Evidence for the continuum-severity model of psychosis through scrutiny of the architecture of symptoms associated with schizophrenia

The psychosis continuum provides a framework to develop a compelling insight into the architecture of psychotic experiences in non-clinical samples. Using schizophrenia-specific measures within non-clinical samples offers further opportunity to investigate psychotic experiences and compare to those reported in clinical samples.A cross sectional survey method was used to collect data from a non-clinical sample (n = 510) using the Schizophrenia Quality of Life Scale-Revision 4 (SQLS-R4) and the Hospital Anxiety and Depression Scale (HADS).Conducting confirmatory factor analysis and bi-factor modelling found that a bi-factor model offered a better model fit to the data than the established two factor model. A general factor explained most item variance whilst seven domain specific factors explained a further small amount of item variance. Participants with higher anxiety reported comparatively poorer Quality of Life to those with lower anxiety. Comparison with data taken from a clinical sample found similarities in both the internal consistency and correlation coefficients between SQLS-R4 totals and sub-scales and HADS total scores and sub-scales.These results show the presence of a robust general psychosis Quality of Life factor within a non-clinical sample. The use of schizophrenia-specific measures and bi-factor modelling can provide suitable methods for investigating the nature of the psychosis continuum.