Subclinical psychosis syndromes in the general population: results from a large-scale epidemiological survey among residents of the canton of Zurich, Switzerland

Abstract

Aims. Prevalence and covariates of subclinical psychosis have gained increased interest in the context of early identification and treatment of persons at risk for psychosis. Methods. We analysed 9829 adults representative of the general population within the canton of Zurich, Switzerland. Two psychosis syndromes, derived from the SCL-90-R, were applied: 'schizotypal signs' and 'schizophrenia nuclear symptoms'. Results. Only a few subjects (13.2%) reported no schizotypal signs. While 33.2% of subjects indicated mild signs, only a small proportion (3.7%) reported severe signs. A very common outcome was no 'schizophrenia nuclear symptoms' (70.6%). Although 13.5% of the participants reported mild symptoms, severe nuclear symptoms were very rare (0.5%). Because these two syndromes were only moderately correlated (r = 0.43), we were able to establish sufficiently distinct symptom clusters. Schizotypal signs were more closely connected to distress than was schizophrenia nuclear symptoms, even though their distribution types were similar. Both syndromes were associated with several covariates, such as alcohol and tobacco use, being unmarried, low education level, psychopathological distress and low subjective well-being. Conclusions. Subclinical psychosis symptoms are quite frequent in the general population but, for the most part, are not very pronounced. In particular, our data support the notion of a continuous Wald distribution of psychotic symptoms in the general population. Our findings have enabled us to confirm the usefulness of these syndromes as previously assessed in other independent community samples. Both can appropriately be associated with well-known risk factors of schizophrenia.

The validity of the Schizotypal Personality Questionnaire in a Greek sample: Tests of measurement invariance and latent mean differences

“…Schizotypal traits are present in the general population [1] and are distributed along a continuum, psychosis occupying its extremity [2]. Johns and van Os [3] proposed that schizotypy is a rather quantitative trait that ranges from normality at one end of the psychosis spectrum through different compositions of schizotypal traits to psychosis at the other end, thus highlighting the dimensionality of schizotypal traits.…”

Brain correlates of verbal fluency in subthreshold psychosis assessed by functional near-infrared spectroscopy

“…Subthreshold psychotic symptoms can be identified with standardized scales (e.g., Rössler et al, 2007Rössler et al, , 2013, providing an index of psychosis proneness. A high score of psychosis proneness has been reported to represent a 10% increased risk to develop a schizophreniaspectrum disorder (Chapman et al, 1994;Hanssen et al, 2005;Meehl, 1990).…”

Association between processing speed and subclinical psychotic symptoms in the general population: Focusing on sex differences

“…It influences not only their behavior and feelings but also their cognitive abilities. Reduced cognitive abilities are also phenotypically represented as "thought disorder" in persons with sub-clinical psychosis (Rössler et al, 2013c). Although most psychosis symptoms are transient and episodic in nature, the variability in their expression is predominantly caused by stable traits (Rössler et al, 2013b).…”