Characterising psychosis in the Australian National Survey of Mental Health and Wellbeing Study on Low Prevalence (psychotic) Disorders

Objective: This study examines the factorial structure of symptoms and sign s in psychosis in data from the Study on Low Prevalence (psychotic) Disorde rs which is part of the National Survey of Mental Health and Wellbeing, Aus tralia 1997-1998. Method: The present study examined a wide variety of symptoms taken from th e Schedules for Clinical Assessment in Neuropsychiatry items and the substa nce use items in the Diagnostic Interview for Psychosis, an instrument spec ially constructed for the national study. The instrument was applied to 980 community and hospital subjects with a wide range of psychotic illness dia gnoses. The data were factor analysed and scales of 'domains of psychopatho logy' derived. Results: The data were best fitted by five principal factors ('domains') wh ich can be approximately labelled dysphoria, positive symptoms, substance u se, mania and negative symptoms/incoherence. These factors together explain ed 55.4% of variance in symptoms. Solutions with more numerous factors did not improve the representation. Conclusion: The five domains successfully characterise a large part of the variance in psychopathology found in the present study of low prevalence (p sychotic) disorders. The approach allows sufferer's symptom range and sever ity to be well expressed without multiple comorbid diagnoses or the limits imposed by categorical diagnosis. Knowledge of alternative dimensional repr esentations of psychopathology may usefully complement our use of categorie s, enhance awareness of symptoms and ensure that important psychopathology is heeded in practice and research.