Symptoms of psychosis are triggered by a traumatic event or extremely stressful life events (e.g. – death of loved one, traumatic accident). While symptoms are severe, the person usually recovers in a short span of time (Chabrol, 2003).

Schizophrenia

When the symptoms of psychosis have been present for a period of more than six months. Other symptoms experienced include diminished motivation, social withdrawal, reduced interaction and communication, impaired concentration, and diminished insight into being unwell (Brown, 2012).
http://www.techizo.com/brief-reactive-psychosis/
http://www.techizo.com/introduction-psychosis/