A lot of this has to do with the fact that the human brain and its workings remain as mysterious to us as the deep ocean blue. Doctors have been studying the brains of syphillitics, insomniacs, manic-depressives, serial killers, and even "normal" people, for a long time. Progress has certainly been made as far as understanding many, many things that we formerly were pretty clueless about, but it seems that every new discovery brings with it a massive revision of what we thought we knew twenty years ago... or even five years ago.
Madness and creativity have been good friends for a long time, something that anyone who has read more than a few paragraphs about some of the greats can tell you. But when I started digging around in the modern parameters for establishing schizophrenia, I became a little... well, I'll go ahead and use the word paranoid.
Because doctors have no way of documenting the internal processes of the insane, they have to rely on external behaviors to diagnose schizophrenia. Here's a general list of symptoms from the Mayo Clinic:
- Delusions: These beliefs are not based in reality and usually involve misinterpretation of perception or experience. They are the most common of schizophrenic symptoms.
- Hallucinations: These usually involve seeing or hearing things that don't exist, although hallucinations can be in any of the senses. Hearing voices is the most common hallucination among people with schizophrenia.
- Thought Disorder: Difficulty speaking and organizing thoughts may result in stopping speech midsentence or putting together meaningless words, sometimes known as word salad.
- Disorganized Behavior: This may show in a number of ways, ranging from childlike silliness to unpredictable agitation.
- Loss of interest in everyday activities
- Appearing to lack emotion
- Reduced ability to plan or carry out activities
- Neglect of personal hygiene
- Social withdrawal
- Loss of motivation
Yep. I dare any writer lost in the drafting process to look at these lists and defiantly declare they exhibit zero of these symptoms.
Now, be assured I'm not making light of mental illnesses. I've been doing some heavy research and learning a lot about the diagnosis (and mis-diagnosis) of mental illnesses both in the past, and not-so-distant years. There have been plenty of people institutionalized that were less outwardly insane than you or I. On the flip-side, some people who really need help don't get it because their symptoms aren't extreme enough to warrant intervention.
In the end, the most glaring fact I've taken away from my research so far (and please, be aware that I know exactly how much of a layman I am) is that we really don't understand the human brain very well, even today.
If I've piqued your interest check out this recent TEDtalk about what we know - and what we don't.