The first thing to understand is that psychosis is not one thing. It is multi-dimensional in description and it has multiple causes. Frequently the cause is a severe mental illness such as schizophrenia, bi-polar disorder, major depression, delusional disorder, as well as being a transient symptom of a variety of personality disorders. For example this piece if from my life experience, and due to this experience I am the man that you see standing in front of you on a daily basis.