Can chronic stress cause schizophrenia?
This is a very interesting question.
Chronic stress may lead to psychotic symptoms (hallucinations, delusions), either in the context of post-traumatic stress disorder or depression. In these conditions, when psychosis is present, there are abnormalities in the hypothalamic-pituitary-adrenal (HPA) "stress" axis.
As for schizophrenia, stress (life events) seems to be associated with the worsening or relapse of psychotic symptoms. This is like all kinds of medical conditions, where stress often seems to make symptoms worse.
Schizophrenia however is not just psychotic symptoms. It also includes problems in thinking (concentration, planning, memory, etc.) as well as what are called "negative" symptoms (low motivation, difficulty enjoying things, lack of strong feelings, little emotional expression). Schizophrenia can also include odd and disorganized thinking and behavior.
There doesn't seem to be evidence that stress leads to these other symptoms in schizophrenia.
It is interesting that childhood trauma is more common among patients with schizophrenia than for individuals without this illness. However, whether the trauma causes the schizophrenia though, at least for some people, is not clear.