This is a scary word for most people. It means a break with reality. But basically I've found, it's a label put on people who break from their intellect or ego. I find it interesting that everyone believes in schizophrenia but very few really believe in enlightenment. Both are a break from the reality of the intellect and ego but with enlightenment one finds peace and joy from the break while in schizophrenia, one finds confusion and resentment.
So what about the people who don't break from their intellect and ego. Well here's where we have a problem because these people always end up as either masters or slaves and for the aware person, one is the same as the other because both groups are never happy. So the master tries to exploit the slave to become happier while the slave tries to get out of the slave slot and become a master. There are some cases in which the intellect and ego try so very hard to manipulate the people around them that a break occurs in the personality and an intense period of suffering begins. This condition is usually labeled schizophrenia but can also be looked at as a time of pay back for the karmic debt accrued by the person who was motivated by her intellect and ego.
Now the person who is labeled is totally cut off from relating to the world as she has in the past.The only cure for this condition is love. So you need to make someone else's happiness and well being more important than your own, and then the pain will start to be replaced by peace and joy as you learn to love without attachment.