Background: It may be possible to improve the prognosis of psychotic disorders by the timely recognition and treatment of the early stages of these disorders. Since the first psychotic episode is often preceded by a period of non-specific symptoms and functional decline, it could be worthwhile investigating whether this early phase can be detected.
Aim: To review existing diagnostic approaches and clinical instruments that are currently used for prospective identification of the prodromal phase.
Method: We searched the literature between 1995 and 2009 using the search terms 'prodromal' or 'ultra high risk' in combination with 'psychosis' or 'schizophrenia' and 'assessment'.
Results: In international literature we found four diagnostic approaches to ultra high risk of psychosis: the attenuated positive symptom approach, the basic symptom approach, the clinical high risk approach and the strictly phenomenological approach. Within each of these approaches specific screening instruments had been developed and tested with regard to their ability to correctly predict a first psychotic episode.
Conclusion: None of the current diagnostic approaches produces a sufficiently reliable prediction of the risk of a first psychotic episode. Within the group of persons assumed, based on screening, to be at very high risk, only a small percentage will actually develop a psychotic disorder.