Current research is being done to answer this question, and there are several clinics around the world devoted to identifying and helping "at risk" individuals. It does appear that the onset of schizophrenia can be triggered by stress or by using certain drugs such as marijuana. If a person has a family history of schizophrenia, avoiding illicit drug use is advisable, as well as reducing stress, getting adequate sleep and starting antipsychotic medications as soon as necessary.