Prevalence of At-risk Criteria of Psychosis in Children and Adolescents, and in Young Adults: Results From Two Swiss Community Samples

Abstract

The prevalence and significance of APS and other risk symptoms in the general population, when assessed in the same way as in help-seeking persons, is still rather unclear. In two complimentary studies, we studied the prevalence of ultra-high risk and basic symptom criteria and symptoms assessed with the ‘Structured Interview for Psychosis-Risk Syndromes’ (SIPS) and the ‘Schizophrenia Proneness Instrument, Adult / Child and Youth version’ (SPI-A/SPI-CY) by trained psychologists in random community samples of age 8-17 and 16-40 years. At the time of writing, 1229 interviews with young adults and 55 with children/adolescents were completed. While only 2.8% of the young adults acknowledged the presence of any risk criterion, 9.1% of the children/adolescents did so. An even more pronounced age-related difference was found in the prevalence of lifetime risk phenomena: 25.2% of the young adults and 45.5% of the children/adolescents reported at least any one. Thereby, 'perceptual abnormalities/hallucinations” of the SIPS, mainly on APS level, were most frequent in both samples. While risk phenomena occurred, at least temporarily, in a quarter of young adults and even in nearly half of the children and adolescents, only a minority fulfilled the frequency and onset requirements of SIPS and SPI-A/SPI-CY – again with higher rates in children and adolescents. This highlights the importance of these additional requirements of the risk criteria, but also the need to further examine developmental peculiarities. These factors might play a crucial role in the differentiation between ill and non-ill persons and thus should be studied in more detail.