Schizophrenia is a serious mental illness. It is caused by the disturbances of concentration of brain neurotransmitters, changes of  receptors of the  brain cells and structural brain abnormalities rather than pure psychological reasons. Patient will have abnormal thinking, feeling, emotion, speech and behavior which affect daily life, work, social activities and the ability of taking care of oneself. Some patients are prone to attempt or commit suicide. 

You can refer to the following website.

What is Schizophrenia？

The source of information is provided by the Hospital Authority Smart Patient