Psychotic-like experiences (PLEs) in the general population of Hong Kong

Abstract

 Psychotic symptoms do not occur exclusively in individuals with psychotic disorders, but are commonly reported by persons in the general public. Researchers have argued that these psychotic-like experiences (PLEs) are subclinical manifestations of positive psychotic symptoms occurring in the general population. It has been proposed that psychotic-like experiences and clinical psychosis exist on the same continuum, where clinical cases are the minority, and the majority of the psychosis phenotype is made up of PLEs experienced by individuals in the general population. The study of psychotic-like experiences could potentially help us to understand the course of development of psychosis. The current work presents a baseline study who explores prevalence of PLEs and associated factors in an epidemiological study (Hong Kong Mental Morbidity Survey 2010, HKMMS) and a prospective case-control follow-up study that explores the longitudinal trajectories and predictors of PLEs in the general population of Hong Kong. 174 out of 5719 subjects with PLEs and without a diagnosis of psychotic disorders were identified through the baseline epidemiological study. A control group of the same number was matched on age, gender and years of education. Both groups were assessed for psychotic-like experiences and psychotic symptoms, socio-demographic information, family history of psychiatric disorder, history and diagnosis of psychiatric disorder, stressful life events, physical illness, social and occupational functioning and neurocognitive functions. Results showed that the one-year prevalence of PLEs in the general population of Hong Kong is 3.01% while the two-year incidence was 3.51%. 47.15% who reported PLEs had persistent PLEs at 2-year follow-up, where one subject in the experimental group fulfilled high-risk criteria for psychosis and one developed clinical psychosis. Also, some control subjects reported PLEs at follow-up; the two-year incident rate of PLEs was found to be 3.51%. Overall, subjects with PLEs had more psychiatric morbidity and symptoms when compared with controls at baseline. Subjects with PLEs also had poorer social and occupational functioning, higher suicidal ideation, experienced more stressful life events and had more family history of psychiatric disorders at baseline. It was also found that female gender, having a religious belief, having history or current psychiatric disorders as well as not reporting paranoia PLEs at baseline significantly predicts the persistence of PLEs at follow-up. Subjects with persistent PLEs showed various improvements in health and functioning factors as well as social environmental factors at follow-up; however, substantial cross-sectional differences in mood symptoms and neurocognitive functions were still observable betewen subjects with and without perisstent PLEs. Regarding neurocognitive function, subjects with PLEs had poorer performance in processing speed, executive functioning and attention when compared with controls. Although some characteristics of PLEs mirrored those found in clinical psychosis, our results found that PLEs were heavily affected by psychiatric symptoms and disorders, suggesting that PLEs could be a transdiagnostic indicator of functional impairment and psychiatric morbidity. Qualitative analyses were also carried out to explore the characteristics of the PLE phenomena and some differences of subjective appraisals were found between persist and non-persist beliefs of PLEs. The is the first study to report the longitudinal trajectories and explore the qualitative characteristics of PLEs from non-psychotic subjects in a general Chinese population. Results of PLEs’ characteristics, distributions and associated factors could fill the existing knowledge gaps of the epidemiology of PLEs in a Chinese population. Future research may examine subjects with PLEs but without psychiatric morbidities to delineate the implications of PLEs and its persistence in a healthy population.