness or chronic illness; maybe cancer would suffice. Something that one has no control over.
being the victim of a violent crime, or a sudden catastophic disaster like being trapped in an earthquake or tornado collapse, or train wreck, seeing dead and injured all around him/her, etc....
Anything that someone is exposed to that is completely mind-blowing can lead to them developing multiple personality disorder. Basically it's a defense mechanism where your mind invents a new personality to protect your true personality from the unreasonable amounts of stress that such an event could cause. People who are unstable mentally are even more prone to this i believe.
So is it possible that the old persona would be destroyed in the process or would the personality just split?
Being held as a prisoner of war with no connection to the outside world for an indefinite period of time.
I don't think it would be completely gone. However they could forget about it entirely (amnesia) or perhaps they could be aware of it but not know how to get it back / access it. I believe that the personalities spawn from MPD can be quite numerous, but I don't know much (if anything) about what would cause each different one to surface.
