REGIONAL HETEROGENEITY IN LIFETIME PSYCHOTIC EXPERIENCE PHENOTYPES: EVIDENCE FROM THE 2023 THAI NATIONAL MENTAL HEALTH SURVEY
Keywords:
psychotic experiences, lifetime prevalence, regional variation, decomposition analysis, ThailandAbstract
Objectives: To investigate whether lifetime psychotic experiences differ in their regional distribution patterns across Thailand and to explore geographic heterogeneity in the lifetime occurrence of these symptoms using Thailand's diverse regions as a natural experimental setting.
Material and Methods: A cross-sectional analysis was conducted of 4,160 adults participating in the 2023 Thai National Mental Health Survey across six regions (Bangkok, Central, North, Northeast, South, and Southern Border). Lifetime psychotic experiences were assessed using the World Health Organization Composite International Diagnostic Interview version 3.0 (WHO-CIDI 3.0) Psychosis Screener with standard exclusions. Adjusted prevalences and prevalence ratios were estimated using generalized linear models. Fairlie's non-linear decomposition, with primary sampling unit–level bootstrap (1,000 replicates), partitioned regional differences into compositional and contextual components. Region-by–risk factor interactions were tested in pooled models with an alpha of 0.10.
Results: The overall prevalence of lifetime psychotic experiences was 3.0 % (95 %CI: 2.3–3.9%). Lifetime hallucination prevalence varied substantially by region, ranging from 1.0% to 4.3% after adjustment, about a fourfold difference. Delusions showed minimal regional variation (0.2–1.1%; p = 0.234), with a mean of 4.3%. After adjustment, the South had a significantly lower prevalence of hallucinations (prevalence ratio, 0.34; 95% CI, 0.15–0.78) compared with Bangkok. Fairlie decomposition indicated that demographic composition explained 57% of the Northeast–Bangkok difference but only 30% of the South–Bangkok protective effect. Significant region–by–risk factor interactions were observed; for example, unemployment had a stronger association in the Northeast compared with Bangkok (prevalence ratio, 1.71; 95% CI: 1.08–2.71; p-interaction = 0.042).
Conclusion: Lifetime hallucinations showed marked regional heterogeneity, only partially explained by demographic composition. Between 43 % and 70 % of regional differences were unexplained by individual characteristics, indicating substantial place-based effects on the accumulation of lifetime psychotic experiences.
References
Van Os J, Linscott RJ, Myin-Germeys I, Delespaul P, Krabbendam L. A systematic review and meta-analysis of the psychosis continuum: Evidence for a psychosis proneness-persistence-impairment model of psychotic disorder. Psychol Med 2009; 39(2): 179-95.
McGrath JJ, Saha S, Al-Hamzawi A, et al. The bidirectional associations between psychotic experiences and DSM-IV mental disorders. Am J Psychiatry 2016; 173(10): 997-1006.
Linscott RJ, van Os J. An updated and conservative systematic review and meta-analysis of epidemiological evidence on psychotic experiences in children and adults: On the pathway from proneness to persistence to dimensional expression across mental disorders. Psychol Med 2013; 43(6): 1133-49.
McGrath JJ, Saha S, Al-Hamzawi A, et al. Psychotic experiences in the general population: A cross-national analysis based on 31,261 respondents from 18 countries. JAMA Psychiatry 2015; 72(7): 697-705.
Kirkbride JB, Hameed Y, Ankireddypalli G, et al. The epidemiology of first-episode psychosis in early intervention in psychosis services: Findings from the Social Epidemiology of Psychoses in East Anglia [SEPEA] study. Am J Psychiatry 2017; 174(2): 143-53.
Rigg J, Salamanca A. Connecting lives, living, and location: Mobility and spatial signatures in Northeast Thailand, 1982–2009. Critical Asian Studies 2011; 43(4): 551-75.
Supanya S. Prevalence and distribution of psychotic experiences in the Thai population: findings from the 2023 national mental health survey. J Mental Health Thailand 2025; 33(2): 101-13.
Supanya S. Trends in Psychotic Experiences in Bangkok: Informing the Planned Early Intervention Service at Somdet Chaopraya Institute of Psychiatry. J Psychiatric Association Thailand 2025; 70(2): 206-14.
Jann B. The Blinder-Oaxaca decomposition for linear regression models. Stata J 2008; 8(4): 453-79.
Selten JP, van der Ven E, Rutten BP, Cantor-Graae E. The social defeat hypothesis of schizophrenia: An update. Schizophr Bull 2013; 39(6): 1180-6.
Heeringa SG, Wells JE, Hubbard F, et al. Sample designs and sampling procedures. In: Kessler RC, Üstün TB, eds. The WHO World Mental Health Surveys: Global perspectives on the epidemiology of mental disorders. Cambridge University Press; 2008: 14-32.
StataCorp. Stata Statistical Software: Release 14. College Station, TX: StataCorp LP; 2015.
Kessler RC, Üstün TB. The World Mental Health (WMH) Survey Initiative Version of the World Health Organization (WHO) Composite International Diagnostic Interview (CIDI). Int J Methods Psychiatr Res 2004; 13(2): 93-121.
Kittirattanapaiboon P, Tantirangsee N, Chutha W, Tanaree A, Kwansanit P, Assanangkornchai S, Supanya S. Thai National Mental Health Survey 2013: Methodology and rationale. J Mental Health Thailand 2017; 25(1): 1-14.
Barros AJD, Hirakata VN. Alternatives for logistic regression in cross-sectional studies: an empirical comparison of models that directly estimate the prevalence ratio. BMC Med Res Methodol 2003; 3:21.
Zou G. A modified Poisson regression approach to prospective studies with binary data. Am J Epidemiol 2004; 159(7): 702-6.
Loch AA, Wang YP, Rossler W, Tofoli LF, Silveira CM, Andrade LH. The psychosis continuum in the general population: findings from the São Paulo Epidemiologic Catchment Area Study. Eur Arch Psychiatry Clin Neurosci 2011; 261(7): 519-27.
Jongsma HE, Gayer-Anderson C, Lasalvia A, et al. Treated incidence of psychotic disorders in the multinational EU-GEI study. JAMA Psychiatry 2018; 75(1): 36-46.
Tortelli A, Errazuriz A, Croudace T, et al. Schizophrenia and other psychotic disorders in Caribbean-born migrants and their descendants in England: systematic review and meta-analysis of incidence rates, 1950-2013. Soc Psychiatry Psychiatr Epidemiol 2015; 50(7): 1039-55.
Collip D, Myin-Germeys I, Van Os J. Does the concept of "sensitization" provide a plausible mechanism for the putative link between the environment and schizophrenia?. Schizophr Bull 2008; 34(2): 220-5.
Zhang J, Yu KF. What's the relative risk? A method of correcting the odds ratio in cohort studies of common outcomes. JAMA 1998; 280(19): 1690-1.
Fairlie RW. An extension of the Blinder-Oaxaca decomposition technique to logit and probit models. J Econ Soc Meas 2005; 30(4): 305-6.
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