Despite the growing interest in the prodromes of psychosis, the proper identification of those Ultra High Risk (UHR) subjects who will convert to psychosis remains an unresolved issue. It remains to be fully understood whether the risk of transition to psychosis is incremented by the concomitant presence of non-psychotic symptoms. We performed a systematic review in order to estimate: prevalence rates of non-psychotic disorders in UHR individuals and whether any comorbid disorder impacts on the risk of transition to frank psychosis. The review was conducted using the PRISMA guidelines by searching PubMed until August 2017. The inclusion criteria were: studies with appropriate definition of UHR/ ARMS (At Risk Mental States for psychosis); cross-sectional design (for prevalence rates) or longitudinal design (for transition rates to psychosis); adolescents and/or adults; specified instrument/interview for the diagnosis of mental disorder/symptoms. We included 46 English-language articles. We found that non-psychotic symptoms are a prevalent concern in UHR individuals, and this is true for all comorbid disorders examined. None of the mental disorder examined appear to be a marker for transition to psychosis. Our systematic review found that the great majority of UHR individuals actually has a highly prevalent clearly defined, above-the-threshold mental disorder that should constitute the primary focus of intervention.
