The distribution of positive psychosis-like symptoms in the population: A latent class analysis of the National Comorbidity Survey
Received 7 June 2006; received in revised form 7 August 2006; accepted 15 September 2006. published online 13 November 2006.
Abstract
Objective
Previous research has suggested that psychosis is better described as a continuum rather than a dichotomous entity. This study aimed to describe the distribution of positive psychosis-like symptoms in the general population by means of latent class analysis.
Method
Latent class analysis was used to identify homogeneous sub-types of psychosis-like experiences. Multinomial logistic regression models were used to interpret the nature of the latent classes, or groups, by estimating the associations with demographic factors, clinical variables, and experiences of traumatic events.
Results
The best fitting latent class model was a four-class solution: a psychosis class, a hallucinatory class, an intermediate class, and a normative class. The associations between the latent classes and the demographic risk factors, clinical variables, and experiences of traumatic events showed significantly higher risks for the psychosis class, the hallucinatory class, and the intermediate class compared to the normative class. Furthermore there appeared to be a grading in the magnitude of the odds ratios: the odds ratios for the psychosis group were generally higher than those for the hallucinatory class, and the odds ratios for the hallucinatory class were generally higher than those for the intermediate class.
Conclusions
The latent class analysis showed that psychosis-like symptoms at the population level could be best explained by four groups that appeared to represent an underlying continuum.
aPsychiatric Epidemiology Research Unit, University of Ulster at Magee College, UK
bThe Trauma Resource Centre, North and West Belfast HSS Trust, UK
cSchool of Psychology, The Queen's University of Belfast, UK
Corresponding author. School of Psychology, Faculty of Life and Health Sciences, University of Ulster at Magee Campus, L'Derry, BT48 7JL, Northern Ireland, UK. Tel.: +44 28 71 375619.
ABSTRACT