'A rose is a rose is a rose', but at-risk criteria differ.

BACKGROUND: Over the last 15 years, efforts to detect psychoses early in their prodromal states have greatly progressed; meanwhile, ultra-high risk (UHR) criteria have been the subject of such consensus that parts of them have been proposed for inclusion in DSM-5 in terms of an attenuated psychosis syndrome. However, it is frequently unacknowledged that the definitions and operationalizations of UHR-related at-risk criteria, including the relevant attenuated psychotic symptoms, vary considerably across centers and time and, thus, between prediction studies. METHODS: These variations in UHR criteria are described and discussed with reference to the rates of transition to psychosis, their prevalence in the general population and the proposed new operationalization of the attenuated psychosis syndrome. RESULTS: A comparison of samples recruited according to different UHR operationalizations reveals differences in the distribution of UHR criteria and transition rates as well as in the prevalence rates of at-risk criteria in the general population. CONCLUSION: The evidence base for the introduction of such a new syndrome is weaker than the number of studies using supposedly equal UHR criteria would at first suggest. Thus, studies comparing the effects of different (sub-)criteria not only on transition rates and outcomes but also on other important aspects, such as neurocognitive performance and brain imaging results, are necessary. Meanwhile, the preliminary attenuated psychosis syndrome in DSM-5 should not follow an altogether new definition but, rather, the currently most reliable UHR definition, which must still demonstrate its reliability and validity outside specialized psychiatric services.